Tricks to bring back a 'dead' battery?

[Carl2500]

Here's a trick I've used a couple times to bring back a battery previously thought to not be able to be charged.

Most battery chargers in the last 10 years have a safety feature that will make it so it will not charge a battery that has a voltage under about 10 volts. If you take a pair of jumper cables and connect a good battery to the bad battery in parallel (+ to +, - to -) and then connect the charger to the good battery, it will trick the charger into seeing a good voltage, and charge both batteries. Once the bad battery has a voltage above 10 volts the battery charger will charge it properly.

I have also heard if you have a recently discharged battery, you may be able to get one last start (to get you to the nearest auto store to buy a battery) by adding half an aspirin to each cell. This has to do with the chemical properties of the aspirin combining with the sulfuric acid of the battery.

So ya guys know of any other tricks that may help an old battery?

 

[Balzer]

Just as you described is about the only way to recover dead optimas, With a 2 amp or less trickle charge and about 24 hours. I Have herd a lot of negitive opinions about optima batteries in the last few years but I have a theory that its the newer chargers as you described "not seeing" a severly discharged optima. I too felt their quality had diminished until one day I read about newer chargers not charging if the batt was below 10V. It then dawned on me that I had to replace my old trickle charger after someone had left it sitting on their tire and drove away.
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Recently I bought a new optima yellow top for my 94 chevy project. While the truck was being worked on the battery got used to start several other vehicles and test various electrical components as well as being left on during the work. Long story short the batt went dead and my brother and his friends attempted to charge it without success. They figured the yellow top was ruined. I stuck the jump cables on a good batt and the yellow top put it on 2 amp charge and left it overnight. The next day both batterys had a full charge and have been fine since.
I have since discovered that this method is actually optimas prefered way of charging all their batteries regaurdless of the discharged voltage be it 11 volts or 1 volt.
Good thread!

 

[Carl2500]

Also you may have some luck by using a charger with a 'desulfator' circuit, which is what battery stores and scrap yards use to remove sulfur buildup on the plates, to recondition old batteries.

 

[Buddha.]

Im reviving a dead thread rather than starting another. I left the lights on overnight on my truck. In the morning battery voltage was 7.8!. I put the trick charger on it but im wondering if it'll recover or do I have a bad cell
The battery is only six months old and still under warranty.

 

[jonyjoe101]

leaving the lights on one time shouldn't kill a 6 months old battery.
About 3 years ago I bought a use battery and several month later left the lights on in my van all night long. In the morning the battery was completely dead. I have a 240 watt panel on my roof and was able to connect the mppt controller to the start battery, 3 hours later I was able to crank over the engine.
Since that time I left the lights on another 3 or 4 times this time by accidently hitting the light switch when getting out of the van. I made a special cover over the switches, it hasnt happen anymore.
If you can't recover your battery at least its still under warranty. But I dont think 1 or 2 discharges will kill it, I think normal flooded start batteries can handle about 10 complete discharges before they lose capacity. AGM's can handle even more abuse since some are deep cycle capable.
I thought I had damaged my battery with all the abuse but 3 years later its still running like a champ.

 

[4x4junkie]

×2. I think chances are pretty good a six month old battery will recover, though maybe with having lost a little bit of it's capacity (might not be enough to really notice).

 

[Ducky's Dad]

Some of the new high tech chargers will recover batteries that are under 2.5 volts. I think my new Odyssey charger has that capability, but I haven't had to use that feature yet.

 

[Scott Brady]

I have had good luck with the Ctek chargers

 

[Martinjmpr]

Here's a trick I've used a couple times to bring back a battery previously thought to not be able to be charged.

Most battery chargers in the last 10 years have a safety feature that will make it so it will not charge a battery that has a voltage under about 10 volts. If you take a pair of jumper cables and connect a good battery to the bad battery in parallel (+ to +, - to -) and then connect the charger to the good battery, it will trick the charger into seeing a good voltage, and charge both batteries. Once the bad battery has a voltage above 10 volts the battery charger will charge it properly.

That's exactly how I brought the Optima red top on my wife's YJ back to life in 2014 (a dead alternator on the Jeep killed it.) Now the jeep has a new alternator and I keep it on a battery tender too. Starts up just fine even after months of sitting.