Sorry, its another battery thread,
I've read loads on here about looking after batteries including "Wotever's" battery primer thread several times and I think I'm getting my head round things.
Does the following make sense ?
We've been on hook up in the marina for the last two months but started to get a bit "marina crazy" so have gone out cruising for a few days and decided to try and analyse the state of our batteries.
We have a nominal 520ah bank and I turned the engine off at 7.45 last night with the mastervolt panel showing a 5.3 A charging current, making them fully charged from what I've read.
This morning (7.45) so a full 12 hours later, the voltage was at 12.45v so battery bank at 75% with mastervolt panel saying we had used 52ah.
Some simple maths suggests that total bank capacity is now 208ah, i.e. 52 x 4 assuming the 52ah used is 25% of the capacity.
The boat was new to us last march so have no idea how old the batteries are or how they have been treated in the past.
My musings from the above is that the batteries are on their way out but as we will be back on hook up for the next two months, its not a issue at the moment and I might be able to squeeze another summer out of them when solar starts working again.
Does the above sound about right or is there a fundamental flaw in my thinking ?