KyleR wrote:Source of the post ... I discovered when going through the systems. These batteries had a label that said "Remove this label when installed to monitor electrolyte level" (or something like that). The label had never been removed (i.e. no way to check level with label on) and the batteries had been installed in 2020. So again they were definitely neglected. Thankfully when I checked the level everything looked good - with no plates uncovered. ...
It's quite possible if there was absolutely no electrolyte lost in 3 years that those batteries might have never (or rarely) been fully recharged. This is very bad for lead-acid batteries. If you constantly only recharge to 90 or 95% you lose a lot of capacity over time. This is very different than, say, Lithium batteries which really LIKE not to be 100% charged.
Swing by a Harbor Freight and buy one of their digital volt meters. They're cheap ($12?) but they work just fine. Buy two and leave one at the house and one on the boat.
And those battery voltage charts are just general. The actual voltage depends a bit on the chemistry, as there's additives to the plates that can swing it up or down by a bit. And the charts really only apply to new or fresh batteries, not over their whole useful life. The voltages will gradually decrease a bit as the battery ages.
bud37 wrote:Source of the post ....
One fridge at 8 amp draw running for 15 minutes twice an hour would pull 16 amps for the 1/2 hour....8 amps for the hour....therefore 8ah......divide 105ah by 8ah = 13 hours of use. ...
Might want to double-check that math. If a fridge has an 8 Amp draw, then it would use 8AH for every hour it's running. If it's only running 50% of the time, then that would be about 4AH for every hour that passes. By that math, a bank capable of 105AH should be able to run that fridge 26 hrs. (just the fridge).