PWM controller with no float

I have been charging AGMs with an MS SS-10 two stage controller for about two years. Yes the Volts stay at 14.4 or 14.1 Volts depending on the jumper, plus or minus with the temp compensation. The Amps do drop to insignificant values below 100ma.

With AGMs, there is no water loss at these values due to the built in valves.

HTH;
John

I'd rather have a proper float. The rest is easy.

I will take the daily 15 minutes at 14.x then 8 hours 13.3 float, and off at night over the constant 13.4 24/7 any day. IMO that short cycle is good for the battery.

Good for camping forever. Dubious as a maintainer for more than a few weeks IMO.

Sometimes Forum guys get to wondering whether solar storage maintainers that drop their voltages at night (as they must) are as good as shore power battery maintainers, which stay at 13.4v forever.

Mex says the constant float voltage is better than anything, but you do need shore power for that. So then you might ask, if solar is second best, how much farther off second best is that two stage thing?
I don't know.

BFL, the 14.4 is temp compensated, and the controller is mounted right behind the battery (shielded from it). I've seen as high as 14.8 on cool days already. So I'm pretty sure it would be 14.0 or whatever on a hot day. Not sure if this answers your objection, though.

It's part of a portable setup, so in reality it won't be used for long term storage. But I do wonder just how long I can get away with it.

It lets the voltage drop at night, so you don't get sustained 14+ volts.

Yes, 14+ it too high as a 24/7 float even with no amps, except when it is cold out
32F - 13.9v
15F - 14.2v
-5F - 14.4v

I think 14.4 all day during daylight would not be good in warmer temps in the long run. Agree with smk. Good for camping, not so good as a maintainer

I never did find out what my $13 RJ special does once the batts get charged up. Might be the same deal as that one. (Series type with constant voltage at the high set-point for Absorption while amps taper.)

You have a simple, single stage controller. You have a choice with a single stage

a) Charge the batteries at a ridiculously slow rate and avoid overcharge

b) Charge the batteries at a decently fast rate but then overcharge them
(boil).

THE CHEAP WAY OUT?
Buy a twelve hour wind up timer then give it your best shot at 14.4 volts. Heavy use? Then it'll be dawn till dusk. A voltmeter should be used. The days of non-use will be days of no charging unless you set the charger to float (see below) and bypass the timer.

Reset the charge rate to 13.3 for storage and let'r rip without the timer.

You COULD get overly clever and wire the timer so when you wind it up it BYPASSES a SILICON DIODE circuit feeding the battery. When the timer runs out, 14.4 volts minus .7 volts for the silicon diode voltage drop = 13.7 volts.

Hope This Helps

Yes, storage type situations are what concern me.

Fine for in use. I would not use it for storage.
JMHO