On Sat, 27 Jun 2020 17:08:27 -0400, Paul
wrote:

snip

https://www.briandorey.com/post/low-...-using-max8212

https://datasheets.maximintegrated.c...11-MAX8212.pdf

The leakage current isn't zero, but it's a relatively simple circuit.

The version here is non-recovering, and you press a reset button
after a battery-rundown event. Not very convenient.

https://www.maximintegrated.com/en/d...tes/9/926.html

The chances are there is something like that built into the charge
controllers you referenced (there certainly was in the one with two
USB outlets as that's the one we used for a couple of years).

I went to turn the electric fence off and found it was already off.
Then I checked to battery voltage (LCD display) and realised why (it
had gone into LVD mode and it hadn't been sunny enough, long enough to
re-trigger it again).

When I was looking for a suitable charge controller (again, really for
the LDV function) I was looking for something 'lightweight' that might
have a correspondingly low parasitic load but couldn't find anything.

The thing is, if the charge to total load capability it's sufficient
to stop the battery flattening in the first place, not having it auto
reset may still be 'better' than destroying a battery?

I have re-cycled too many 'brand new, used a couple of times'
batteries from motorcycles and other roles from lack of maintenance to
know I'd rather avoid that over anything else.

Cheers, T i m