winter charging

[Jerry Pierson]

Don't go up to the cabin during the winter and want to keep the batteries fully charged.

Panels are on the roof of the bunky and get 2-3' of snow on them.
Thinking of installing a 50w panel on the bunky wall where it won't get snow accumulation.

Do I need a charge controller? Do I turn off the roof panels and just trickle charge using the 50w?

[Rob Beckers]

Hi Jerry,

Yes, definitely a charge controller! While unlikely, there could be a sunny week in winter where that panel keeps charging and charging, without a controller, and cause quite a bit of water loss in the batteries. PWM controllers are cheap enough not to have to run this risk (keep in mind that 50W at 12V is still 4 Amp max!).

In a larger context, you don't really have to charge your batteries over the winter if there are no loads. What I tell people, and that has worked well over the years, is to make sure the batteries have a full 100% charge, then disconnect all the loads (inverter etc.). If the panels are likely to see sun a few times during the winter then leave the charge controller connected. If that is not likely, then disconnect everything and just let the batteries sit. They are happy to sit at full charge for 4 months, nothing happens to them, in particular at the low(er) temperatures of winter (slows down the chemistry).

-RoB-

[Bob Levac]

Hi Jerry,

In a larger context, you don't really have to charge your batteries over the winter if there are no loads. What I tell people, and that has worked well over the years, is to make sure the batteries have a full 100% charge, then disconnect all the loads (inverter etc.).-

Hi Rob,

I'm new to the forum so this thread is a bit old but I was wondering if keeping your battery configuration with no load is OK for winter storage or should you disconnect all of the series/parallel wiring as well?

Bob

[Rob Beckers]

Hi Bob,

If your batteries are in decent shape they should be fine with the series/parallel wiring connected over the winter.

The problem is when you have one (or more) bad cells; they will self-discharge quickly and in case of parallel strings pull the Voltage of the other string with it. In that case it would be better to disconnect the wires that connect the strings in parallel (series is no problem, there's no current going to flow through there if they are just single strings).

Hope this helps!

-RoB-

[Bob Levac]

Hi Bob,

If your batteries are in decent shape they should be fine with the series/parallel wiring connected over the winter.

The problem is when you have one (or more) bad cells; they will self-discharge quickly and in case of parallel strings pull the Voltage of the other string with it. In that case it would be better to disconnect the wires that connect the strings in parallel (series is no problem, there's no current going to flow through there if they are just single strings).

Hope this helps!

-RoB-

It does thanks!