Winter Battery Care and Feeding

[beckys]

Hi all -- been reading a lot about batteries and the proper care and feeding but I'm still very much a newbie so much of the tech talk is a bit over my head. I put new AGM batteries into our AS and just finished winterizing the plumbing. The AS will not have shore power where we are storing it for the winter. I put the battery in store mode. We have 2 solar panels. Question is this: In store mode will the solar panels still maintain the batteries a bit? Should I take the batteries out and put them on a trickle charger for the winter? And bring them back out with me if I want to stay in the AS for a weekend?

If you recommend taking them home and putting them on a trickle charger, do you have a favorite brand for AGMs? Thanks!

[DaveP]

Lifeline AGM batteries are the gold standard. They should be fine in the trailer with the solar panels charging them given your mild winters in Seattle. If the solar charger is hooked directly to the batteries, they should continue to charge. Also, AGM batteries in general have a very slow leak-down rate in storage without any load.

[jeffmc306]

Our Globetrotter has the factory solar and AGM batteries. I decided to leave the batteries in the coach this year since I installed a Victron BVM-712 and a Blue Sea disconnect switch last summer.

We got our first measurable snow last week then ice and more snow. I checked the BVM-712 monitor today and saw the battery voltage was getting low. I tried to brush the snow off the panels but can’t get through the layer of ice.

I have a PulseTech dual battery maintainer and found a way to install the unit under the propane cover and run the cables out the bottom and through the side of the battery box. I disconnected the negative cable connecting the two batteries so they’re isolated and turn the Blue Sea disconnect to off and connected the battery maintainer.

Everything is buttoned up and out of the weather. The PulseTech unit will desulfate the batteries while charging then go into maintain mode. Much easier than removing the batteries.

[Daquenzer]

I would be concerned in Seattle with enough sun light in the winter.

[jeffmc306]

I got the folding ladder out today and broke through the snow-ice-snow layer on the roof and uncovered the solar panels. It’s been cloudy for days so once we do get some sun they’ll melt off the remaining stuff. The PulseTech maintainer has the two AGM batteries back to 100% so no worries.

[ROBERT CROSS]

Originally Posted by Daquenzer

I would be concerned in Seattle with enough sun light in the winter.

Our Lifelines AGM's lasted 11 Seasons here in the WNY snow belt, charged fully, disconnected and left in the AS.
No significant loss if disconnected & fully charged.
Still in service as sump pump back-up.👍

Bob
🇺🇸

[BayouBiker]

Not much to add about practicality of maintaining batteries with solar.

I do have some comments about batteries not in use in general.

1. Batteries last longest when not actively cycled (charged and discharged)
2. The greatest factor is the depth they are discharged when cycled, thus if you cycle them to 100% Degree of Discharge (DOD) you will get about 250-350 cycles from an AGM, 600 cycles at 50% DOD, 1800 cycles at 20% DOD and about 4000 cycles at 1-3%
3. Ok so on a solar charger (cycles daily) with parasitic loses (propane monitor, inverter, any digital attached accessories with remotes etc.) you're taking about 3-5% off the life of the battery after adjusting for cloudy days and whatnot vs. removing the batteries and storing them in a cold location (near freezing is ideal) for the winter. Not a lot, but not insignificant either.

So removal/complete disconnect or a maintenance charger are the best ways to go.