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 and alternators with basic voltage regulators 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.




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





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".





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? Alternators with voltage
regulators have been used with lead-acid batteries in cars for the
better part of the last century. And the principles with generators
are the same.





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. We can point you to many auto websites which will
explain it, how it simply uses an alternator and a simple voltage regulator..
So here's an idea. You provide us some references that show the
more elaborate method that you claim is actually what is used
today in all cars. And why it's needed when the other system works.
????????