Battery Storage.

[Pat K]

Here is something I posted several years ago. With a battery failure thread going in the Snow Mobile section I thought you might find it interesting.

 

Many years ago a co-worker did his own battery storage test. When he bought a new set of batteries for his 24v trolling motor he labeled the batteries and stored battery A in the boat in my unheated pole shed. This is MN so it saw sub-zero temp regularly. Battery B was stored in the utility room of his town home. He prepared them for storage by removing all wires, topping off fluids and charging them then forget about them for the winter. Every spring he tested the batteries and the cold storage battery was always a few tenths of a volt higher than the warm storage battery. Both of them still had 85-90% of their charge.
He was a retired electrician and believed anyone who charged a battery inside of their house was a prime candidate for a Darwin award because of the explosive gasses that can result from charging the battery.
Battery B that was stored inside failed midway through its 6th season. Wynn worked part time and fished most of the rest of his time so they had heavy use. Battery A was moved to his ice house and lasted a couple more years.
Not a big enough sample to prove anything but I still find it interesting.

 

I always just disconnect the ground connections from the batteries in my boat and leave them in the boat. I do hook a charger up to them around Feb 1st and it only takes 15 to 30 minutes for them to be completely charged. I've never had a battery freeze during the winter in 38 years of boat ownership.

 

[BobT]

When it comes to battery life, heat is a battery's enemy, not cold. A fully charged lead-acid battery is safe down to about -90 F. At 60% charge it is good down to about -15 F so when storing in cold climate it is best to periodically connect them to a charger to top them off. 

I personally am not a fan of maintenance chargers because they don't always realize when a battery is at full charge. This can be especially true for an older battery that has lost some of its capacity. This is because even a new battery never charges to the point where its resistance gets to infinity so it will allow some small current continue to pass and the charger can be fooled into thinking the battery is not yet fully charged. This small continuous current results in warming the battery fluid and can cause evaporation of the electrolyte and that is not good. If you use a maintenance charger, be sure to periodically check your electrolyte levels and top off as needed.

 

 

[RebelSS]

Except for AGM (glass mat) batts. They're sealed.