Posted By: cudaboy
Dead Optima battery - 06/02/12 05:21 PM
I have a red top Optima that I can't get to charge. My regular battery charger will try to charge it, but as soon as I remove it, I read 4.5 volts at the terminals. I also tried a battery tender specifically for AGM batteries, and it won't get it over 5 volts. Is there a way to revive them, or is it junk?
Dennis
Posted By: Pacnorthcuda
Re: Dead Optima battery - 06/02/12 05:38 PM
The next thing to try is to grab another battery and hook it up in parallel. You can also use something like a 12volt light bulb (you need a LOAD to put on the charger so it will provide output).
THe internal resistance of the Optima is too high, in its current (NPI) state of charge.
Make sense?
Posted By: GTX70sixpack
Re: Dead Optima battery - 06/02/12 05:45 PM
My 2 Optimas are 8 yrs old or older, are used in cars I move once every year or 2. They are normally completly dead and a night on the trickle charger brings them up. I just brought both of them back to life 2 weeks ago, using one of them in my camper because the less than a yr old deep cycle lead/acid will not charge at all. I have never had one not charge yet.
Posted By: cudaboy
Re: Dead Optima battery - 06/02/12 08:42 PM
I read about the parallel thing, but I don't think I need to do that. My charger is putting out 13.5 volts, the battery is just not charging. From what I understand, the parallel way is if the charger won't come on at all because the voltage is too low.
Dennis
Posted By: DrCharles
Re: Dead Optima battery - 06/02/12 09:05 PM
I've read that another technique is to apply a high DC voltage across the battery (50-100 volts) with a suitable current-limiting resistor, and then wait. The sulfation may break down under the higher voltage. Then use a normal charger.
Some batteries just aren't salvageable though.
How long did you leave the Optima hooked up to the charger? Mine took an hour or so before it started pulling current, I think...
Posted By: pishta
Re: Dead Optima battery - 06/02/12 09:06 PM
Old mechanic told me that every time you discharge a battery to 0, you kill 10% of its ability to recharge. So a 600A battery will only be about 540, then 484, then 436..so on. If you can get a camcorder or laptop batery to completely discharge (you cant, it usually turns itself off before it gets that low for protection) you will permanently damage it. But those optima batteries are supposed to be very good, nice score.
Posted By: cudaboy
Re: Dead Optima battery - 06/02/12 09:09 PM
I had the battery tender hooked up for over a week, no change. The regular charger I had hooked up for a full day, the guage showed it was charging, but the battery voltage drops when I unhook the charger. I think it's dead.
Dennis
Posted By: DrCharles
Re: Dead Optima battery - 06/02/12 09:16 PM
Unfortunately I think you're probably right... but how much current was it drawing while on the regular charger? and what was the terminal voltage while charging?
Posted By: DrCharles
Re: Dead Optima battery - 06/03/12 12:03 AM
Try it on a large fast-charger (at 15.5 volts) for an hour... if it still doesn't come back at all, scrap it. Those batteries are good, but expensive, so it's worth a little effort
Posted By: 70Cuda383
Re: Dead Optima battery - 06/03/12 12:11 AM
Remember, voltage is only a difference in electrical charge, and is not an indication of electrical flow.
A reading of 13-15 volts does not mean you are actually feeding any amps into the battery
Now, this talk of permanently draining a battery killing it, does that only apply to lead/acid car batteries? I know lithium ions are new tech, but I thought the NiMH Batteries would develop a memory where short cycling it by not draining fully or not charging fully, would diminish its capability