Equalize with xantrex sw 4204

The "weak part" of any off grid solar system is the battery bank. You do something wrong with the batteries, and you end up with a bunch of very expensive scrap lead.

Read about batteries:

http://www.windsun.com/Batteries/Battery_FAQ.htm
http://www.batteryfaq.org/
http://batteryuniversity.com/

Get/use various tools need to confirm how well your battery bank is running:

http://www.solar-electric.com/midnite-solar-battery-hydrometer.html (hydrometer if flooded cell)
http://www.sears.com/craftsman-digital-clamp-on-ammeter/p-03482369000P (DC/AC current clamp Digital Multi-Meter)

Check SG and Water levels every week until you know how your bank performs. Then check water levels every month. You should be adding water every ~2-3 months. If more often, you may be over charging. If adding water less than once every 6 months, you may be under charging.

Make sure battery cables/terminal ends are clean and protected with some sort of anti corrosive (grease, battery terminal end "paint", Vaseline, etc.).

Understand how much power the solar array+battery bank can supply (Amp*Hours or Watt*Hours per day), vs how much load you have in the cabin.

Equalizing the battery bank--If flooded cell, you should use your hydrometer to monitor the cell SG... You equalize to bring all cells up to maximum SG. Then stop. Equalization voltage would be around 30-31 volts (typically) and ~5% of of the bank's Amp*Hour capacity (example, if 200 AH battery bank then ~10 amps of EQ current). EQ may take 1 hour, or it may take 4+ hours--Depends on how out of balance the cells are (check SG every 30-60 minutes, when SG stops rising on all cells, your are done EQ, and log the SG of each cell--that is your new 100% state of charge based on SG--Rinse the hydrometer a few times with distilled water before putting away). If badly output of balance, or if the battery bank gets too hot (not over ~110F), cool back down below 95F if bank does get over heated) or continue EQ the next day.

Most people "murder" their first one or two battery banks (it happens to all of us). Most people under estimate their loads and over estimate how much energy the solar array+battery bank and reliably supply--And generally it is the battery bank that suffers.

-Bill