Venting the battery bank.
From a safety aspect I wanted the battery bank external from my cabin for a couple of reasons. One, we didn't want the hydrogen venting into the cabin from the battery bank when charging. Two, we need the space. What I learned is that during the cold months you can have the batteries in the cold. The downside is that I was only using about 7% of the available amps, but voltage wise when the state of charge was showing 95% full, the voltage was around 48.8 volts. On a 48 volt system that is about a 40% discharge. In cold temps this becomes a freezing issue. I should clarify that these batteries are your typical lead acid for solar. (There are salt water batteries that are made for cold enviornments.) Lesson learned!
The bottom line we moved the batteries inside, and keep the cabin warm. I have left them fully charged, outside in the cold (about 5 degrees Fahrenheit) and came back three weeks later to find that they only had dropped 3 tenths of one volt. (51.1 to 50.8 volts) These batteries had no loads as all breakers were in the off position. Another lesson learned. You can keep them outside.
The main reason I move the batteries inside was due to charging. In the near zero temps the charging amps were very low, and the voltage was barely above a full charge status. I think it was charging like at 54 volts with 3 amps. Its a good thing that I had a battery monitoring kit installed with my Magnum 4448, as it regulates that charge so your batteries won't crack or explode. As soon as I saw this, the batteries were moved. Another lesson learned in the solar power arena.
With this I'm throwing up some pictures of how I installed my vent and fan to move the hydrogen outside.