"trader_4" wrote in message
...
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? 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.
;-)

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

The OP clearly has with his 2002 Renault. Hardly a new car.

or why it would be used.

To avoid over charging the battery, ****wit.

And we know the basic alternator/VR system that just targets
a voltage has worked for the better part of the last century.

Alternators were no in fact used for the best part of the last century.