I've been looking to salvage batteries from work. We have lots of old UPS units that are destined for the recycle bin -

In the pile, I found some nice looking 12V batteries that would be good for this system.

So we have 4 12v 18Ah sealed led acid batteries. Looks good. I've charged them up, and they look to have 13+V with no load. Are they REALLY good? Testing will tell.