A combination of cold, work, and family events has prevented me from working on my car lately. After Kayla dinged my nice paint job with the door of our other car, I cleaned out my side of the garage and moved Silent E where she'd be safe.
After a quick 1.5A refresh charge, I figured I'd take another shot at rescuing my two leftover batteries. They'd gone bad when I had my motor disaster, as you recall. Sometimes, if you use high voltage and low current, you can get the battery back.
The first battery seemed to work overnight! It was at 13 volts the next morning. I may be able to up my range a little, or replace that one battery that's driving me nuts! I plugged the second battery in and left it overnight.
The next morning I kept waking up, wondering what the horrible smell was. I thought a cat had been incontinent right in the room. It was terrible. Eri woke up once, too; she asked if I had been farting. :-O When she mentioned it smelled like rotten eggs, a light went off: sulfur!
I rushed out to the garage to see if the battery had exploded. The smell was definitely stronger here; apparently it was leaking into the air conditioner's fan box and being carried all through the house. I opened the garage door a crack to let the stink out.
The battery looked fine, but one of the terminals was turning black. I shut off the charger and disconnected the battery. It was very warm. I decided to shove it outside.
As soon as I touched it, it vented a cloud of gas. I jumped back, but returned immediately to shove it the rest of the way out the door. Another cloud of gas, this time OUTSIDE the garage. I shut the garage door a bit to prevent any further gassing from getting in.
I opened the windows in the house to let the stink out. When the kids woke up, the smell was still there. I was afraid it would stick to everything and never leave.
The only good thing about this is that I don't need to be paranoid about overcharging and venting my batteries any more. I've listened for tiny clicking noises that might indicate a battery was being overcharged. I've questioned every slight odor in the car.
Having experienced the stink, I can definitively say that I've never vented a battery. The regulators are doing their job!