[RE-wrenches] Wintertime battery maintenance charge rate?

Dan Fink danbob at hughes.net
Tue Jul 13 13:55:41 PDT 2010


Hello esteemed Wrenches;

I'm currently at a remote job site in far Northern BC, float plane and 
helicopter access only. My system install was a success, as I am using 
satellite internet to ping the list here!

There is a main lodge, and a remote camp, and neither are occupied from 
November thru May. The remote camp gets ZERO sunlight for 3 months of 
the year, while the main lodge is on a lake and gets some sun each 
month. Both PV arrays must be stowed indoors for the winter, as they are 
on ground racks and the Grizzly bears and moose will rip them to shreds 
when nobody is at the camps during winter, and snowdrifts can be 10 feet 
deep or more.

My plan is to move the small battery bank box (2 Trojan T-105s in a 
cooler) to the Lake by helicopter each  fall, parallel it with the 
batteries there all thru the main DC fuse (6 Trojan T-105s wired for 
12v), and run a small winter maintenance PV panel into all for the 
winter. Total of 880 amp-hours capacity.

My question is, how much winter charging is needed to keep the batteries 
charged and prevent freezing? We have an existing Unisolar roll-up panel 
on site that is showing 24 watts on my meter, and can be mounted on a  
tall pole. Is that enough? Temps can reach 40 below F.

Your input is appreciated!
DAN FINK
Buckville Energy Consulting LLC



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