On Sun, 23 Jun 2019 12:05:52 +1000, Xeno
wrote:

On 23/6/19 1:57 am, Rod Speed wrote:


"trader_4" wrote in message
...
On Saturday, June 22, 2019 at 6:00:41 AM UTC-4, Brian Gaff wrote:
Yes indeed, the nominal output of an alternator can be as high as 15
volts,
but even a fully charged car battery is only 13.8v as far as I know and
these days, I'm sure the direction of current flow and voltages are
monitored very well by the computers. In the old days it was a bit of a
black art just relying on the ability of the alternator or dynamo in
the old
bangers.

Nonsense.* Cars used voltage regulators for better part of a century and
they are simple electronics which is well understood.* And, AFAIK,
that is STILL how it's done, all the FUD here notwithstanding.* Some
cars may have something more elaborate, but it's obviously not required
to keep the battery correctly charged, which was the OPs question about
charging.

No it wasn’t, he asked about changing to a trickle charge when the battery
is fully charged.

Battery chargers do it automatically - if they are decent.
Alternators too do it automatically.
SOME chargers - and some vehicles that use the computer to control
charge, use a "3 step" algorythm which uses constant current to "bulk
charge" the battery to a certain level, then switch to constant
voltage untill output current drops below a certain point where it
switches to "float charge". Not COMMON on cars, but getting pretty
common on higher end chargers to prevent overcharging and gassing of
the battery when left on charge. The old service station type chargers
had a simple timer to accomplish this - and some of the later ones had
a combination - when charging voltage exceded a certain point it would
charge for anothe X number of minutes before shutting down.

Automotive charging systems that actually sense current are
EXCEDEINGLY RARE.

On Mon, 24 Jun 2019 00:26:27 +0100, Clare Snyder wrote:

On Sat, 22 Jun 2019 16:03:07 -0500, Mark Lloyd
wrote:

On 6/21/19 5:55 PM, Commander Kinsey wrote:

[snip]

I guess charging a car battery with a charger plugged into the house
won't work if you have a load in the car like lights (or in my case a
faulty alarm). The charger will think the battery is still drawing a
fair current and isn't full, when in fact it's the load eating it up.

I've tried it with an automatic charger. If the load is enough that the
battery won't change within a certain time, the charger stops and
indicates an error.

[snip]
That's just with "smart chargers" I've had 3 and they both ended up
"brain dead" and would report a shorted cell on a perfectly good
battery.

You had 3 and they BOTH ended up dead?

On Sun, 23 Jun 2019 15:22:25 +0100, trader_4 wrote:

On Saturday, June 22, 2019 at 7:25:04 PM UTC-4, Commander Kinsey wrote:
On Sat, 22 Jun 2019 16:29:26 +0100, trader_4 wrote:

On Saturday, June 22, 2019 at 6:41:22 AM UTC-4, Xeno wrote:
On 22/6/19 7:58 pm, Rod Speed wrote:


"Xeno" wrote in message
...
On 22/6/19 9:57 am, Rod Speed wrote:


"Commander Kinsey" wrote in message
news On Fri, 21 Jun 2019 23:57:52 +0100, Rod Speed
wrote:



"Commander Kinsey" wrote in message
news On Fri, 21 Jun 2019 22:57:44 +0100, Max Demian

wrote:

On 21/06/2019 21:19, Commander Kinsey wrote:
How does a lead acid battery charger (or car alternator) know
when to
switch to trickle charge? I can understand it noticing a drop in
charging current if the battery is on its own, but what if a random
changing load is connected, as there is in a running car?

The voltage perhaps.

Why would the voltage change?

That's the way batterys work, the battery voltage does change as its
charged.

That's determined by the alternator or charger.

Nope.

Yip.

Nope.

I can put any voltage I like across a battery's terminals.

Nope.

The battery then chooses how much current is drawn.

And that current changes depending on the how charged the battery is.

Let's say the charger/alternator gives out 14.4V initially, to
charge the
battery quickly. It'll just sit at 14.4V forever, providing the
charger
can give out enough current to charge the slightly flat battery
and power
any connected loads.

Its more complicated than that with the current going to the
battery and the
battery is charged.

If the battery had no loads connected, it would take a lot less
current
when it became full, but the voltage would stay the same.

No it doesn't even with a very crude battery charger.

For example, I'm currently keeping my car's battery topped up with a
bench supply overnight. It's set to 13.8V, with a current limiter
only to prevent overloading the supply.

It actually specify the current being supplied.

The voltage stays at 13.8V all the time, sometimes 100mA is drawn,
sometimes up to 4A. The only way I or the supply can tell the
battery is full, is by the current dropping to 100mA. But it's
actually always full, as when 4A is drawn, that's going to a load.

What load ? There no load with a battery being charged with a bench
supply.

Correction

Nope.

the *battery* is the *load*.

Not when the battery is fully charges and is being charged
with a bench supply that is delivering 4A to the battery.

Take the case of an alternator charging a battery at ~4 amps. The
battery is the load and it also provides, as part of that function, the
reference *voltage* that the alternator *must have* in order to control
the output.

+1
You are 100% correct.

You do realize who you are dealing with here, right? Here is some of
the other BS he posted and then just continued to lie about, refuse
to acknowledge it was all wrong:

How can one dope be wrong on so many things?



The 737 MCAS doesn't rely on just one AOA sensor (It does)

The FAA would never approve that design (They did)

[snip]

You've already posted all that ****e. Repeating yourself is a sign of illness.

No, arguing with the Aussie troll who has a track record of BS and lies
is the illness. Maybe you don't care about anyone's credibility and
will debate nuclear physics with the village idiot who lies about most
things. Do so at your own risk.

He may be an argumentative prick, but he does know a fair bit about a lot of things.

And you're the one that keeps going on and on about things he's said. You're trolling him, I'm arguing and discussing with him.

On Sun, 23 Jun 2019 15:22:13 +0100, trader_4 wrote:

On Saturday, June 22, 2019 at 7:30:59 PM UTC-4, Commander Kinsey wrote:
On Sat, 22 Jun 2019 16:16:30 +0100, trader_4 wrote:

On Friday, June 21, 2019 at 7:33:38 PM UTC-4, Commander Kinsey wrote:
On Fri, 21 Jun 2019 23:57:52 +0100, Rod Speed wrote:



"Commander Kinsey" wrote in message
news On Fri, 21 Jun 2019 22:57:44 +0100, Max Demian
wrote:

On 21/06/2019 21:19, Commander Kinsey wrote:
How does a lead acid battery charger (or car alternator) know when to
switch to trickle charge? I can understand it noticing a drop in
charging current if the battery is on its own, but what if a random
changing load is connected, as there is in a running car?

The voltage perhaps.

Why would the voltage change?

That's the way batterys work, the battery voltage does change as its
charged.

That's determined by the alternator or charger.

Nope.

Yip. I can put any voltage I like across a battery's terminals. The battery then chooses how much current is drawn.

Correct, within reason and the physical limits of the battery. A battery
looks like an ideal voltage source connected in series with a low value
resistor.





Let's say the charger/alternator gives out 14.4V initially, to charge the
battery quickly. It'll just sit at 14.4V forever, providing the charger
can give out enough current to charge the slightly flat battery and power
any connected loads.

Its more complicated than that with the current going to the battery and the
battery is charged.

If the battery had no loads connected, it would take a lot less current
when it became full, but the voltage would stay the same.

No it doesn't even with a very crude battery charger.

For example, I'm currently keeping my car's battery topped up with a bench supply overnight. It's set to 13.8V, with a current limiter only to prevent overloading the supply. The voltage stays at 13.8V all the time, sometimes 100mA is drawn, sometimes up to 4A. The only way I or the supply can tell the battery is full, is by the current dropping to 100mA. But it's actually always full, as when 4A is drawn, that's going to a load.

If the charger monitored the current it was providing, how does it know if
the battery is still charging at 10 amps, or if the battery is full and
there's a 10 amp load?

By checking the current actually being delivered to the battery.

I guess that may be true, if the car's computer has two ammeters and subtracts one from the other. But AFAIK, the alternator regulator only works by it's own current sensor. And that current could be going into the battery, or past it to the loads.

The voltage regulator actually senses VOLTAGE, which is why it;s called
a voltage regulator.

No it doesn't. It keeps the voltage at the correct level for charging, which is 14.4V for fast charge and 13.8V for trickle charge. It senses a drop in current to tell when the battery is full.

No it doesn't what? Of course the voltage regulator SENSES VOLTAGE because
otherwise it obviously can't regulate it.

It senses voltage so it can keep it steady. Voltage does not change when the battery gets full, the current draw changes.

