cisterns

Occasional reports attribute damage to humidity but it's hard to believe. The usual culprits are heat and overcharge

https://www.google.ca/#q=high+humidity+runs+down+battery

Why does anything you're asking about have to do with the cistern? I don't get it.

(Assuming there is nothing draining the battery due to a miswire or short or overcharging and/or regular charge cycle) ...

FYI, salt (plus humidity) in the air in tropical climates is quite corrosive. Ask around and you'll find neighbors relating such stories as the norm. Same in PR and in so. FL nr the shore..(within 10 miles).

The cistern is located under my garage. The relationship is that others in my neighborhood have golf carts parked in their garages and they don't have cisterns and they don't have the same problem I have with my batteries. I am trying to figure out if there is a connection.

Thank you for responding. I have neighbors that deal with the same heat and humidity but don't have the same problem. The common denominator is the cistern. I keep my batteries filled with water and on a charger.

firstly, I'd check out and see if the battery charger is overcharging.

Secondly, I'd run a dehumidifier in the garage and see if that made a difference. Though, admittedly it could tun into some added electric bill.

Lastly, I might see about putting down some chemical water sealer on the floor of the garage to make a better vapor barrier on the floor.

Once your batteris are charged (AND theres no trickle drainage from some internal wiring problems on your vehicles) they should HOLD a charge all winter. Is your cistern overfilling and draining into the sub bedding? That's really the only way that Id see a modern (stressed concrete) cistern from affecting the garage humidity.
Anyway, Id still keep a ceiling vent and dehumidifier in there to keep you from getting a mold problem down the road.

I had a golf cart at our place in MAine and I installed a breaker switch on the battery bank (I hd 4 batteries) so that , when we went home there was no possible draining from the golf cart.

The humidity is probably forming a conductive layer atop the batteries. Clean them very well and use Vaseline Petroleum jelly aroind the terminals and straps if you have them.

It's been a while, Mechsmith. Good to see you back.