The reliability of the battery is a critical point. The lead-acid may still be a potential candidate. Reliable ones may be found in forklift trucks and electric power plant emergency systems.
Offered by Olli.
Deep cycle lead acid storage batteries are the batteries of choice for over 90% of the off-grid homes. ... Out of 15 nicad set only 2 of them were not swapped out for lead acids within two years. Lead acids work very well, especially considering their price advantage over other type of batteries. They need to be kept warm or otherwise compensated for cold conditions, need to be kept at a good state of charge (as do all batteries), and they should be vented to the outdoors.
If you recall back in the old days when lead acid batteries first came out, they were housed in asphalt cases. They were also rebuilt. Later they were recycled. Then, they became disposable. Why did it go this way? Well, more money for the manufacture, I would guess. The how to do this rebuilding is still out there. It wasn't that long ago. We need to find it and polish it up a bit and stock up on acid, lead, separators, posts, etc. Possibly we can saw the tops off the old ones and use the same cases when rebuilding them.
Offered by Mike.
The best maintenance is to recharge them fully periodically. As for rebuilding, keep a supply of EDTA to recover heavily sulfated batteries. As for physically rebuilding, batteries with thick plates (a property of deep discharge batteries) can be scrubbed to eliminate the sulfate buildup but you'll need battery (sulfuric) acid when you recharge. Very messy, very dangerous, not recommended. The difference in deep cell batteries has more to do with size; from golf cart batteries to submarine batteries and many in between. Pick a size according to your budget, but don't mix and match different sizes together. Also, ones of the same age are best together. One that is failing will pull power away from the good ones.
Offered by Steve.