It doesn't target CURRENT.
And this is why you keep asking about how the VR knows how much current
is going to the battery vs how much is going to the car. It doesn't.
It doesn't care. It targets VOLTAGE and that's why it's called a VOLTAGE
REGULATOR, not a current regulator. Good grief, this is explained all over
the internet, not hard to find.

How can the battery change the voltage when it's kept steady by the regulator? Find a graph of a battery being charged. Once it draws less than the maximum current the charger can provide, it stays at precisely the same voltage for the rest of the charge, and the current gradually drops. The charger senses this current drop and changes the voltage to different levels to enter the three charging phases.

On Sun, 23 Jun 2019 14:53:00 +0100, trader_4 wrote:

On Saturday, June 22, 2019 at 5:58:02 PM UTC-4, Commander Kinsey wrote:
On Sat, 22 Jun 2019 17:03:08 +0100, TMS320 wrote:

On 21/06/2019 21:19, Commander Kinsey wrote:
How does a lead acid battery charger (or car alternator) know when to
switch to trickle charge?

It doesn't.

Mine does, if I start my car when the battery is say 80% full, the voltage will be 14.4V. After a while, something causes that voltage to drop to 13.8, because something knows the battery is full and should no longer be charged at a high rate.


Go find a description of the voltage regulator/alternator and/or a
schematic for that car.

No idea where to find that.

Give us the references. If something is telling
the VR/alternator what voltage to target, then there must be an additional
wire or connection of some kind.

Agreed. And it could well have a sensor in the fusebox etc.

I have not seen that. The other possibilities
are that the VR itself lowers the target voltage, based on? Makes no sense
and I've never seen it mentioned anywhere. I just googled for VR and looked
at half a dozen references, all just say the VR targets a specific voltage
period. The other possibility is that when you read the voltage later,
some other load is present that is lowering the system voltage that you see.

No, all I did was to start the car when the battery was almost full. The battery terminal voltage was immediately 14.4V. 20 minutes later it dropped to 13.8V. I added no loads. I think it actually dropped gradually if that means anything. I actually did that test because someone in one of these groups (although some troll has deleted half the groups, so I've added them back in AGAIN) told me that a car alternator changes voltage, this was in a post 6 months ago.

I can understand it noticing a drop in
charging current if the battery is on its own, but what if a random
changing load is connected, as there is in a running car?

Ohm's law.

Explain how an alternator or charger can use ohm's law to distinguish between:
1) A car battery which is full, with a load of 10 amps connected to it, like two headlights.
2) A car battery with no load, which is not full yet and draws 10 amps for the charge.

Rod claims that they have an extra sensing wire at the battery terminal
and use the voltage there versus the voltage at the other end of the
cable, to determine the current. I seriously doubt that, for obvious
reasons involving the very large gauge cable and current of interest.

It could only be mV, but easy enough to sense with modern electronics. Or how about an amp clamp?

And he can't produce a damn thing from anywhere that says that's what
they do, except his own worthless statements. If it's done that way
anywhere, it's not done on the cars I've seen here, that have just one
battery cable on the positive terminal.

Every UK car has 2 or 3 cables on the battery positive. America is infamous for being behind the times. We all know your cars can't go round corners, and get way less HP for the same engine size.

Why doesn't someone show us
an example, a description of one of these alleged fancy voltage regulators
that are computer controlled?

On Sunday, June 23, 2019 at 3:07:53 PM UTC-4, Commander Kinsey wrote:
On Sun, 23 Jun 2019 14:39:09 +0100, trader_4 wrote:

On Saturday, June 22, 2019 at 5:22:54 PM UTC-4, Commander Kinsey wrote:
On Sat, 22 Jun 2019 16:45:08 +0100, Rod Speed wrote:



"trader_4" wrote in message
...
On Friday, June 21, 2019 at 6:48:31 PM UTC-4, wrote:
On Fri, 21 Jun 2019 23:15:21 +0100, "Commander Kinsey"
wrote:

On Fri, 21 Jun 2019 22:57:44 +0100, Max Demian
wrote:

On 21/06/2019 21:19, Commander Kinsey wrote:
How does a lead acid battery charger (or car alternator) know when to
switch to trickle charge? I can understand it noticing a drop in
charging current if the battery is on its own, but what if a random
changing load is connected, as there is in a running car?

The voltage perhaps.

Why would the voltage change? That's determined by the alternator or
charger. Let's say the charger/alternator gives out 14.4V initially, to
charge the battery quickly. It'll just sit at 14.4V forever, providing
the charger can give out enough current to charge the slightly flat
battery and power any connected loads. If the battery had no loads
connected, it would take a lot less current when it became full, but the
voltage would stay the same. If the charger monitored the current it
was providing, how does it know if the battery is still charging at 10
amps, or if the battery is full and there's a 10 amp load?

Not really true with anything but the most primative regulator like
you might see on an old outboard. Voltage is regulated somewhere
between 13.x and 14.x, not just reflecting what the alternator can do
against the load.
Rod is right, they look at current from the alternator

Every car I've seen, the the alternator, the battery
and the rest of the car are tied to one point

But there is normally more than the one wire
at the the positive terminal of the battery.

and there is no monitor for what current
is going to the battery vs to the car load.

Wrong when there is normally more than the one
wire at the the positive terminal of the battery.

And Rod is talking computers,

Because thats what his car has.

so how did cars work prior to the 80s?

The regulator uses the voltage it sees which varys
with the load and the charge of the battery.

That was my original question - on an old car, there is no way for the regulator to tell the difference between the battery still charging at 10 amps and the headlamps being switched on.

Probably on most or all new cars too. Why change what works?





And so far I haven't seen any evidence presented here that shows modern
ones can tell the difference and care about it either. The ones I've
seen, still have a voltage regulator in the alternator that functions
like it has for most of the last century. Rod claims to know so much,
including that they use the resistance of the battery cable to measure
current, but he can't produce anything other than his own flapping BS
gums and he's likely just doing the usual, making it up on the fly
and lying.

What he says sounds very easy to implement, and it would make sense to allow the battery to be put on fast charge after starting it, then go back to trickle later. And my own car certainly does change the voltage after a while. 14.4 then 13.8.

I disagree, what he says makes no sense for obvious reasons that another
poster described. And AFAIK, the VR just targets voltage, that Rod is
bloviating his usual BS doesn't change that.
But heh, if you or Rod have a reference that describes this
"new" system, that uses the resistance of the battery cable to measure
current and then the computer controls the VR, let's see it. Otherwise,
I say your question is answered,
the VR doesn't know or care where the current is going, it just maintains
a system voltage of ~14V.

On Sunday, June 23, 2019 at 2:54:41 PM UTC-4, Rod Speed wrote:
"trader_4" wrote in message
...
On Sunday, June 23, 2019 at 9:56:21 AM UTC-4, Dean Hoffman wrote:
On 6/23/19 8:39 AM, trader_4 wrote:

And so far I haven't seen any evidence presented here that shows modern
ones can tell the difference and care about it either. The ones I've
seen, still have a voltage regulator in the alternator that functions
like it has for most of the last century. Rod claims to know so much,
including that they use the resistance of the battery cable to measure
current, but he can't produce anything other than his own flapping BS
gums and he's likely just doing the usual, making it up on the fly
and lying.

One problem with what he's suggesting is the connection from the
cable to
the battery itself if I understand what he's saying. I've seen so many
bad connections
over the years. Wiggling that connection or putting a sheet metal screw
in it changes
the resistance dramatically.
A few feet of wire in an engine compartment won't have much
resistance to measure.
It would take a very sensitive tester to measure that little bit. 14
awg copper wire has about 2.5 ohms resistance per 1000 feet. #2 awg
wire has about 0.16 ohms per 1000 feet.

Bingo! We have a winner!

Nope.

Exactly what I was thinking when I said it seems unlikely
that they would use the resistance of a heavy, 2g battery
cable to try to measure current flow to the battery.

What is measured is the voltage drop across that cable.
Thats what gives you the current thru it, stupid.

You have 3 feet of wire, to determine whether the battery
is getting 100ma or 10 amps, good luck with that,

Trivially easy to do by measuring the voltage drop across that cable.

especially in a potentially noisy environment, with
system loads turning on and off rapidly, etc.

That doesnt happen with the car running.

Figure out how small those voltages would be.

Trivially easy to measure and the arent that small
with the total current the entire electrical system
takes and with the current thats charging the battery.

And note I'm not saying that some cars, somewhere don't have
some more advanced system, it's certainly possible, maybe to slightly
reduce wasted energy, at the expense of increased complexity.

Nothing to do with wasted energy.

Show us any reference that says this is what is actually done.
Waiting...... Nuff said.

