On Sat, 22 Jun 2019 19:14:07 +0100, Rod Speed wrote:



"Bod" wrote in message
...
On 22/06/2019 18:02, Rod Speed wrote:


"trader_4" wrote in message
...
On Saturday, June 22, 2019 at 11:45:19 AM UTC-4, 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.

Not on any car I've owned or worked on. And more to the point, it's
obviously not needed because cars have worked with the same lead-acid
batteries

They arent the same lead acid batterys, most of the current
ones cant be topped up with extra water when needed.

and alternators with basic voltage regulators for most of the last
century.

We havent used alternators for most of the last century.

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.

Even if there is an additional wire, explain to us how you
monitor the current in the charging cable with that wire.

With more than one wire, you can see
what the load from the lights etc is.

And you dont even have to do it that way
with modern computer controlled lights now.

And Rod is talking computers,

Because thats what his car has.

But the essence of his question is how cars switch to
trickle charge and AFAIK, the answer is they don't.

The current to the battery does in fact drop
dramatically once the battery is fully charged.

Again, the battery, alternator output and
all the car loads are connected TOGETHER.

Irrelevant to what can be done with
the voltage from the alternator.

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.

And that's all that's needed to keep the battery correctly
charged and working. There was no "trickle charging".

There is in the sense that the current to the battery
drops significantly when the battery is fully charged.
Yes, he didnt word the original very well, but thats
what he always does.

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.

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,

Any other obfuscation you want to throw in?

You never could bull**** your way out of a wet paper bag.

Alternators with voltage regulators have been used with lead
-acid batteries in cars for the better part of the last century.

Wrong, as always.

And the principles with generators are the same.

Wrong, as always. With an alternator you can regulate its output
by varying the exciter current. You cant do that with a generator.

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.

Xeno and I have correctly described how the basic, widely used charging
system has worked for decades with the same lead-acid batteries.

They arent the same lead acid batterys.

Rod, you keep spelling *batteries* incorrectly

Wrong, as always.

(just to let you know).

No news to me, boy.

He's probably as old as you.