Battery Desulfator


Hack a Day favorite [Mikey Sklar] is back with a new project. Mini-D is a battery desulfator. If a 12V lead-acid battery sits with a voltage below 12.3V, sulfur crystals will begin to form on the lead plates. This crystal growth increases the internal resistance and eventually makes the battery unusable. A battery desulfator sends high frequency pulses through the battery to create a resonance that will break up the crystals. On a 60lb automotive battery, it will take approximately three weeks to completely desulfate. You can find schematics plus a dozen lines of code for the ATmega169 on his site. Embedded below is a video where he explains the device and other techniques like load testing.


30 thoughts on “Battery Desulfator

  1. bah why use such toys when if you know what you are doing you can do this with such things as a dead mans cord or even a welder if you are really really good.

    oh yeah going that route can be very dangerous and i do not suggest anyone try it, but it does work

  2. @thomas

    Wrong. This is for batteries with high internal resistance. That doesn’t imply that there isn’t potential energy sitting there ready to be unleashed as soon as conditions allow…

  3. @Andrew Pollack and @dreath: Personally, after all the recent stories of batteries bursting into flames, I always assume that a battery is capable of, at least, splitting and spraying it’s electrolytes around. The best bet might be to put the battery in a metal can with a loose lid (garbage can?) and make sure it’s in a reasonably ventilated area over the three week period you’re doing this. The metal should stop any flying electrolyte/battery components and by keeping the lid loose, and locating the can in a ventilated area, you should be able to deal with any fume build-up safely.

  4. Actually battery maintenance is quite dangerous. sulfuric acid, which is where the sulfur crystals come from, is highly corrosive. You noticed he was in an open area, wearing gloves. Ideally, shorts and a t-shirt are not good clothing to wear when doing this, as a splatter or spill is likely to hit unprotected skin. Eye goggles at the very least, I would suggest splash shields instead. I never had a problem with discharge, but if you have ever seen a capacitor spot weld a motherboard then you should treat these things like that. They are capacitors in a literal sense. More danger from the acid though.

  5. Surely, three weeks of this thing chugging away, eating electricity, would negate any savings. Buying a new battery must be cheaper, what is its power consumption? Not to mention the $55 to ship it”!

  6. Define “high frequency”? I do pretty well with my homemade desulfator, which consists of full-bridge rectifier spitting out 120Hz half-wave, some resistors, and a regulator to bring the pulsing DC down to 14 volts. I’ve never seen a reputable citation saying that frequencies higher than that do anything worthwhile.

  7. Is there any way that this trivial task could be done with MIPS r10000 CPU or at least Pentium 4?

    no, seriously, I want to know if someone ever used an cray supercomputer as a doorbell, or RFID tag?

    I seen all kind of crap done by mcu’s, but this beats all of them.

  8. Hey is it possible that we attach the desulfator permenantly to the lead acid battery????

    like with the UPS,auto battery etc etc??????
    will it be good for the battery to attach it for along??????will it keep the battery fresh all the time?????or what???m bit confuse in it!bhaaaaaa

  9. As Eliot Phillips works great im really impressed……..Well i need all of your suggestions about my above post…….as im a Manufacture of Lead Acid Battery and im thinking to attach the lead acid battery permenantly during manufacturing battery………and sell it …what you people says about it??????


  10. I WORKED AT A Autozone years ago while finishing my EE.

    People used to bring in HOT car batteries spitting acid sides all bulged out and plunk them down on the counter expecting me to test them or something.

    I remember one was literally smoking and would shake all by itself, I left it on the counter for hours and avoided going anywhere near it.

  11. If these devices are so marvellous, why hasnt the industry taken it more seriously (I dont mean battery manufacturers who surely dont want you prolonging battery life), I mean Solar power Cos, Industrial UPS suppliers, electric vehicle mfgs etc ie serious players. Its in all of their interests to have a so called device that can monitor battery performance and extend battery life/capacity.

    Big silence out there – very suspicious

    So much of what I have seen so far has been put forward by persons with little or no formal technical or scientifical training – as evidenced by the way they explain themselves

    Ive never seen any properly conducted trials with measurment data, graphs etc.

    From an electrical aspect I cant see how the device powers itself from the battery then reinjects back into the babttery. Does it switch from taking power from the battery, storing it in a capacitor/ or choke, then switch over to reinject the energy spike back into the battery?

    Once again the protagonists have been very poor at technical correctness, talking of resonance, high frequency, 1kHz square waves etc, all very amateurish

    1. The industry has taken is seriously. I found this thread when searching for “battery desulfators”. I’ve already run into two companies that make these and know of a third that has been making them for years. It’s just a niche product that manufacturers would rather you not know about. But this economy has people getting efficient, and saving money is a big part of that.

  12. There’s a proven way to desulphate unshorted lead acid batteries.
    Get a high current welding machine starting at 50A, connecting to a high current diode and connect to the poles positive to positive on the battery, negative to negative. connect for few seconds, and short the battery poles with a thick wire until voltage drops. this is one cycle, you have to do it for at least 8 cycles. The success display is when you shock the batteries with welding machine, the sparks get stronger, showing that the current flowing through a battery is getting higher.

    Precaution, flood the battery until its recommended level, open the caps to allow safe gassing.

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