Here, educate yourself;
https://www.swtc.edu/ag_power/electr...l_circuits.htm

I knew all that before you were even born, thanks.

so it is still a load even when fully charged.

Not when its still taking 4A,

If the battery is *taking* 4 amps, then it *is definitely the load*.

But it wont be taking 4A WHEN THE BATTERY IS OUT OF THE
CAR WITH A BENCH SUPPLY. Because the battery voltage will
have risen once it has been charged so the original 4A will
have dropped significantly WITH A BENCH SUPPLY.

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

It has more than one wire to the positive terminal of the battery.
So it can see what current is going to the rest of the car.

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.

No they aren't, unless one has been added.


--
Bod

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus