trader_4 wrote:
On Friday, June 21, 2019 at 4:54:51 PM UTC-4, Rod Speed wrote:
Commander Kinsey wrote

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

From the current the battery takes.

Except that the alternator doesn't know how much current is going
into the battery and how much is being used to power the car.
At least not in any car I've had. The alternator is tied directly
to the battery and that common point supplies the car. The alternator
can't switch to trickle charge either. EVery one I've seen, with
the car running normally, the voltage at the alternator/battery is
about 13.5 - 14V

Some better home chargers measure voltage, and temperature, and apply some
kind of program. My Chevy seems to cut off charge completely at times,
depending on some sort of program. That's scary cause looks like alternator
is bad.

Greg