Camping in the Cold--Some AH Figures

brulaz wrote:

BFL13 wrote:

...
OK so by Wednesday morning, down 292 AH by Trimetric, "morning voltage" is 12.1 so if that is half, full must be 584. Yipes , kind of low, but you do take a hit in the cold.
...

Think that 12.1V ~= 50% SOC is at ~25C.

And there's different SOC vs V charts depending upon your mood.
But think they all indicate that at lower temps 50% SOC is at a lower V? If so, at 0C, 12.1V might actually indicate you are closer to 60% SOC.

Then back calculating from that 50-60% SOC (and your Trimetric) makes for a really poor estimate of your bank's capacity.

And are you really using 292 Ah per day? Or was that from Monday to Wednesday?

LY, no. The AGM is in the truck camper and has only floated so far.

Got that because the flooded one in there was gassing a bit and setting off the LP alarm. The battery box (under the step up to the bed ) is inside, not really vented. The AGM has cured that problem. The TC usually has 15a shore power where it goes, so not expecting to give the AGM much of a work-out.

It would be interesting to have some more of those AGMs in the 5er to test them out. One thing is I could keep them inside where it is warm and effectively gain a bunch of AH in winter just from that!

-- Actual capacity is always an estimate, but I did IMO accurate load tests last year and then you play with the temperature/capacity charts which are not all the same. I also go with the recharging patterns for consistency over the years doing the same thing and it all comes together fairly well looking at all the evidence.

---Follow up on OP, this morning just before top-up recharge, "resting" was 12.3, down 227AH, so 227-78 = 149 used. No attempt being made to save battery. Idea is to have enough set-up so no change in "lifestyle." "Lifestyle" takes about 60AH and the rest is furnace. No solar here in the woods to help. No problem--that's what the Honda is for. :)

--I don't know about volts vs SOC being different in the cold. I did read that batts need higher voltage to recharge them when it is cold.
Note the 15+ voltages in the OP I set as temperature compensation. 14.8 is 15.2 in these temps. Gottaluv adjustable voltage chargers! :)