wow this rules. seriously something useful on this site? haha that rules my hats off to you hackaday

Posted at 8:28 pm on Feb 7th, 2009 by Peep

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.

Posted at 10:04 pm on Feb 7th, 2009 by andrew

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

Posted at 2:20 am on Feb 8th, 2009 by jiggy-wiggy-piggy

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…)

Posted at 2:43 am on Feb 8th, 2009 by ragnar

Wow, here in Venezuela, we just rub the battery contacts with some lemon and voila! No more sulfate.

Posted at 4:23 am on Feb 8th, 2009 by Manuel

this build is to remove sulfate crystals inside the battery, not buildup on the battery posts..

Posted at 5:30 am on Feb 8th, 2009 by Barqer

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.

Posted at 6:42 am on Feb 8th, 2009 by spadefinger

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.

Posted at 6:58 am on Feb 8th, 2009 by Demo

manuel and spadefinger are lying, people in venezuela can’t afford batteries of any kind, even of the lemon kind.

Posted at 7:48 am on Feb 8th, 2009 by cyanide

Except that Venezuela is part of mercosure and makes tons and tons of money

Posted at 8:29 am on Feb 8th, 2009 by riiiight

a quick look at the site shows that this is powered by a battery charger, not by the battery itself

Posted at 11:41 am on Feb 8th, 2009 by andres

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”

Posted at 1:30 pm on Feb 8th, 2009 by Demo

i stand corrected

Posted at 2:39 pm on Feb 8th, 2009 by andres

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.

Posted at 6:22 pm on Feb 8th, 2009 by James

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?

Posted at 10:43 am on Feb 10th, 2009 by j9

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.

Posted at 9:26 pm on Feb 15th, 2009 by kmpres

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.

Posted at 9:44 pm on Feb 15th, 2009 by kmpres

This is a fantastic hack, thank you.

Posted at 11:02 pm on Feb 15th, 2009 by arthur

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

Posted at 6:45 pm on May 8th, 2009 by s r venka rao

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!
Bryan

Posted at 3:48 pm on May 27th, 2009 by Bryan

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.

Posted at 5:51 am on May 28th, 2009 by kmpres

a fantastic modification indeed!

Posted at 3:24 am on Jun 11th, 2009 by new car lemon laws