Battery test

[Albesaurus]

Excuse my lack of DC knowledge. My two batteries ( start and house) are on my bench all winter. I have put a charge on them every two months. Now I’m putting them back on the boat. I did have a few episodes last season with my starting battery loosing charge while on the hook ( 4-5 hours) so i had to switch to get running again. I run nothing on the hook besides the head, pressure water and the Garmin plotter.

They both charge up to 13.6 volts. Then just an hour or two later with zero draw. They settle back to 12.5 and 12.6. As per the meter. This is off the boat on the bench. that normal?

[Tree]

Sounds normal to me

[Tree]

Out of curiosity. What batteries do you have - some batteries require “special” charging, like AGM for example.

[Albesaurus]

](Out of curiosity. What batteries do you have - some batteries require “special” charging, like AGM for example.)

Interstate deep cycle and powervolt Heavy duty

[jleonard]

Here's a little chart that I have used.
Hope it helps a bit.

battery-state-of-charge.jpg

[Albesaurus]

Thanks for the reference chart. Both my batteries are holding 12.6 for a few days now. As a side note i see now that they Manufactured in 2011! So nine years old

[Tdelaney]

If you had one die last year, time to replace at that age. I would start wit the starting battery first. I went through the same thing 2 years ago.
Tom

[Norseman]

Thanks for the reference chart. Both my batteries are holding 12.6 for a few days now. As a side note i see now that they Manufactured in 2011! So nine years old

I got maximum 6 years out of lead acid boat batteries in Florida.
(Rolls batteries may go longer.)
Anything beyond 5-6 years is a gamble, roll the dice..

[Tree]

Thanks for the reference chart. Both my batteries are holding 12.6 for a few days now. As a side note i see now that they Manufactured in 2011! So nine years old

I got maximum 6 years out of lead acid boat batteries in Florida.
(Rolls batteries may go longer.)
Anything beyond 5-6 years is a gamble, roll the dice..

Interesting you’ve Rolls batteries over there. They’re a superb battery but it is important you charge those at 14.9v and not the usual 14.6v most chargers put out - it’s something to do with how tight the plates are inside or something along those lines.

[DCatSea]

This might seem a bit simplistic, but do you check the electrolyte levels when you take the batteries out, and before bench charging. An old diesel/electric submarine routine was to run the batteries (all 800 tons of them) to almost empty, then trickle charge for as long as it takes to get back up. They'll get warm so you'll need to keep an eye on them. If memory serves well this was called an equalizing charge. Distilled water is readily available at your friendly local pharmacy,

I check electrolyte levels monthly just to be safe, and the current batteries were first installed in 2016. Having said all this I know this will be the year when they let me down.

[Norseman]

. If memory serves well this was called an equalizing charge.

We do an equalization charge once every 2-3 months:
Bring the batteries up to way over normal voltage to clean the plates and burn off sulfides. (Forgot the exact science but it is a good idea on old lead acid batteries.)
Most chargers have an equalization mode, just make sure there is plenty of distilled water in the batteries as they will boil at the high voltage.