On Sunday, June 23, 2019 at 2:35:56 PM UTC-4, Rod Speed wrote:
"Dean Hoffman" wrote in message
...
On 6/23/19 8:39 AM, trader_4 wrote:

And so far I haven't seen any evidence presented here that shows modern
ones can tell the difference and care about it either. The ones I've
seen, still have a voltage regulator in the alternator that functions
like it has for most of the last century. Rod claims to know so much,
including that they use the resistance of the battery cable to measure
current, but he can't produce anything other than his own flapping BS
gums and he's likely just doing the usual, making it up on the fly
and lying.

One problem with what he's suggesting is the connection from the cable to
the battery itself

Nope.

if I understand what he's saying.

You clearly dont.

I've seen so many bad connections over the years. Wiggling that
connection or putting a sheet metal screw in it changes the resistance
dramatically.

Yes, but that has no effect on the RESISTANCE
of the substantial wire between the positive
terminal connector and the other end of that wire.

A few feet of wire in an engine compartment won't have much resistance to
measure.

What is measured is the voltage drop across that wire.
Thats acting like an ammeter shunt.

It would take a very sensitive tester to measure that little bit.

Trivial to measure the VOLTAGE DROP across that wire.

14 awg copper wire has about 2.5 ohms resistance per 1000 feet. #2 awg
wire has about 0.16 ohms per 1000 feet.


Show us any reference that says this is what is actually done.
Waiting...... Nuff said.

On 24/6/19 9:11 am, Clare Snyder wrote:
On Fri, 21 Jun 2019 13:48:56 -0700, % wrote:

On 2019-06-21 1:19 p.m., Commander Kinsey wrote:
How does a lead acid battery charger (or car alternator) know when to
switch to trickle charge?Â* I can understand it noticing a drop in
charging current if the battery is on its own, but what if a random
changing load is connected, as there is in a running car?

the catalytic converter tells it
I can tell you how an alternator does it, chargerscan do it
differently. AN alternator doesn't "switch to trickle charge". AN
alternator limits the output voltage. A battery will only accept a
certain amount of charge at any voltage. At 14.6 volts it basically
stops taking a charge. The regulator is set to limit the voltage to a
specified voltage - 13.8 or 14.2, or something similar. An alternator

The Zener will limit the voltage to something like 14.2V or thereabouts,
with temperature compensation.
The ideal rate for charging a battery lies in the range 13.8-14.1V. This
range provides the maximum battery service life and limits the heat
generated within the battery. The disadvantage is that the charge time
is much longer and there exists a risk of sulphation.
Between 14.4 and 14.7V there is less risk of sulphation but a higher
risk of grid corrosion on the positive plates and gassing. This will
require topping up of the water content of the electrolyte and can cause
severe overcharging if ambient temperatures are high.

is intrinsically current limitted so will not provide more than the
rated current, If the battery open circuit voltage is below 12 volts
it will tale pretty close to whatever the alternator can put out, as
the open circuit voltage increases, the amount of charge it will

And that voltage increase is in step with battery internal resistance.

accept decreases, untill at 14.6 volts or whatever is designed as full
charge, it will no longer accept ANY charge. As the load changes, the
alternator provides more or less current as required to maintain the
fully charged voltage.

Clear as mud???

It will only be muddy to those without a clue. ;-)

I wouldn't have thought it a particularly difficult set of concepts to
understand, especially in this day and age when there are heaps of texts
on the topic describing the operation of *all aspects* of a vehicle's
electrical system and freely available on the internet. All that is
required is an understanding of the fundamentals of electricity and,
these days, electronics.


--

Xeno


Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)

On 24/6/19 9:38 am, Clare Snyder wrote:
On Sun, 23 Jun 2019 12:04:19 +1000, Xeno
wrote:

On 23/6/19 1:45 am, Rod Speed wrote:


"trader_4" wrote in message
...
On Friday, June 21, 2019 at 6:48:31 PM UTC-4, wrote:
On Fri, 21 Jun 2019 23:15:21 +0100, "Commander Kinsey"
wrote:

On Fri, 21 Jun 2019 22:57:44 +0100, Max Demian
wrote:

On 21/06/2019 21:19, Commander Kinsey wrote:
How does a lead acid battery charger (or car alternator) know
when to
switch to trickle charge?Â* I can understand it noticing a drop in
charging current if the battery is on its own, but what if a random
changing load is connected, as there is in a running car?

The voltage perhaps.

Why would the voltage change?Â* That's determined by the alternator
or charger.Â* Let's say the charger/alternator gives out 14.4V
initially, to charge the battery quickly.Â* It'll just sit at 14.4V
forever, providing the charger can give out enough current to charge
the slightly flat battery and power any connected loads.Â* If the
battery had no loads connected, it would take a lot less current
when it became full, but the voltage would stay the same.Â* If the
charger monitored the current it was providing, how does it know if
the battery is still charging at 10 amps, or if the battery is full
and there's a 10 amp load?

Not really true with anything but the most primative regulator like
you might see on an old outboard. Voltage is regulated somewhere
between 13.x and 14.x, not just reflecting what the alternator can do
against the load.
Rod is right, they look at current from the alternator

Every car I've seen, the the alternator, the battery
and the rest of the car are tied to one point

But there is normally more than the one wire
at the the positive terminal of the battery.

Parallel circuits, so what?

and there is no monitor for what current
is going to the battery vs to the car load.

Wrong when there is normally more than the one
wire at the the positive terminal of the battery.

And Rod is talking computers,

Because thats what his car has.

so how did cars work prior to the 80s?

The regulator uses the voltage it sees which varys
with the load and the charge of the battery.

They didn't have a computer didn't monitor anything
other than the voltage regulator maintained a constant
voltage of ~14v while the car was running.

Its more complicated than that with the voltage.

No it isn't.

It was that way from the early days and auto batteries charged fine.

Generators do it differently to alternators and we arent discussing
whether they charged fine or not, we are discussing what the
regulator does when the battery is fully charged so that it doesnt
boil off the water in the battery. Thats particularly important
now that most car batterys arent refillable with water anymore.

There may be some modern cars where they do monitor the current going
to the battery, maybe to save energy and increase fuel consumption,

It actually to avoid ****ing the battery by delivering
the same current to the battery when its fully charged.

but it's not necessary to keeping the battery charged.

That isnt what is being discussed either.

There is nothing they can do about the load so they don't
give a **** about the lights.Â* The regulator just watches
alternator current and cranks up the voltage to keep it up.

That's rather bizarre.Â* The alternator monitors current?Â* So, what's
the correct current that it's targeting?Â* 2 amps, 20 amps?Â* 70 amps?
The current depends on what loads are on and the alternator doesn't
know that.Â* Seems to me it keeps the system VOLTAGE at ~14V

No it doesnt. Doing that would overcharge a fully charged battery.

and that has worked for 100 years.

Wrong again, generators do it differently to alternators.

Yes, no argument there. You mean like this;
http://mgaguru.com/mgtech/books/pdf/..._Box_Tests.pdf

Voltage and current control. They were pretty much on the way out by the
time I finished my apprenticeship.

With alternators, voltage is key.

You need to get with the times. Generators went out with button up boots.
A generator generally used a "3 unit regulator" Onewas the cut-out -
which is replaced by the diodes in an alternator. The alternator
cannot drain the battery attempting to "motor" itself like a
generator. The second unit was the current regulator, because a
generator is NOT self limitting. If you full feild a generator into a
dead short it will melt itesrlf down.

Some generators used only two bobbins. One was for voltage regulation,
the other the cutout. I used to see both types in the time of my
apprenticeship but by the time I finished, they were well and truly on
the way out. One of my teaching colleagues, an *old school* mechanic,
was an absolute wizard on those 3 bobbin regulators and also early
alternator systems. I did specialised automotive electrical training
under his tutelage and, through that, I developed more efficient ways of
delivering training in auto electrical aspects. All that was a long time
ago and my recall is getting rusty.

An alternator is self limiting due to it's higher stator resistance.It
will ONLY put out a certain amount of current into a load, regardless
of the resistance of the load. This is due to both the stator
resistance and the maximum flux of the rotor - so the current
regulator (actually "limitter" as it only controls the maximum output)
is not required on an alternator either. This leaves the voltage
regulator, which controls the feild current either linearly or by
"chopping" - or pulse width modulation. The more current flowing in
the feild the higher power produced - in volt-amps. As the current
changes, the voltage changes in reverse, for the same feild strength.
Higher current = lower voltage. By sensing and controlling the voltage
the current pretty much looks after itself - as the regulator
controlls the feild strenth by varying the feild current. It controls
the feild current by controlling the voltage impressed across the
feild coil.. As the engine speeds up, it requires less feild strength
to produce the same voltage.

