So I am expanding my solar setup and am finally getting my battery bank outbid the attic. I want it in a conditioned space and the only conditioned space is in the house somewhere. Before you get all freaked out by the aspect of a battery bank in the house let me give you some details and then I would love your opinions. Ok the bank itself is four 6 volt deep cycles in series for a total of 24 volts, 860Ah. They will be receiving 940 watts from four 235 watt panels. I will have fuses in line with each battery cable as well as fuses in the disconnect on the AC side as well. Now where I want to put all this is in a bedroom closet. The closet backs up the back of shower plumbing so there is a little removable panel in that wall and when that panel is taken out there is openings to the crawl space so what I want to do is cut in and mount a little computer fan to pull air up under the door, over the batteries and disperse it into the crawlspace to prevent any hydrogen buildup. What do you think? And thanks!
I suggest two fans for redundancy. If one fails, you'll still have air flow to prevent hydrogen build up. Be sure to use brushless fans; the last thing you want is a spark or electrical arc in the exhaust channel.
The plan seems solid enough to me, allowing for the fact you have to vent upwards as Eric pointed out.
You might want to inquire about how this might affect your insurance. In the case of a fire *by any cause* you want protection. The batteries wouldn't be something you could hide after the fact, so check to ensure they don't invalidate your coverage.
I suspect it would cause issues, yes. That's why I bring it up. Your solution seems functional; I believe it would work. Still, I would consider the possibility of insurance trouble when finalizing your decision. It may not matter, or it may. It would matter to me.
Having the system up to nec and local code requirements will go a long way toward making them comfortable. Never know what they will agree to or not accept without conditions until you ask.
If you can ventilate with convection then you will not need fans. Fans are a good thing if the path is not straight and for ventilating on a voltage set point control accessory device or program in your charge control for saving thermal energy in the home and electric power in the system.