Car Battery Killed at 2 Volts Comes Back Like New with 2A12-EX

This battery was killed by being drained to 2 volts. In 2 days, with nothing but water and electricity, it was brought back like new – AND, this battery was ALREADY 6.5 years old!

The miracle charger/rejuvenator that did this is the 2.5A12-EX available here:

  • Tom Ellis

    If I convert a small pickup truck like a Ford Ranger to all electric drive using 12 lead acid batteries will you be coming out with a charger that can recharge them all at once?
    will you be coming out with a charger to recharge the lithium ion batteries
    in a Nissan leaf, Smart car, Mitsubishi Imev, Tesla, etc, ?

    Thank you for posting the video.

    • Hi Tom, we won’t have a charger for normal lithium ion batteries. For lead acid batteries, are you going to have a 12v system or are they in series for a higher voltage, which is the most common? We have an industrial charger 25A12 that is really heavy duty but of course you can only charge 12v at a time and not a string of them for higher voltage.

      • Tom Ellis

        Hi Aaron,
        Thanks for replying.
        Yes the 12 or so batteries would be in series for 144 volts.

        I’d like to have an electric vehicle system that I can
        install myself and use lead acid batteries and your type of charger
        so the batteries will last 10 -15 years. That way all the components are fairly simple and are ones I can understand and replace fairly cheaply and I won’t need to spend mega bucks on a new battery pack after several years.

        I suppose I could get 12 chargers and isolate the batteries from each other while charging but I’m hoping you folks can come up with one that can do the 12 batteries (144 Volts) at once.

        Do you think that’s coming?

        Will your chargers work with lithium iron phosphate batteries?

        Thanks for any suggestions you may offer.


        • shijimi

          Hello Tom,

          I don’t believe there is any plan to make a charger for higher than 12v, primarily because higher voltage than 24v puts too many cells in series, leading to early failure, thus eliminating any advantage of extending battery life.

          Our chargers are compatible with LiFePO4 batteries.

          I recommend you download the free Solar Secrets report and pay special attention to the section explaining how to properly connect batteries in a battery bank to avoid early battery failure.

  • Ray McMillan

    I would like to purchase the charger but I’M FROM South Africa!!!Do you ship to South Africa and what are the shipping charges?

  • henryc97232

    I have a 2A12 and I’m trying to rejuvenate a generator battery, approx. 35AH. The red light stays on for DAYS, charging never seems to finish. Voltage during charging appears to top out at 13.5V, and the resting voltage of the battery never exceeds 12.4V anymore. I have tried some deep discharges before recharging, and water level is fine (battery not sealed). Charging of this battery was fine a few months ago. Any ideas on what else I should do?

    • Hi Henry, is it the 2a12 or 2.5a12-ex? It is not uncommon for the red light to stay on for days. Can you try it on another battery that you know is good like a battery in your car? You should be able to get the green light to come on and verify the charger is fine, which is probably is. I would try that first then put it back on the 35ah battery. Is the 35ah battery flooded cell? Or is it AMG or SLA?

      • henryc97232

        Thanks for replying, Aaron! Yes, the charger’s green light comes on just fine with other known-good batteries. The battery is a flooded cell (I can add water to it). I asked the question because, even though I have rejuvenated about 10 lead-acid batteries with my 2A12, the red light has never stayed on for 4 days (and still not done) before. Why does it do that? Thanks again!

        • shijimi

          I recommend you check the battery for open or shorted cells, following the procedure in our manual available at

          If a battery has physical damage it is not able to be rejuvenated.

          Depending on the level of sulfation in the battery, it can take numerous charge-discharge cycles to reabsorb the sulfation back into the electrolyte. The procedure is covered in detail in the Battery Secrets and Battery Rejuvenation video series available at

          • henryc97232

            Thanks for replying, shijimi! In my initial post, I mention that this battery was fine just a few months ago. I will do the test you recommend, but I will be very surprised if the battery cells were damaged while sitting on the bench for no more than 3 months since the battery’s last successful 2A12 charge-up. Thanks again!

          • henryc97232

            Once the battery rested overnight, its voltage is about 10.4V. Clearly, I have caught the battery in the process of failing, since its last charge held at over 12V!

          • shijimi

            It does appear the battery has failed and you caught it in the process. Look on the bright side, you learned a valuable lesson and if you ever run into this again you will definitely know how to check it and interpret the results!

            Each of the cells should read about 2v or a little bit over. The cell with 0.4v is obviously dead and the one with 1.8v is not good either. This explains your resting voltage of 10.4v indicating one dead cell.

          • henryc97232

            Thanks, shijimi!

  • Francisco Rodriguez

    hello Aaron, I have the 2A12-ex and I was doing the rejuvenation cycles on a 700 CCA battery using the techniques on the rejuvenation videos. The first cycle was fine but when I left the charger on overnight for the second cycle the battery just woke up shorted. Why could this have happened? Could it have been the chargerĀ“s that could be defective and boiled the battery because it was quite warm during the process but I trusted the device. Or the battery just was too fragile and the device finished it.

    Thanks Aaron in advance.

    • shijimi


      There is a space at the bottom of the battery below the plates. When plate material falls off the plates it collects there. When the level gets to the point where it touches the plates causing a direct short, that is the end of the battery. The difference between a 24 month battery and a 48 month battery is the amount of space below the plates. The more space the more time before the cells short out and render the battery useless.

      When cycling a battery, if the battery is discharged too low too fast it can cause material to fall off the plates instead of being reabsorbed back into the electrolyte. This can speed up the failure of a highly sulfated battery.

      This battery could have already had a lot of plate material collected at the bottom, and discharging too deep too fast could have caused additional material to fall to the bottom, causing one or more cells to short.

      The heat definitely indicates shorted cell(s). In the future I would recommend only discharging the battery a half volt or so in steps to avoid causing plate material to fall off instead of being absorbed back into the electrolyte.

  • Aldo Bassi

    10A12 Battery Charger
    10 Amps, 12 Volts…Is this charged now available for international selling in Europe (Italy), Thanks?

    • Jeff Moe

      Not available at this time.Please visit the home page of the Tesla Chargers website for the latest status of the chargers. Any new information will be send out to the newsletter.