Can you revive a dead car battery by inverting its polarity?

If your having problems with battery thieves, that is the battery to leave for them to steal lol.

I've dealt with a reconditioning shop. They would slowly discharge to zero, reverse charge and actually use a high voltage or amps to boil the acid. Then drain rinse and refill, then slow charge. Recheck and sell as cheap reconditioned. Most of the time many batteries go dead from sulfur buildup. Reversing the charge knocks off the sulfur. I used to have a reconditioning charger that did the same thing. Took about 2 days to complete. Worked very well, even on some AGM's

Fully charge it in reverse polarity and leave it outside for the battery thieves. They’ll be “shocked” by what happens when they install it in their car. 😂

Had a battery that was 11 years old and died. changed polarity back and forth twice, and it is stil working fine after 5 more years.

That starter is impressive

"Where's that smoke coming from?" Starter: "Where TF you think?!?"

Someone give the guy that built that starter a raise!!!

The most surprising thing is how the starter motor held up and how the flimsy stock cables didn't melt

There is a german saying: "Everyone says it does not work but never tried it. Than there came one who did not know and just did it"

Now recharge to the correct polarity and retest.

I accidentally hooked up leads wrong on a completely dead battery years ago. It charged up completely but in reverse. I ran it down dead again & recharged it hooked leads correctly. It worked.

Wow. Lada starters are amazing!!

Part 2? Drain it back down and see if the polarity can be reversed back to original polarity?

I'm impressed not about the battery but about the Starter motor. That starter motor must have heated up to over 200°. Before it quit working.

We did a similar test when I was in high-school we took 5 sulfated batteries drew them down similar to what you did and hooked a battery charger up backwards momentarily (the charger was one that you could adjust the amperage manually) then trickle charged them @2 amps, 4 out of the 5 performed as they were supposed to, with the correct polarity, it was explained that the reverse polarity removed the Sulphur from the plates

This won't be the case for all failed batteries as they can fail in many different ways but hey it's worth a try, even if it only gets you to the next pay check it's worth trying. This channel never fails to answer questions I never asked (but maybe should have)

Fascinating about the reversing battery polarity! But I find it more impressive that that starter motor didn't fail after all that!

Because the last cell which is tied to the cathode is typically the cell that's gone bad from corrosion, reversing the polarity and the pulsating D.C. from the alternator can break up the tendrils, and potentially relocate some of that debris into the other cells, so you lower the cathode cell's resistance enough to get it to hold some effective voltage. Cleaning out the old cell with a potent acid and all the cells really, then flushing it, refilling it and lastly, using a pulsating D.C. charger can restore a dead battery completely. When people hit them with a really hot D.C. such as a welder as some have mentioned, it can burn through some of the high resistance corrosion and get it functional again. With my background in engineering though, if you can't replace the cathode cell but you can effectively clean it out, this is the first and most crucial first step to restoring the battery and it being reliable. I've seen people use the welders and other high voltage sources of pulsating D.C. to get the battery back in good working order again, but even if it charges to capacitance I think it's highly likely that the corrosion debris is going to return to the cathode cell and before too long, it's going to fail again. A lot of businesses that rebuild batteries are simply replacing cells and, in many cases, the cathode cell will be the only one in dire enough shape to need extensive work whether it's a good cleaning or replacement. I did a motorcycle battery last year and the cathode cell was abysmal, but the rest still in very good shape. The amount of gunk I stripped off and poured out after repeatedly treating it with acid was ridiculous, but afterward, the cell looked to be in very good shape again.

Didn't expect that to actually work.

I have been sitting on 6 dead batteries that I have collected over the years... I even tried reconditioning them. This actually works?!?!?! This is an off grid game changer.