Indeed, quite a simple system really.

--

Xeno


Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)

On 24/6/19 9:45 am, Clare Snyder wrote:
On Sun, 23 Jun 2019 12:05:52 +1000, Xeno
wrote:

On 23/6/19 1:57 am, Rod Speed wrote:


"trader_4" wrote in message
...
On Saturday, June 22, 2019 at 6:00:41 AM UTC-4, Brian Gaff wrote:
Yes indeed, the nominal output of an alternator can be as high as 15
volts,
but even a fully charged car battery is only 13.8v as far as I know and
these days, I'm sure the direction of current flow and voltages are
monitored very well by the computers. In the old days it was a bit of a
black art just relying on the ability of the alternator or dynamo in
the old
bangers.

Nonsense.Â* Cars used voltage regulators for better part of a century and
they are simple electronics which is well understood.Â* And, AFAIK,
that is STILL how it's done, all the FUD here notwithstanding.Â* Some
cars may have something more elaborate, but it's obviously not required
to keep the battery correctly charged, which was the OPs question about
charging.

No it wasnt, he asked about changing to a trickle charge when the battery
is fully charged.

Battery chargers do it automatically - if they are decent.
Alternators too do it automatically.
SOME chargers - and some vehicles that use the computer to control
charge, use a "3 step" algorythm which uses constant current to "bulk
charge" the battery to a certain level, then switch to constant
voltage untill output current drops below a certain point where it
switches to "float charge". Not COMMON on cars, but getting pretty

A car charging system is unlikely to ever really *need* a float charge
mode since it has to deal with other electrical system loads as well as
the needs of the battery. That and the type of use the car battery gets
adds a layer of complexity to it all that I can't see is really
warranted. A battery charger, on the other hand, has to deal only with
one load, the battery.

common on higher end chargers to prevent overcharging and gassing of
the battery when left on charge. The old service station type chargers
had a simple timer to accomplish this - and some of the later ones had
a combination - when charging voltage exceded a certain point it would
charge for anothe X number of minutes before shutting down.



Automotive charging systems that actually sense current are
EXCEDEINGLY RARE.

I've never seen one.

--

Xeno


Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)

"trader_4" wrote in message
...
On Sunday, June 23, 2019 at 3:07:53 PM UTC-4, Commander Kinsey wrote:
On Sun, 23 Jun 2019 14:39:09 +0100, trader_4
wrote:

On Saturday, June 22, 2019 at 5:22:54 PM UTC-4, Commander Kinsey wrote:
On Sat, 22 Jun 2019 16:45:08 +0100, Rod Speed
wrote:



"trader_4" wrote in message
...
On Friday, June 21, 2019 at 6:48:31 PM UTC-4,
wrote:
On Fri, 21 Jun 2019 23:15:21 +0100, "Commander Kinsey"
wrote:

On Fri, 21 Jun 2019 22:57:44 +0100, Max Demian

wrote:

On 21/06/2019 21:19, Commander Kinsey wrote:
How does a lead acid battery charger (or car alternator) know
when to
switch to trickle charge? I can understand it noticing a drop
in
charging current if the battery is on its own, but what if a
random
changing load is connected, as there is in a running car?

The voltage perhaps.

Why would the voltage change? That's determined by the
alternator or
charger. Let's say the charger/alternator gives out 14.4V
initially, to
charge the battery quickly. It'll just sit at 14.4V forever,
providing
the charger can give out enough current to charge the slightly
flat
battery and power any connected loads. If the battery had no
loads
connected, it would take a lot less current when it became full,
but the
voltage would stay the same. If the charger monitored the
current it
was providing, how does it know if the battery is still charging
at 10
amps, or if the battery is full and there's a 10 amp load?

Not really true with anything but the most primative regulator
like
you might see on an old outboard. Voltage is regulated somewhere
between 13.x and 14.x, not just reflecting what the alternator can
do
against the load.
Rod is right, they look at current from the alternator

Every car I've seen, the the alternator, the battery
and the rest of the car are tied to one point

But there is normally more than the one wire
at the the positive terminal of the battery.

and there is no monitor for what current
is going to the battery vs to the car load.

Wrong when there is normally more than the one
wire at the the positive terminal of the battery.

And Rod is talking computers,

Because thats what his car has.

so how did cars work prior to the 80s?

The regulator uses the voltage it sees which varys
with the load and the charge of the battery.

That was my original question - on an old car, there is no way for the
regulator to tell the difference between the battery still charging at
10 amps and the headlamps being switched on.

Probably on most or all new cars too. Why change what works?





And so far I haven't seen any evidence presented here that shows modern
ones can tell the difference and care about it either. The ones I've
seen, still have a voltage regulator in the alternator that functions
like it has for most of the last century. Rod claims to know so much,
including that they use the resistance of the battery cable to measure
current, but he can't produce anything other than his own flapping BS
gums and he's likely just doing the usual, making it up on the fly
and lying.

What he says sounds very easy to implement, and it would make sense to
allow the battery to be put on fast charge after starting it, then go
back to trickle later. And my own car certainly does change the voltage
after a while. 14.4 then 13.8.

I disagree, what he says makes no sense for obvious reasons that another
poster described. And AFAIK, the VR just targets voltage, that Rod is
bloviating his usual BS doesn't change that.
But heh, if you or Rod have a reference that describes this
"new" system, that uses the resistance of the battery cable to measure
current and then the computer controls the VR, let's see it. Otherwise,
I say your question is answered,
the VR doesn't know or care where the current is going, it just maintains
a system voltage of ~14V.

His car clearly doesnt, ****wit child.

"trader_4" wrote in message
...
On Sunday, June 23, 2019 at 2:54:41 PM UTC-4, Rod Speed wrote:
"trader_4" wrote in message
...
On Sunday, June 23, 2019 at 9:56:21 AM UTC-4, Dean Hoffman wrote:
On 6/23/19 8:39 AM, trader_4 wrote:

And so far I haven't seen any evidence presented here that shows
modern
ones can tell the difference and care about it either. The ones
I've
seen, still have a voltage regulator in the alternator that
functions
like it has for most of the last century. Rod claims to know so
much,
including that they use the resistance of the battery cable to
measure
current, but he can't produce anything other than his own flapping
BS
gums and he's likely just doing the usual, making it up on the fly
and lying.

One problem with what he's suggesting is the connection from
the
cable to
the battery itself if I understand what he's saying. I've seen so
many
bad connections
over the years. Wiggling that connection or putting a sheet metal
screw
in it changes
the resistance dramatically.
A few feet of wire in an engine compartment won't have much
resistance to measure.
It would take a very sensitive tester to measure that little bit. 14
awg copper wire has about 2.5 ohms resistance per 1000 feet. #2 awg
wire has about 0.16 ohms per 1000 feet.

Bingo! We have a winner!

Nope.

Exactly what I was thinking when I said it seems unlikely
that they would use the resistance of a heavy, 2g battery
cable to try to measure current flow to the battery.

What is measured is the voltage drop across that cable.
Thats what gives you the current thru it, stupid.

You have 3 feet of wire, to determine whether the battery
is getting 100ma or 10 amps, good luck with that,

Trivially easy to do by measuring the voltage drop across that cable.

especially in a potentially noisy environment, with
system loads turning on and off rapidly, etc.

That doesnt happen with the car running.

Figure out how small those voltages would be.

Trivially easy to measure and the arent that small
with the total current the entire electrical system
takes and with the current thats charging the battery.

And note I'm not saying that some cars, somewhere don't have
some more advanced system, it's certainly possible, maybe to slightly
reduce wasted energy, at the expense of increased complexity.

Nothing to do with wasted energy.

Show us any reference that says this is what is actually done.

Dont need one, he car clearly doesnt keep the voltage constant, ****wit
child.

"Xeno" wrote in message
...
On 24/6/19 9:45 am, Clare Snyder wrote:
On Sun, 23 Jun 2019 12:05:52 +1000, Xeno
wrote:

On 23/6/19 1:57 am, Rod Speed wrote:


"trader_4" wrote in message
...
On Saturday, June 22, 2019 at 6:00:41 AM UTC-4, Brian Gaff wrote:
Yes indeed, the nominal output of an alternator can be as high as 15
volts,
but even a fully charged car battery is only 13.8v as far as I know
and
these days, I'm sure the direction of current flow and voltages are
monitored very well by the computers. In the old days it was a bit of
a
black art just relying on the ability of the alternator or dynamo in
the old
bangers.

Nonsense. Cars used voltage regulators for better part of a century
and
they are simple electronics which is well understood. And, AFAIK,
that is STILL how it's done, all the FUD here notwithstanding. Some
cars may have something more elaborate, but it's obviously not
required
to keep the battery correctly charged, which was the OPs question
about
charging.

