Our First Solar Battery Problem

Two weeks ago we helped out a friend with his solar battery array. His battery readings had started going a bit wonky, then a couple nights later one of the batteries exploded. After analyzing the problem, he temporarily disconnected one third of the battery bank and stopped using electricity at night as a bandaid repair until he could purchase new batteries.  We lent a hand installing the new batteries and wiring the new battery bank.

Hubby and I had felt fairly smug that our batteries were doing so good, so we thought. Our group were two years older than our friend's and still charging and discharging fine, so we thought. We cared for them attentively, giving them a thorough going over monthly, keeping them in the prime, so we thought. Well, after 3 "so we thought's" you must know by now that we were clueless. A few days ago we started getting wonky readings on the batteries. Oh brother. We borrowed the new hydrometer our friend had just purchased and were really surprised what it told us about our own batteries. The side of the battery bank that we suspected was aging the fastest actually was in decent shape, though not great by any means. Right on the lower readings in the "good" section. The other side was in horrible shape with numerous cells practically dead or real dead. Oh my, oh my, oh my.
The bad cells were dragging down the whole system.

I guess we wouldn't have noticed the aging if we weren't in a sunless weather pattern right now. We've had very, very little sun for the past three weeks. We've had to run the generator a few evenings to top up the batteries. But suddenly that batteries weren't holding the charge. 

For more than a year we've been talking about moving the dc appliances to their own solar panels/batteries, but we never got around to really thinking it out. It wasn't a pressing issue. But now we have the opportunity to do the job, since we are looking at a major battery replacement job. So over the next two days hubby will be planning out the strategy. We already have the solar panels. We will need a simple charge controller. Four of the decent batteries in our current bank should be usable for the task, as starters. 

As we work our way through this job, I'll show you what we are doing. It will be a learning experience for us too.