Worried about voltage

[Beanyboy57]

So I think the culprit, here, isn't the batteries ... it's the godamn inverter, which I suspect is probably pulling something like a couple-six amps, even when "off."

I had the same problem with a cheap MSW inverter I initially purchased when first setting up my off-grid sytems, it was dragging huge amounts of power even when off and it was harming my batteries. I replaced it with a (much more expensive) better brand TSW inverter/charger and my problem was solved.
I also modified the connections between my batteries so that the power draw was evenly spread.

[inetdog]

PS: Charge controller's voltage reading is off by .3v - I had assumed it was right, the inverter was wrong. Turns out, the inverter was closer to accurate, and the charge controller's voltage was off: no wonder I thought the batteries weren't charging! I've tweaked the controller offset so the voltage readout is now accurate: The DVM suggestion was wise.

This is probably not a factor in your situation, but some CCs which include voltage correction for either ambient temperature or remotely sensed battery temperature will display the "equivalent" voltage after temperature correction rather than the real voltage. This, I suppose, is intended to allow you so look for the same voltages as "full charge" indicators even when the battery temp varies over a wide range. But if the manual does not tell you about this you can think that it is just an error in the display.

[Vern Faulkner]

Update No. 3

You may recall, about three months ago, I wrote to you worried over the specific gravity of the two heavy-duty Trojans I purchased last autumn.

I've done some research and it seems that Trojans, for whatever reason, "get stronger" after a time - the general specs are about 40 charge/discharge cycles. (Some of that research is here, btw.)

That lines up with my experience. About two weeks ago, I did a heavy-duty equalize cycle, starting with about three and a half hours on an inverter/charger (15.4 v at 11 amps), followed by two hours of higher-current charge off the charge controller (15.5 v at 12-17 amps). It seemed to me that the battery was "stronger," that is, it was holding voltage better for the same usage - usually about a 50 draw four hours each night is typical, yet I didn't notice a major bump in SG on any cells. A bit, but not much.

After another two hours of equalize charge today, the SG has increased, and just off two test cells, I read 12.72, which is a little less than full charge - and what I'd expect for almost 10 pm, when the inverter has pushed through, say, 16 amp-hours of juice. All liquid levels are still well above the top of the plates, I should note. I have not added water to any of the cells, yet.

Just an FYI. Seems, maybe, that the Trojan FLA batteries come from the factory a bit diluted, maybe? Certainly worth pondering the SG right from the get-go, and maybe worth a "commissioning charge," as I believe one poster called it.

So my auto-parts tester wasn't buggered, after all. The SG was low, right from the factory (!).

[Naptown]

I believe the Trojan manual states that full capacity is not available initially and it takes x # of cycles to acheive this.
Also if FLA batteries what you pull off the top for a test may be diluted due to battery stratification that was corrected by the equalization.