No it wasnt, he asked about changing to a trickle charge when the
battery
is fully charged.

Battery chargers do it automatically - if they are decent.
Alternators too do it automatically.
SOME chargers - and some vehicles that use the computer to control
charge, use a "3 step" algorythm which uses constant current to "bulk
charge" the battery to a certain level, then switch to constant
voltage untill output current drops below a certain point where it
switches to "float charge". Not COMMON on cars, but getting pretty

A car charging system is unlikely to ever really *need* a float charge
mode since it has to deal with other electrical system loads as well as
the needs of the battery. That and the type of use the car battery gets
adds a layer of complexity to it all that I can't see is really warranted.
A battery charger, on the other hand, has to deal only with one load, the
battery.

common on higher end chargers to prevent overcharging and gassing of
the battery when left on charge. The old service station type chargers
had a simple timer to accomplish this - and some of the later ones had
a combination - when charging voltage exceded a certain point it would
charge for anothe X number of minutes before shutting down.



Automotive charging systems that actually sense current are
EXCEDEINGLY RARE.

I've never seen one.

You just have. His Renault clearly is reducing the voltage once
it has decided that the battery is fully charged and that can
only be by sensing the current that the battery is taking.

On 24/6/19 1:37 pm, Rod Speed wrote:


"Xeno" wrote in message
...
On 24/6/19 9:45 am, Clare Snyder wrote:
On Sun, 23 Jun 2019 12:05:52 +1000, Xeno
wrote:

snip


Â* Automotive charging systems that actually sense current are
EXCEDEINGLY RARE.

I've never seen one.

You just have. His Renault clearly is reducing the voltage once
it has decided that the battery is fully charged and that can
only be by sensing the current that the battery is taking.

It looks at the *voltage*. It operates on the *voltage* and it alters
the voltage according to the needs of the battery and the rest of the
electrical system.

--

Xeno


Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)

"Xeno" wrote in message
...
On 24/6/19 1:37 pm, Rod Speed wrote:


"Xeno" wrote in message
...
On 24/6/19 9:45 am, Clare Snyder wrote:
On Sun, 23 Jun 2019 12:05:52 +1000, Xeno
wrote:

snip


Automotive charging systems that actually sense current are
EXCEDEINGLY RARE.

I've never seen one.

You just have. His Renault clearly is reducing the voltage once
it has decided that the battery is fully charged and that can
only be by sensing the current that the battery is taking.

It looks at the *voltage*. It operates on the *voltage* and it alters the
voltage according to the needs of the battery and the rest of the
electrical system.

The voltage doesnt tell you when a lead acid battery is fully charged.

On 24/6/19 3:58 pm, Rod Speed wrote:


"Xeno" wrote in message
...
On 24/6/19 1:37 pm, Rod Speed wrote:


"Xeno" wrote in message
...
On 24/6/19 9:45 am, Clare Snyder wrote:
On Sun, 23 Jun 2019 12:05:52 +1000, Xeno
wrote:

snip


Â* Automotive charging systems that actually sense current are
EXCEDEINGLY RARE.

I've never seen one.

You just have. His Renault clearly is reducing the voltage once
it has decided that the battery is fully charged and that can
only be by sensing the current that the battery is taking.

It looks at the *voltage*. It operates on the *voltage* and it alters
the voltage according to the needs of the battery and the rest of the
electrical system.

The voltage doesnt tell you when a lead acid battery is fully charged.

The voltage is referencing the battery internal resistance. That
resistance changes (rises) as the battery charges.

The open circuit voltage of a battery is indicative of its state of charge;

Voltage | 11.7 | 12 | 12.2 | 12.4 | 12.6 or more
% Charge | 0% | 25% | 50% | 75% | 100%

No need to look at *current* to work out charge rate, the voltage
reading does the same thing.

--

Xeno


Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)

"Xeno" wrote in message
...
On 24/6/19 3:58 pm, Rod Speed wrote:


"Xeno" wrote in message
...
On 24/6/19 1:37 pm, Rod Speed wrote:


"Xeno" wrote in message
...
On 24/6/19 9:45 am, Clare Snyder wrote:
On Sun, 23 Jun 2019 12:05:52 +1000, Xeno
wrote:

snip


Automotive charging systems that actually sense current are
EXCEDEINGLY RARE.

I've never seen one.

You just have. His Renault clearly is reducing the voltage once
it has decided that the battery is fully charged and that can
only be by sensing the current that the battery is taking.

It looks at the *voltage*. It operates on the *voltage* and it alters
the voltage according to the needs of the battery and the rest of the
electrical system.

The voltage doesnt tell you when a lead acid battery is fully charged.

The voltage is referencing the battery internal resistance.

Bull**** it is when the battery is being charged by the alternator in a car.

That resistance changes (rises) as the battery charges.

Bull**** it does when the battery is being charged by the alternator in a
car.

The open circuit voltage of a battery is indicative of its state of
charge;

There is no open circuit voltage then its being charged by the alternator in
the car.

Voltage | 11.7 | 12 | 12.2 | 12.4 | 12.6 or more % Charge | 0% | 25% | 50%
| 75% | 100%

No need to look at *current* to work out charge rate, the voltage reading
does the same thing.

Pity that there is no open circuit voltage then its being charged by the
alternator in the car.

On Mon, 24 Jun 2019 13:37:19 +1000, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:


I've never seen one.

You just have.

LOL What's this with your auto-contradicting mania, senile Rodent? Isn't
that the one reason why you OBVIOUSLY have no one to talk to in real life?

--
Kerr-Mudd,John addressing senile Rot:
"Auto-contradictor Rod is back! (in the KF)"
MID:

On Mon, 24 Jun 2019 15:58:05 +1000, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:


It looks at the *voltage*. It operates on the *voltage* and it alters the
voltage according to the needs of the battery and the rest of the
electrical system.

The voltage doesn¢t tell you

Obviously it does, you ridiculous auto-contradicting, senile asshole! tsk

--
addressing nym-shifting senile Rodent:
"You on the other hand are a heavyweight bull****ter who demonstrates
your particular prowess at it every day."
MID:

On Mon, 24 Jun 2019 13:29:32 +1000, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:


Show us any reference that says this is what is actually done.

Don¢t need one

LOL So much wisdom in one self-opinionated, self-important, lonely, senile
asshole!

--
Richard addressing Rot Speed:
"**** you're thick/pathetic excuse for a troll."
MID:

On Sun, 23 Jun 2019 18:26:38 -0700 (PDT), tardo_4, another mentally
challenged, troll-feeding, senile Yankietard, blathered again:

back to trickle later. And my own car certainly does change the voltage
after a while. 14.4 then 13.8.

I disagree,

Never disagree with clinically insane idiots, troll-feeding senile idiot!
You can see in this thread what it leads to! tsk

On Mon, 24 Jun 2019 13:28:24 +1000, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:



His car clearly doesn¢t, ****wit child.

His car is as much of a nutter as he himself (just like ALL the people he
ever meets appear to be complete nutters). It's all a product of his
clinically insane sociopathic mind! You should know about that, as it's the
same with you!

--
"Anonymous" to trolling senile Rot Speed:
"You can **** off as you know less than pig **** you sad
little ignorant ****."
MID:

On Mon, 24 Jun 2019 18:18:23 +1000, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:


Bull****

That one word would make the perfect nym for you, senile bull**** artist!

--
addressing nym-shifting senile Rodent:
"You on the other hand are a heavyweight bull****ter who demonstrates
your particular prowess at it every day."
MID:

On Sunday, June 23, 2019 at 8:07:16 PM UTC-4, Commander Kinsey wrote:
On Sun, 23 Jun 2019 14:55:23 +0100, trader_4 wrote:

On Saturday, June 22, 2019 at 6:32:20 PM UTC-4, Commander Kinsey wrote:
On Sat, 22 Jun 2019 16:20:37 +0100, trader_4 wrote:

On Friday, June 21, 2019 at 7:58:11 PM UTC-4, Rod Speed wrote:
"Commander Kinsey" wrote in message
news and subtracts one from the other. But AFAIK, the alternator regulator
only works by it's own current sensor. And that current could be going
into the battery, or past it to the loads.

Not when there is more than one wire going to the
positive terminal of the battery, and there always is.

You are so ignorant, it's beyond belief. I have three vehicles here,
not one has more than the battery cable going to it.

I've owned about 15 vehicles, and they've all had two or three, I guess they design them differently in different countries.

Nor have I even
seen a car that has more than one. It certainly may exist, but to
say that it *always* has more than one wire to the battery positive
terminal is beyond stupid. Are you as sure about that as you were
about all these other things you claimed to know so much about?


