Winterizing Solar Batteries

[jrmillerjr]

Greetings,

My 2020 Basecamp X has the solar upgrade. I cannot seem to find recommendations regarding best cold-weather practice for the AGM batteries installed by Airstream with the solar panels.

I live in the mid-Atlantic, store outside in a spot that receives good morning to early afternoon sun, without shore power. The batteries are almost always at 100% when I've checked on them. While winters vary, we rarely see prolonged freezing temperatures.

Should I remove the batteries to store indoors and trickle charge as needed or leave connected in the Basecamp with the solar continuing to charge?

And, for what it's worth, I've had the Basecamp since August and have taken it on a few trips during which time it has performed flawlessly. No issues whatsoever!

Can't wait to spend more time in it... Jim

[Jim Flower]

Hi Jim,
I have four AGM batteries in my 2012 Airstream and about 400W solar. The batteries have been in place since 2012. They have never been out of the Airstream. I store outside all year and get subjected to nasty Canadian winters. The batteries are still performing well with zero maintenance since 2012. My plan is to do nothing until they fail and when they fail, I will just replace them. I have no idea how long they will last.

[Narallieda]

I have the Basecamp 16x. It's stored under covered parking for the winter. We get weird weather and it's safer for it there. Should I be removing the batteries for a trickle charger?

[Rolind]

We have the same situation. Same trailer and stored under cover. The first year I took the batteries out and placed on a trickle charger. They weigh a lot and it isn’t much fun lifting them out of the battery box under the sink. The second year I purchased a Renogy 100 watt panel and a Wanderer charge controller and placed the panel in the sun and plugged into the zamp port on the front of the trailer. Note well that the polarity of the Renogy panel and the zamp port are reversed. This year I changed my factory installed charge controller to a Victron MPPT 100/30 charge controller and rewired the front zamp port to run through this controller along with the rooftop solar.
Another option would be to plug the portable solar panel into the zamp port on the roof. It isn’t very easy to access, but would negate the need for another charge controller.

[Narallieda]

Originally Posted by Rolind

We have the same situation. Same trailer and stored under cover. The first year I took the batteries out and placed on a trickle charger. They weigh a lot and it isn’t much fun lifting them out of the battery box under the sink. The second year I purchased a Renogy 100 watt panel and a Wanderer charge controller and placed the panel in the sun and plugged into the zamp port on the front of the trailer. Note well that the polarity of the Renogy panel and the zamp port are reversed. This year I changed my factory installed charge controller to a Victron MPPT 100/30 charge controller and rewired the front zamp port to run through this controller along with the rooftop solar.
Another option would be to plug the portable solar panel into the zamp port on the roof. It isn’t very easy to access, but would negate the need for another charge controller.

That is a tight squeeze to get to those batteries. I'm having trouble getting the battery box open. Does it slide forward to get the lid off? Also, solar panel suitcase would have been my first option, but it is stored in a storage lot and I don't trust that the panel wouldn't just .... walk away...

I decided to order the bluetti ac200max and just bring it out there once a month to charge up. That also solves my husbands laptop charging issues. (no excuses to not camp now! HAHAHAHA)

[Rolind]

Originally Posted by Narallieda

That is a tight squeeze to get to those batteries. I'm having trouble getting the battery box open. Does it slide forward to get the lid off? Also, solar panel suitcase would have been my first option, but it is stored in a storage lot and I don't trust that the panel wouldn't just .... walk away...

I decided to order the bluetti ac200max and just bring it out there once a month to charge up. That also solves my husbands laptop charging issues. (no excuses to not camp now! HAHAHAHA)

The top of the battery box just lifts off, but there is a slot on the back side of the box that the lid fits into

[waninae39]

AGM and LA batteries can be left outside. just like your car

Lion batteries should come inside if the temp states below 0C

[uncle_bob]

Hi

Lead acid batteries (regardless of glass mat or not) freeze somewhere below -45 degrees (F or C it does not matter). "Somewhere below" may well be down around -80. Unless you live in parts of Siberia, you will not see a charged lead acid battery freeze when stored outdoors.

Lead acid batteries that are fully discharged will freeze just below 0C / 32F. You do not want to run the battery dead flat and then store it over the winter. One way or the other, the outcome will not be good.

Lead acid batteries that are in reasonable shape do not discharge much at all when in winter storage. The low average temperatures reduce the internal leakage to almost unmeasurable levels.

Simple answer for lead acid batteries: Fully charge them and then disconnect them. Leave them in the trailer. They will be fine. Hook the wires back up (or throw the full disconnect switch) and away you go in the spring. Note that the use/store switch is *not* a full disconnect switch.

Lithiums are a bit different. They will not take a charge below freezing. You aren't going to charge them in storage so that's not a really big deal. Manufacturers typically rate the to -20C / -4F. There are studies that show no freeze style damage happening until you get to the same -45 kind of temperatures. What you do with them is up to you. Mine just sit out on the trailer. Never had a problem.

In both cases the "keep it simple" solution is one that works. Doing anything more complex gets you into more possibilities of failure. Since it's not needed, why take more risk?

Bob