New AGM Batteries - Winter Storage

[max-on]

Ok, this year I replaced the old batteries, which I left on the boat last winter as they were no longer holding a charge, with new Lifeline AGMs (Group 24 and Group 30).

For winter storage in Rhode Island, I guess I should remove the batteries from the boat and take them home. Do I need to charge them at home, or can I let them sit without charging? If I need to charge them, any recommendations for a charger?

[camaraderie]

Charge them fully then take them home. You should not need to re-charge them over the winter, (check w/ a voltmeter monthly), but throwing on a bulk charge with a standard auto charger once or twice for a few hours won't hurt anything.

[max-on]

Thanks Cam, that is what I was thinking, but being the batteries are new, I did not want to do, or not do, something because I did not ask.

[Quickstep192]

Last year, I added an on-board automatic charger to keep them charged over the winter so I wouldn't have to lug them off of the boat. This is what I got.

http://www.marinco.com/scpt/ProdPage...20Recreational

[haffiman37]

Where You store them is of less importance. It might be in the boat or at home providing they are stored in a 'cold' place. The higher the temp, the more self discharge. But see to that they are fully charged before storage.
For quite some years I used to take the batteries out of the boats in winter storage, but stopped.
Fully charged batteries generally went down to 60% when stored inndoors 4-6 months, when stored in the boats outside they went down to 80%. Just disconnect the battery cables.

[sailingdog]

QS-

A lot of places won't let you leave the charger plugged in, since a majority of winter storage fires are started by boats that were plugged in.

What is probably a better idea is to plug the boat in a couple of hours a week or so. If you live near the marina or where your boat is being stored, that is probably the safest for both the boats and your batteries.

Originally Posted by Quickstep192

Last year, I added an on-board automatic charger to keep them charged over the winter so I wouldn't have to lug them off of the boat. This is what I got.

http://www.marinco.com/scpt/ProdPage...20Recreational

[Vasco]

We never take the batteries home. Charge them up and leave them on the boat. It's a waste of time and effort taking them out especially AGM's that seem to self discharge less than flooded batteries. You're more likely to damage them by dropping them going up and down the ladder than by just leaving them aboard.

[btrayfors]

"Fully charged batteries generally went down to 60% when stored inndoors 4-6 months, when stored in the boats outside they went down to 80%. Just disconnect the battery cables."

This is a sure way to ensure sulfation of the plates and consequent deterioration of the battery's capacity.

AGM's have a self-discharge rate of 1-3% per month; flooded batteries can self-discharge as much as 15% a month. Thus, AGMs can be left without a charger considerably longer than flooded batteries without incurring permanent damage from lead sulfate crystal (PbSO4) buildup. However, both types need to be kept at near-full charge to prevent deterioration.

Keep them charged, any way you can.

Bill

[max-on]

So, is the concern self-discharge and keeping the batteries topped-off, or does the concern also include freezing temperatures?

[TrueBlue]

A fully charged battery will not freeze. I've been keeping my 4D wet cell banks onboard for the fourth haulout season now. Not about to bust my balls hauling those monsters off the boat. They were 3 years old when I bought the boat, never been trickle or booster-charged through the winter and have not shown any signs of loosing life during season.

It's more important to have them fully charged at layup and disconnect all terminals from the battery posts. I wouldn't worry much about the low temps around Narragansett Bay, max. The temps rarely get to the teens, let alone single digits - even at night and if so, it warms up during the day.