How can one dope be wrong on so many things?



The 737 MCAS doesn't rely on just one AOA sensor (It does)

The FAA would never approve that design (They did)

How sad do you have to be to collect so many quotes from somebody?


What other way would you suggest to document that Rod is full of **** most
of the time?

Well sane people only moan about something daft he says once, when he says it. Collecting the quotes and repeating them over and over just makes you more of a troll than him.


No, it documents that he's a lying asshole that's wrong about many things,
adamantly asserting his ignorance and will never acknowledge when he's
wrong. But feel free to argue with the troll. He's like a pig in the
mud, he enjoys it and doesn't care that he's proven wrong.

On Sunday, June 23, 2019 at 8:06:32 PM UTC-4, Commander Kinsey wrote:
On Sun, 23 Jun 2019 15:22:13 +0100, trader_4 wrote:

On Saturday, June 22, 2019 at 7:30:59 PM UTC-4, Commander Kinsey wrote:
On Sat, 22 Jun 2019 16:16:30 +0100, trader_4 wrote:

On Friday, June 21, 2019 at 7:33:38 PM UTC-4, Commander Kinsey wrote:
On Fri, 21 Jun 2019 23:57:52 +0100, Rod Speed wrote:



"Commander Kinsey" wrote in message
news On Fri, 21 Jun 2019 22:57:44 +0100, Max Demian
wrote:

On 21/06/2019 21:19, Commander Kinsey wrote:
How does a lead acid battery charger (or car alternator) know when to
switch to trickle charge? I can understand it noticing a drop in
charging current if the battery is on its own, but what if a random
changing load is connected, as there is in a running car?

The voltage perhaps.

Why would the voltage change?

That's the way batterys work, the battery voltage does change as its
charged.

That's determined by the alternator or charger.

Nope.

Yip. I can put any voltage I like across a battery's terminals. The battery then chooses how much current is drawn.

Correct, within reason and the physical limits of the battery. A battery
looks like an ideal voltage source connected in series with a low value
resistor.





Let's say the charger/alternator gives out 14.4V initially, to charge the
battery quickly. It'll just sit at 14.4V forever, providing the charger
can give out enough current to charge the slightly flat battery and power
any connected loads.

Its more complicated than that with the current going to the battery and the
battery is charged.

If the battery had no loads connected, it would take a lot less current
when it became full, but the voltage would stay the same.

No it doesn't even with a very crude battery charger.

For example, I'm currently keeping my car's battery topped up with a bench supply overnight. It's set to 13.8V, with a current limiter only to prevent overloading the supply. The voltage stays at 13.8V all the time, sometimes 100mA is drawn, sometimes up to 4A. The only way I or the supply can tell the battery is full, is by the current dropping to 100mA. But it's actually always full, as when 4A is drawn, that's going to a load.

If the charger monitored the current it was providing, how does it know if
the battery is still charging at 10 amps, or if the battery is full and
there's a 10 amp load?

By checking the current actually being delivered to the battery.

I guess that may be true, if the car's computer has two ammeters and subtracts one from the other. But AFAIK, the alternator regulator only works by it's own current sensor. And that current could be going into the battery, or past it to the loads.

The voltage regulator actually senses VOLTAGE, which is why it;s called
a voltage regulator.

No it doesn't. It keeps the voltage at the correct level for charging, which is 14.4V for fast charge and 13.8V for trickle charge. It senses a drop in current to tell when the battery is full.

No it doesn't what? Of course the voltage regulator SENSES VOLTAGE because
otherwise it obviously can't regulate it.

It senses voltage so it can keep it steady.

No **** sherlock.



Voltage does not change when the battery gets full,

Yet you were the one telling us that it does.



the current draw changes.

It doesn't target CURRENT.
And this is why you keep asking about how the VR knows how much current
is going to the battery vs how much is going to the car. It doesn't.
It doesn't care. It targets VOLTAGE and that's why it's called a VOLTAGE
REGULATOR, not a current regulator. Good grief, this is explained all over
the internet, not hard to find.

How can the battery change the voltage when it's kept steady by the regulator?

Who said the battery changes any voltage?



Find a graph of a battery being charged. Once it draws less than the maximum current the charger can provide, it stays at precisely the same voltage for the rest of the charge, and the current gradually drops. The charger senses this current drop and changes the voltage to different levels to enter the three charging phases.

Maybe a smart charger does, the typical auto charging system, which is what
you were asking about, from everything I've seen does not. And Clare a
retired auto mechanic just told you the same thing.

On Sunday, June 23, 2019 at 8:03:57 PM UTC-4, Commander Kinsey wrote:
On Sun, 23 Jun 2019 15:22:25 +0100, trader_4 wrote:

On Saturday, June 22, 2019 at 7:25:04 PM UTC-4, Commander Kinsey wrote:
On Sat, 22 Jun 2019 16:29:26 +0100, trader_4 wrote:

On Saturday, June 22, 2019 at 6:41:22 AM UTC-4, Xeno wrote:
On 22/6/19 7:58 pm, Rod Speed wrote:


"Xeno" wrote in message
...
On 22/6/19 9:57 am, Rod Speed wrote:


"Commander Kinsey" wrote in message
news On Fri, 21 Jun 2019 23:57:52 +0100, Rod Speed
wrote:



"Commander Kinsey" wrote in message
news On Fri, 21 Jun 2019 22:57:44 +0100, Max Demian

wrote:

On 21/06/2019 21:19, Commander Kinsey wrote:
How does a lead acid battery charger (or car alternator) know
when to
switch to trickle charge? I can understand it noticing a drop in
charging current if the battery is on its own, but what if a random
changing load is connected, as there is in a running car?

The voltage perhaps.

Why would the voltage change?

That's the way batterys work, the battery voltage does change as its
charged.

That's determined by the alternator or charger.

Nope.

Yip.

Nope.

I can put any voltage I like across a battery's terminals.

Nope.

The battery then chooses how much current is drawn.

And that current changes depending on the how charged the battery is.

Let's say the charger/alternator gives out 14.4V initially, to
charge the
battery quickly. It'll just sit at 14.4V forever, providing the
charger
can give out enough current to charge the slightly flat battery
and power
any connected loads.

Its more complicated than that with the current going to the
battery and the
battery is charged.

If the battery had no loads connected, it would take a lot less
current
when it became full, but the voltage would stay the same.

No it doesn't even with a very crude battery charger.

For example, I'm currently keeping my car's battery topped up with a
bench supply overnight. It's set to 13.8V, with a current limiter
only to prevent overloading the supply.

It actually specify the current being supplied.

The voltage stays at 13.8V all the time, sometimes 100mA is drawn,
sometimes up to 4A. The only way I or the supply can tell the
battery is full, is by the current dropping to 100mA. But it's
actually always full, as when 4A is drawn, that's going to a load.

What load ? There no load with a battery being charged with a bench
supply.

Correction

Nope.

the *battery* is the *load*.

Not when the battery is fully charges and is being charged
with a bench supply that is delivering 4A to the battery.

Take the case of an alternator charging a battery at ~4 amps. The
battery is the load and it also provides, as part of that function, the
reference *voltage* that the alternator *must have* in order to control
the output.

+1
You are 100% correct.

You do realize who you are dealing with here, right? Here is some of
the other BS he posted and then just continued to lie about, refuse
to acknowledge it was all wrong:

How can one dope be wrong on so many things?



The 737 MCAS doesn't rely on just one AOA sensor (It does)

The FAA would never approve that design (They did)

[snip]

You've already posted all that ****e. Repeating yourself is a sign of illness.

No, arguing with the Aussie troll who has a track record of BS and lies
is the illness. Maybe you don't care about anyone's credibility and
will debate nuclear physics with the village idiot who lies about most
things. Do so at your own risk.

He may be an argumentative prick, but he does know a fair bit about a lot of things.

And you're the one that keeps going on and on about things he's said. You're trolling him, I'm arguing and discussing with him.

Feel free to get a room with the asshole. He's the troll, not me. Arguing
is exactly what the troll wants. There is nothing to argue about. Rod
made some specific claims, I asked for any references to back it up, he
has come up with NOTHING. Capiche?

