AGM Storage

[belizesailor]

This season is my first experience managing an AGM house bank, very different than my previous gel bank. Rainy season is upon us and its time to think about putting the boat to bed. Im looking for input for best storage practices for AGMs.

My configuration: 375W solar with a Blue Sky 3000i controller (very configurable). Also 2x65A engine driven alternators. House bank: two LifeLine 8Ds (510Ah total).

Boat will be stowed on a mooring so I want batteries charged in case bilge pumps etc are needed.

LifeLine's recommendation for storage assumes disconnected batteries: fully charge, stow in cool dry environment (yeah right, Im in the Tropics), top up charge every 3 months.

That doesnt fit my circumstances, so looking for best practices re charge regime for about 6 months with batteries connected. Normally no load except maybe occassional use for tending to boat and bilge pumps if needed (dry boat, so no regular bilge pump runs).

Thanks in advance.

[Privleoplag]

I'd consider doing one of two things.. just leave as is, let the controller do it's job. Or, if you have a sealed start battery, charge up the house, disconnect the 8d's, put the start battery in their place and let the solar controller do it's job.
Hopefully, you won't develop a leak that needs the bilges running all night. But, that's what we all hope isn't it.

[billknny]

If your solar controller is set for the proper float voltage recommended by your battery maker, you should be all set.

I'd probably also configure the controller so the absorption voltage matched the float voltage so it just stayed right there all day with no chance for overcharging.

[belizesailor]

Originally Posted by billknny

If your solar controller is set for the proper float voltage recommended by your battery maker, you should be all set.

I'd probably also configure the controller so the absorption voltage matched the float voltage so it just stayed right there all day with no chance for overcharging.

Yeah, thats similar to my thoughts too, basically a constant voltage charge. Used to do that w my gels, but AGMs are new territory for me.

[belizesailor]

Originally Posted by Privleoplag

I'd consider doing one of two things.. just leave as is, let the controller do it's job. Or, if you have a sealed start battery, charge up the house, disconnect the 8d's, put the start battery in their place and let the solar controller do it's job.
Hopefully, you won't develop a leak that needs the bilges running all night. But, that's what we all hope isn't it.

Have automatic relays for starts so they should be good. They are sealed, but as long as I keep max volts in range they should be good.

510Ah should be good to run bilges all night if needed!

[a64pilot]

Originally Posted by billknny

If your solar controller is set for the proper float voltage recommended by your battery maker, you should be all set.



I'd probably also configure the controller so the absorption voltage matched the float voltage so it just stayed right there all day with no chance for overcharging.

This is your answer, set it so absorption and float are both 13.3.
There is very little charging at float voltages, but your using if anything, very little energy.
Maybe bump to 13.4 if you are temp corrected, that is within allowance.
I’d put them through an equalization before storage if possible, and again maybe after storage.