Questions about battery storage over the winter

[suburbancowboy]

As many of you recall last fall and this spring I built a portable solar power station for the cabin.   I will be going up to the cabin for the final time this year in a couple of weeks.  I will be bringing the ATV's home and putting the trailer in the bunk house which has one south facing window.  My question for all of you is to whether I should pull the batteries out of the trailer and bring them home or leave them in and let the panels keep them charged.  Bringing them home I have to worry about them going dead.  Leaving them up there I am afraid the controllers will wear out sooner.

Thoughts???

[MountainDon]

Here's my drill...
1. make sure the battery fluid is over the plates.
2. fully charge the batteries
3. equalize the batteries if that has not been done in several months
4. recheck the fluid level

I leave the charge side of the system sitting there in the normal working state. Our charge controller is user programmable so I reduce the time spent in absorb charge from its normal setting. Every day when the sun rises the charge controller starts with a bulk charge, switches to absorb and then goes to float. The batteries used very little water over the winter (November to April). When we do snowshoe up in the winter I might increase the absorb time if we have used the batteries to any appreciable amount or if we stay for more than just a couple of days.

The inverter is left off, the disconnect between it and the batteries is pulled.

The main DC cabin accessory circuit breaker is pulled to ensure there are no loads on the system other than the very small standby power the charge controller consumes while waiting for the sun to return.

The way I look at leaving the system as described is that there are plenty of people who use their system every day for years. Most do not have equipment problems. In our case hauling the batteries out is too big a job and would mean we'd have no power, other than the generator, when we snowshoe in.

So, as long as their would be some sun coming through the window it would likely be sufficient to maintain the battery charge.

Oh, I also has two small panels (22 watts or so) connected to the RV batteries through a cheap controller. The panels are even partially shaded at times. They have kept the RV batteries charged throughout a couple winters.

[Phssthpok]

Downhill neighbor has four T-105's in an airstream trailer at ~6000ft in the mountains. Last fall he set up one (1) of the Harbor Freight 15w panels with a Morningstar Sunguard controller and threw the main switch on the system to the "off" position.

Around here we don't count it 'cold' till it get to the teens below. The batteries weathered the winter just fine.