The Stovebolt Site Forums The Shop Area The Electrical Bay Battery overcharging after electrolysis

Yeah, weird title. I was using electrolysis to de-rust some parts from another project and I used my truck battery (12 volt) in the process. The battery gets placed between a battery charger and the electrolysis tank because (at least as I understand it) the new chargers need to sense voltage or they don't work. So you connect the charger to the battery and the battery to the part you're trying to de-rust.
Anyway, after I was done, I put the battery back in my truck and it cranked a few times and died. I jump started it and it was fine but the ammeter pegs all the way to the right when I rev the engine. At idle, it's about halfway between the middle and the C. I drove about 26 miles on the highway and the needle stayed pegged to the right the whole way. Still doing it today, too. The voltage on the battery with the engine off reads 12.3 volts. There is no acid boiling over, no weird smells, nothing obviously out of line. Would it take this long for the battery to get recharged? It starts right up without any problems. But it just takes a little pressure on the gas to get the needle pegged all the way to the right. Any ideas what's happening?

Use a hydrometer to check the state of charge of the battery after doing a "slow charge" of around 10-15 amps at least overnight. The specific gravity of all the cells should be approximately equal and somewhere in the range of 1.265-1.275. A specific gravity reading below 1.250 indicates the need for more recharging, and if any cell shows a specific gravity reading that is 25 points or more below the rest of the cells, replace the battery.

There is no other effective way to tell if the battery is taking a full charge other than monitoring the acid concentration. The charging system voltage with the engine running at a fast idle against a fully charged battery should be around 14.5-14.7 volts with a charging current going into the battery below 15 amps.
Jerry

Thanks, Jerry. I will give that a try.

Putting the battery on the charger overnight solved this problem.
Thanks, Jerry. The hydrometer indicated a very low charge in all cells prior to charging. It was much higher after a night hooked up to the charger. I put the battery back in the truck and everything worked normally. I am curious to know how long it would have taken to charge the battery with the generator alone, or if it would have worked at all.

It takes quite a while to get the battery all the way up. I ran mine down some and it took several hours of driving. The charge rate drops off as it makes progress as it is very gentle on the battery.