On Sunday, June 23, 2019 at 7:11:16 PM UTC-4, Clare Snyder wrote:
On Fri, 21 Jun 2019 13:48:56 -0700, % wrote:

On 2019-06-21 1:19 p.m., Commander Kinsey wrote:
How does a lead acid battery charger (or car alternator) know when to
switch to trickle charge?Â* I can understand it noticing a drop in
charging current if the battery is on its own, but what if a random
changing load is connected, as there is in a running car?

the catalytic converter tells it
I can tell you how an alternator does it, chargerscan do it
differently. AN alternator doesn't "switch to trickle charge". AN
alternator limits the output voltage. A battery will only accept a
certain amount of charge at any voltage. At 14.6 volts it basically
stops taking a charge. The regulator is set to limit the voltage to a
specified voltage - 13.8 or 14.2, or something similar. An alternator
is intrinsically current limitted so will not provide more than the
rated current, If the battery open circuit voltage is below 12 volts
it will tale pretty close to whatever the alternator can put out, as
the open circuit voltage increases, the amount of charge it will
accept decreases, untill at 14.6 volts or whatever is designed as full
charge, it will no longer accept ANY charge. As the load changes, the
alternator provides more or less current as required to maintain the
fully charged voltage.

Clear as mud???

Bingo! Thank you. Exactly what I and Xeno have been saying and now
we have a mechanic confirming it.

On Sunday, June 23, 2019 at 6:54:52 PM UTC-4, Commander Kinsey wrote:
On Sun, 23 Jun 2019 17:53:21 +0100, trader_4 wrote:

On Sunday, June 23, 2019 at 12:27:13 PM UTC-4, TMS320 wrote:
On 22/06/2019 22:58, Commander Kinsey wrote:
On Sat, 22 Jun 2019 17:03:08 +0100, TMS320 wrote:
On 21/06/2019 21:19, Commander Kinsey wrote:

How does a lead acid battery charger (or car alternator) know when to
switch to trickle charge?

It doesn't.

Mine does, if I start my car when the battery is say 80% full, the
voltage will be 14.4V. After a while, something causes that voltage to
drop to 13.8, because something knows the battery is full and should no
longer be charged at a high rate.

I can understand it noticing a drop in
charging current if the battery is on its own, but what if a random
changing load is connected, as there is in a running car?

Ohm's law.

Explain how an alternator or charger can use ohm's law to distinguish
between:

To determine current, measure the voltage across a series resistor, duh.

1) A car battery which is full, with a load of 10 amps connected to it,
like two headlights.
2) A car battery with no load, which is not full yet and draws 10 amps
for the charge.

Two resistors?

The issue is not how it can be measured, the question is if any cars
actually do it, ie measure the current flowing into the battery and
use it to control the alternator. I've never seen it, never heard of
it. So far, all we have is Rod's flapping gums and he's made all kinds
of false claims and lies here.

And my claim that my car's alternator drops from 144V to 13.8V when the battery becomes full.

And he said they don't use a resistor,
that they just use the resistance of the battery cable. That doesn't
make sense to us, for obvious reasons. So, we're still waiting for
Rod to show us some documentation of what he claims cars do......

You do realise wires have resistance?

You do realize that the stupid Aussie troll who lies about most everything,
pontificating on some system, some method, does not mean that is what's
actually used? Show us some references or STFU.

On Sunday, June 23, 2019 at 8:12:53 PM UTC-4, Commander Kinsey wrote:
On Sun, 23 Jun 2019 14:53:00 +0100, trader_4 wrote:

On Saturday, June 22, 2019 at 5:58:02 PM UTC-4, Commander Kinsey wrote:
On Sat, 22 Jun 2019 17:03:08 +0100, TMS320 wrote:

On 21/06/2019 21:19, Commander Kinsey wrote:
How does a lead acid battery charger (or car alternator) know when to
switch to trickle charge?

It doesn't.

Mine does, if I start my car when the battery is say 80% full, the voltage will be 14.4V. After a while, something causes that voltage to drop to 13.8, because something knows the battery is full and should no longer be charged at a high rate.


Go find a description of the voltage regulator/alternator and/or a
schematic for that car.

No idea where to find that.

Give us the references. If something is telling
the VR/alternator what voltage to target, then there must be an additional
wire or connection of some kind.

Agreed. And it could well have a sensor in the fusebox etc.

I have not seen that. The other possibilities
are that the VR itself lowers the target voltage, based on? Makes no sense
and I've never seen it mentioned anywhere. I just googled for VR and looked
at half a dozen references, all just say the VR targets a specific voltage
period. The other possibility is that when you read the voltage later,
some other load is present that is lowering the system voltage that you see.

No, all I did was to start the car when the battery was almost full. The battery terminal voltage was immediately 14.4V. 20 minutes later it dropped to 13.8V. I added no loads.

Just because YOU added no loads doesn't mean the loads in the car are
not changing.



I think it actually dropped gradually if that means anything. I actually did that test because someone in one of these groups (although some troll has deleted half the groups, so I've added them back in AGAIN) told me that a car alternator changes voltage, this was in a post 6 months ago.

Given that it's typically a dumb, passive component device, that seems
unlikely. And if it's true, then there should be plenty of discussion
about it at online resources, yet so far, neither you nor Rod can
produce anything.




I can understand it noticing a drop in
charging current if the battery is on its own, but what if a random
changing load is connected, as there is in a running car?

Ohm's law.

Explain how an alternator or charger can use ohm's law to distinguish between:
1) A car battery which is full, with a load of 10 amps connected to it, like two headlights.
2) A car battery with no load, which is not full yet and draws 10 amps for the charge.

Rod claims that they have an extra sensing wire at the battery terminal
and use the voltage there versus the voltage at the other end of the
cable, to determine the current. I seriously doubt that, for obvious
reasons involving the very large gauge cable and current of interest.

It could only be mV, but easy enough to sense with modern electronics. Or how about an amp clamp?

How about you stop speculating and show us some references?




And he can't produce a damn thing from anywhere that says that's what
they do, except his own worthless statements. If it's done that way
anywhere, it's not done on the cars I've seen here, that have just one
battery cable on the positive terminal.

Every UK car has 2 or 3 cables on the battery positive. America is infamous for being behind the times.

Yeah, the UK is a real powerhouse in the auto industry, what with Triumps
that fell apart and all.

On Mon, 24 Jun 2019 02:42:39 -0700 (PDT), tardo_4, another mentally
challenged, troll-feeding, senile Yankietard, blathered again:


And you're the one that keeps going on and on about things he's said.
You're trolling him, I'm arguing and discussing with him.

Feel free to get a room with the asshole. He's the troll, not me. Arguing
is exactly what the troll wants. There is nothing to argue about. Rod
made some specific claims, I asked for any references to back it up, he
has come up with NOTHING. Capiche?

LOL What a FARCE!

On 24/6/19 7:42 pm, trader_4 wrote:
On Sunday, June 23, 2019 at 7:11:16 PM UTC-4, Clare Snyder wrote:
On Fri, 21 Jun 2019 13:48:56 -0700, % wrote:

On 2019-06-21 1:19 p.m., Commander Kinsey wrote:
How does a lead acid battery charger (or car alternator) know when to
switch to trickle charge?Â* I can understand it noticing a drop in
charging current if the battery is on its own, but what if a random
changing load is connected, as there is in a running car?

the catalytic converter tells it
I can tell you how an alternator does it, chargerscan do it
differently. AN alternator doesn't "switch to trickle charge". AN
alternator limits the output voltage. A battery will only accept a
certain amount of charge at any voltage. At 14.6 volts it basically
stops taking a charge. The regulator is set to limit the voltage to a
specified voltage - 13.8 or 14.2, or something similar. An alternator
is intrinsically current limitted so will not provide more than the
rated current, If the battery open circuit voltage is below 12 volts
it will tale pretty close to whatever the alternator can put out, as
the open circuit voltage increases, the amount of charge it will
accept decreases, untill at 14.6 volts or whatever is designed as full
charge, it will no longer accept ANY charge. As the load changes, the
alternator provides more or less current as required to maintain the
fully charged voltage.

Clear as mud???

Bingo! Thank you. Exactly what I and Xeno have been saying and now
we have a mechanic confirming it.

We had a mechanic confirming it when I was saying it since I am also a
mechanic. Served an apprenticeship and been in the trade since the 60s.
;-)

--

Xeno


Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)

On Mon, 24 Jun 2019 02:42:15 -0700 (PDT), tardo_4, another mentally
challenged, troll-feeding, senile Yankietard, blathered again:


says it. Collecting the quotes and repeating them over and over just
makes you more of a troll than him.

No, it documents that he's a lying asshole that's wrong about many things,
adamantly asserting his ignorance and will never acknowledge when he's
wrong. But feel free to argue with the troll. He's like a pig in the
mud, he enjoys it and doesn't care that he's proven wrong.

LOL Feel free to continue having a "conversation" with BOTH trolls,
troll-feeding idiot!

On Mon, 24 Jun 2019 02:42:29 -0700 (PDT), tardo_4, another mentally
challenged, troll-feeding, senile Yankietard, blathered again:

you were asking about, from everything I've seen does not. And Clare a
retired auto mechanic just told you the same thing.

