I have two 180 Varta Sealed FLA 12v batteries in my stable block Which are charged by a 240kw solar panel on the roof to provide lighting to the stables.

The batteries are in the feed room and we recently boxed them in with ply wood to prevent theft as they are obviously expensive. There is a Victron charge controller just above and the batteries are only going to be charging in daylight.

Question is about adequate ventilation- the box is surrounding the batteries and has a lockable flap down lid.

The only ventilation is down one side about 1 inch wide gap x 1ft where the cables feed out of ; is this enough ventilation ?

Having read about batteries am quite confused about needs now and do not want my horses to go up in smoke! thanks for your help.


We talked about charging a lead-acid car battery inside an apartment a while back:

What precautions are needed when charging a car battery in an apartment?

My answer to that question described the reasons why I thought that was a terrible idea.

In your case, you've put sealed NiCd batteries inside a moderately airtight box. While the NiCd batteries are supposed to reabsorb the hydrogen, that might or might not happen with every charge. Considering that you've put the batteries in the stable with valuable animals, I'd tend to lean towards more ventilation than less.

That said, it might be much easier than you thought: hydrogen is the lightest gas of them all. If you vented the lid, you might achieve security and safety without much hassle. Perhaps a stout wire mesh lid with a lock?

If you'd like some guidance on much more aggressive solar set-ups than the one you're describing, try looking over Appendix A in this reference. It's a little intimidating (and probably overkill), but it does provide some rules of thumb. For example, your one inch wide slit? Almost certainly too small and too low for hydrogen to easily escape.

  • Hi thanks for replying. The lid is about 2ft by 2ft 6; do you think would need to either put a grille or bore holes in the lid or replace whole lid with mesh grill? The idea of box was also to stop dirt etc gathering over them. The two batteries stand side by side on a pallet on floor, but unfotunately the builder built the sides from floor up to height just above the batteries so lid is about 1 inch above batteries. There is a pony in stable about 3ft away, the immediate area is 12x12ft inside a barn 10x7metres with top stable door openings in three other stables. – ozzie Feb 22 '15 at 11:53
  • My inclination would be to separate the two functions: put a stout metal (grounded, if possible!) mesh over the batteries for security and something like a flip down shelf some distance above that to catch dirt. That way, you can have ventilation, security and dirt prevention all at once! Obviously, it's your stable so you have to make the call. – Bob Cross Feb 22 '15 at 14:27

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