Desulfator in an altoids tin


If you’ve ever let a car sit for a period of time and returned to find that the battery was mysteriously “dead”, you were probably experiencing a sulfate crystal build up. Often, people just buy a new battery and plop it in, but that isn’t absolutely necessary. [Kmpres] takes us through the process of building a desulfator. A desulfator works by putting high voltage pulses into the battery forcing the sulfate crystals to dissolve back into the electrolyte. From what [Kmpres] says, you can find “bad” batteries in all kinds of places, use the desulfator on them and have perfectly fine batteries when you’re done. You may recall doing something similar with a disposable camera.

24 thoughts on “Desulfator in an altoids tin

  1. haha at first glance i read “defibrillator in an altoids tin”. got excited for a second there :) still cool, i hadn’t heard about sulfate buildup before.

  2. its not a fun thing to deal with(sulfate build-up that is)building some thing to fix that problem now thats fun lol

  3. here in germany they have quite strikt rules what can go in a car and what not. If you put DIY in it your insurance company can deny payments in case of an accident. So I went for a built one in this case, as in addition it features an undervoltage protection, making sure the battery won’t die if I don’t use my car (which can be month…)

  4. In Venezuela, they have special lemons, all they do is stick two leads in the lemon, say a few magic words, and bam! They have a new battery. Guess you don’t travel much barqer.

  5. So this circuit is draining battery to desulfate it ? The problem with sulfate build-up is, that actually breaks the internal structure, since the sulfate has a higher volume. The battery can be repaired to a certain extent, but never completely. It may exhibit higher self-discharge current.

  6. A longer look revealed a note:
    “Since the circuit draws battery power, a trickle charger should be connected to the battery while the circuit is in use”

  7. I think the process of desulphation is essentially to pass a very large current through the battery (shorting it essentially) for a split second, while charging it – a bit like the idea of burp charging of nicads and nimhs. As demo said, it’ll only patch a dead battery and make it work for a bit longer, often the suphation has damaged the battery, and regardless the battery is more prone to re-sulphation. Good if you’re penny pinching, but you can buy a 3 year guarantee Bosch battery for £35, hardly worth it. Still, good project, good demonstrator.

  8. Is there any proof that the high frequencies offered on these things are any better than the 120Hz offered by a lamp cord and a full-bridge rectifier minus capacitors?

  9. Desulfators have been around since 2000. If you read the instructable and check out the links in it, you’ll see that they are used to restore not just car batteries, but also large banks of batteries in PV banks, electric golf carts, wheelchairs and many other applications. It’s not a patch and it doesn’t result in a temporarily improved but degraded battery. It instead, reverses the process of sulfation returning the lead sulphate to the electrolyte, from whence it came. With the lead sulfate off the plates the acid can contact the lead again and the battery can produce electricity up to its normal capacity. Desulfators are especially useful for owners of RVs and off-grid PV systems (if sufficiently scaled up in size) because they can get 10 years or more of life out of their very expensive battery banks instead of having to replace them every few years due to sulfation buildup. Again, the process simply returns the lead sulfate to the electolyte, from whence it came, so there’s no buildup inside the battery after the process is complete. And it keeps your battery out of the local landfill where it pollutes the ground and water. For me, that’s worth the small price of this circuit alone.

  10. I don’t recommend using rectified 120V AC on a car battery due to the potentially lethal voltages involved, not to mention the potential for sparks around gasoline and hydrogen gas. Frankly, you’d have to be nuts to attempt it when this circuit will do the job safely and can be left on indefinately as long as a trickle charger is connected with it. It also uses only the power in your battery so you don’t have to pay for electricity to feed it power so your battery can produce more power. However, high voltage desulfators are used on large banks of batteries. See the instructable for a link on this.

  11. dear sir
    i want to purchase a desulfator 12v please let me know he price with dhl charges iam staying in india hyderabad give me the payment terms and how fast you can send

  12. Hi, I’ve a PV system using a battery bank of 20 x 12v 150AH batteries connected in series. Could I use one of these desulfators or would I require twenty to clean all the batteries? You mention that it’s possible to build a desulfator that’s capable of handling the whole battery bank at one time, but where would I find information about such a project? Any help would be greatly appreciated. Thanks!

  13. No need for separate desulfators for each battery. The Intro page of the instructible has a link to a high power version that can desulfate a whole bank of batteries. The webpage is old but it’ll give you an idea of what to expect. Essentially, it’s just larger coils, diodes, FETs, higher voltage caps, and voltage regulation for the chip. Check out the link and the Home Power websites for more info.

  14. In Venezuela, they have special lemons, most of them grown by Miss World and Universe. Most batteries are sulpahted by those lemons.

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