Good Lord! For how long is this **** still going to go on? Until the troll
is so overfed that HE will stop it himself?...until the time when he baits
you senile fools with yet another idiotic thread? tsk

On Mon, 24 Jun 2019 02:43:13 -0700 (PDT), tardo_4, another mentally
challenged, troll-feeding, senile Yankietard, blathered again:

FLUSH the obviously mentally handicapped troll-feeding senile Yankietard's
latest troll-feeding ****

On Mon, 24 Jun 2019 02:42:59 -0700 (PDT), tardo_4, another mentally
challenged, troll-feeding, senile Yankietard, blathered again:


You do realize that the stupid Aussie troll who lies about most everything,
pontificating on some system, some method, does not mean that is what's
actually used?

You do realize that you are talking to a TROLL about another troll? Or does
your senility prevent you from seeing it? LMAO

On Monday, June 24, 2019 at 6:06:50 AM UTC-4, Xeno wrote:
On 24/6/19 7:42 pm, trader_4 wrote:
On Sunday, June 23, 2019 at 7:11:16 PM UTC-4, Clare Snyder wrote:
On Fri, 21 Jun 2019 13:48:56 -0700, % wrote:

On 2019-06-21 1:19 p.m., Commander Kinsey wrote:
How does a lead acid battery charger (or car alternator) know when to
switch to trickle charge?Â* I can understand it noticing a drop in
charging current if the battery is on its own, but what if a random
changing load is connected, as there is in a running car?

the catalytic converter tells it
I can tell you how an alternator does it, chargerscan do it
differently. AN alternator doesn't "switch to trickle charge". AN
alternator limits the output voltage. A battery will only accept a
certain amount of charge at any voltage. At 14.6 volts it basically
stops taking a charge. The regulator is set to limit the voltage to a
specified voltage - 13.8 or 14.2, or something similar. An alternator
is intrinsically current limitted so will not provide more than the
rated current, If the battery open circuit voltage is below 12 volts
it will tale pretty close to whatever the alternator can put out, as
the open circuit voltage increases, the amount of charge it will
accept decreases, untill at 14.6 volts or whatever is designed as full
charge, it will no longer accept ANY charge. As the load changes, the
alternator provides more or less current as required to maintain the
fully charged voltage.

Clear as mud???

Bingo! Thank you. Exactly what I and Xeno have been saying and now
we have a mechanic confirming it.

We had a mechanic confirming it when I was saying it since I am also a
mechanic. Served an apprenticeship and been in the trade since the 60s.
;-)

--

Xeno


Oh, didn't know that. There may be a different, more advanced charging
system on some new cars, but no one has been able to show it or why
it would be used. And meanwhile making claims about it, how it works,
is just the usual BS. And we know the basic alternator/VR system that
just targets a voltage has worked for the better part of the last century.

On Mon, 24 Jun 2019 12:13:22 +1000, Xeno
wrote:

On 24/6/19 9:45 am, Clare Snyder wrote:
On Sun, 23 Jun 2019 12:05:52 +1000, Xeno
wrote:

On 23/6/19 1:57 am, Rod Speed wrote:


"trader_4" wrote in message
...
On Saturday, June 22, 2019 at 6:00:41 AM UTC-4, Brian Gaff wrote:
Yes indeed, the nominal output of an alternator can be as high as 15
volts,
but even a fully charged car battery is only 13.8v as far as I know and
these days, I'm sure the direction of current flow and voltages are
monitored very well by the computers. In the old days it was a bit of a
black art just relying on the ability of the alternator or dynamo in
the old
bangers.

Nonsense.* Cars used voltage regulators for better part of a century and
they are simple electronics which is well understood.* And, AFAIK,
that is STILL how it's done, all the FUD here notwithstanding.* Some
cars may have something more elaborate, but it's obviously not required
to keep the battery correctly charged, which was the OPs question about
charging.

No it wasn’t, he asked about changing to a trickle charge when the battery
is fully charged.

Battery chargers do it automatically - if they are decent.
Alternators too do it automatically.
SOME chargers - and some vehicles that use the computer to control
charge, use a "3 step" algorythm which uses constant current to "bulk
charge" the battery to a certain level, then switch to constant
voltage untill output current drops below a certain point where it
switches to "float charge". Not COMMON on cars, but getting pretty

A car charging system is unlikely to ever really *need* a float charge
mode since it has to deal with other electrical system loads as well as
the needs of the battery. That and the type of use the car battery gets
adds a layer of complexity to it all that I can't see is really
warranted. A battery charger, on the other hand, has to deal only with
one load, the battery.

common on higher end chargers to prevent overcharging and gassing of
the battery when left on charge. The old service station type chargers
had a simple timer to accomplish this - and some of the later ones had
a combination - when charging voltage exceded a certain point it would
charge for anothe X number of minutes before shutting down.



Automotive charging systems that actually sense current are
EXCEDEINGLY RARE.

I've never seen one.



GM and Honda are examples of charging systems that use a device to
monitor the battery voltage and current flow.

GM uses a battery sense module on some applications, which is
typically mounted to one of the battery cables. The sensor module uses
a Hall Effect sensor, which provides a 128 HZ PWM signal to the BCM
(Body Control Module). The sensor stays powered up even when the key
is off, so the BCM can identify parasitic drain.

Honda applications use an electrical load detector (ELD), which is
typically located in the underhood fusebox. The function of the
electrical load detector is very similar to a battery sense module.

The PCM supplies five volts to the electrical load detector. The
electrical load detector grounds the circuit, providing a voltage
signal between 0.3–4.50 volts to the PCM. The higher the voltage, the
lower the charging system output, while a lower voltage indicates a
higher charging system output


GM and Ford use a different strategy, where the computer monitors
feild current (actually feild voltage, but the voltage across a fixed
feild resistance yeilds a current measuremnt and by computation
deduces what the output current is.

On 23/06/2019 23:55, Commander Kinsey wrote:
On Sun, 23 Jun 2019 17:27:09 +0100, TMS320 wrote:

On 22/06/2019 22:58, Commander Kinsey wrote:
On Sat, 22 Jun 2019 17:03:08 +0100, TMS320 wrote:
On 21/06/2019 21:19, Commander Kinsey wrote:

How does a lead acid battery charger (or car alternator) know when to
switch to trickle charge?

It doesn't.

Mine does, if I start my car when the battery is say 80% full, the
voltage will be 14.4V.* After a while, something causes that voltage to
drop to 13.8, because something knows the battery is full and should no
longer be charged at a high rate.
*
I can understand it noticing a drop in
charging current if the battery is on its own, but what if a random
changing load is connected, as there is in a running car?

Ohm's law.

Explain how an alternator or charger can use ohm's law to distinguish
between:

To determine current, measure the voltage across a series resistor, duh.

Why didn't you wait until I'd finished?

You asked.

1) A car battery which is full, with a load of 10 amps connected to it,
like two headlights.
2) A car battery with no load, which is not full yet and draws 10 amps
for the charge.

Two resistors?

Yes that would work, but not if it has no external sensors (as in
external to the alternator).

An alternator is not simply two wire power output. The electronics on
the alternator would be to keep everything within acceptable parameters
but fine control comes from the ECU.

On Mon, 24 Jun 2019 16:33:08 +0100, TMS320 wrote:

On 23/06/2019 23:55, Commander Kinsey wrote:
On Sun, 23 Jun 2019 17:27:09 +0100, TMS320 wrote:

On 22/06/2019 22:58, Commander Kinsey wrote:
On Sat, 22 Jun 2019 17:03:08 +0100, TMS320 wrote:
On 21/06/2019 21:19, Commander Kinsey wrote:

How does a lead acid battery charger (or car alternator) know when to
switch to trickle charge?

It doesn't.

Mine does, if I start my car when the battery is say 80% full, the
voltage will be 14.4V. After a while, something causes that voltage to
drop to 13.8, because something knows the battery is full and should no
longer be charged at a high rate.

I can understand it noticing a drop in
charging current if the battery is on its own, but what if a random
changing load is connected, as there is in a running car?

Ohm's law.

Explain how an alternator or charger can use ohm's law to distinguish
between:

To determine current, measure the voltage across a series resistor, duh.

Why didn't you wait until I'd finished?

You asked.

No, I said "explain.... distinguish between:" and before I'd listed the two things, you interrupted.

1) A car battery which is full, with a load of 10 amps connected to it,
like two headlights.
2) A car battery with no load, which is not full yet and draws 10 amps
for the charge.

Two resistors?

Yes that would work, but not if it has no external sensors (as in
external to the alternator).

An alternator is not simply two wire power output. The electronics on
the alternator would be to keep everything within acceptable parameters
but fine control comes from the ECU.

So there are external sensors.