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DIY Battery rejuvenator cheap and easy

22265 Views 6 Replies 5 Participants Last post by  Brian Burton
Upon doing some traveling the past few days I stopped over at a bed and breakfast in which I had a discussion with a fellow who had bought an expensive battery rejuvenator. I have heard of others just using AC to fix the sulfate problem, but never really looked into it since I usually had batteries under warrantee I could return and get a new one. I am pretty hard on batteries and usually they go out before the due date is up on them, so new ones are always ending up in my cars or shed for solar.

However, after looking at the prices of battery rejuvenators and leaving a pile on the floor behind me, I decided to find a cheaper way to fix the sulfated problem if I have to do it and save a battery. Especially in these tough times and some day I may not be able to afford a new battery.

I wanted to build my own, so I looked around.
So in my digging, I found several things mentioning using AC to create a higher charge in the battery to de-sulfate the battery. Upon the search I ran across a website talking about battery rejuvenation. It included plans how to build your own battery rejuvenator.
You can look through it here:

The diode bar (white mark on diode) should be facing (closest to) the positive side of the battery. (For those who don't know how to read diodes on a schematic.) Has a mark similar to this >l on diagram.
Radio Shack PN 276-1144

Now this is taking AC and using just one side of the power to run through the battery. Now this fits other information I found on using AC to rejuvenate a battery. Using the light bulbs to control the current used is also in conjunction with other various types of AC battery rejuvenators in the fact there is a controlled amount of amps that enters the battery. The other way was using pulses, in which making your own pulse generator you could do it the other way too. Probably something on the web about DIY pulse generators for battery rejuvenation. However, this setup (which I first thought came from the Red and Green show) seemed to have what it takes to get the job done at a far cheaper price.

If anyone on here knows me, I am good at being cheap. haha
Put me in the Red Green show and I will fit right in. =)

So read through the tractorbyte blog and see what you think. It just makes sense to find ways to save our batteries that can be saved by also saving a few more dollars from buying an expensive battery rejuvenator. (Some are over $2,000). I will never pay for a battery rejuvenator that costs more than my car did. haha

So if you are like me, you may have a battery sitting around that is not worth its weight now anyway and you may want to try his battery rejuvenator idea out.

I plan to try it out once I get home. So has anyone tried something like this before or something similar to rejuvenate batteries?
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I had a go at restoring 3 dead batteries using my auto-store rejuvenator a couple of years back with mixed results.

One of the batteries improved enough for me to use it in series with another (in order to move the EV up & down the driveway).
The other two batteries I tried to rejuvenate didn't budge however. They were still very large paperweights.

You've got nothing to lose, so best of luck and be sure to post your findings!
Kiwi, I read more about the rejuvenator and the aspects of it, then found that some were still able to recover old dead batteries by doing it several times, some up to 5 times to get the batteries back to normal. Then if it is a dead cell (sulfated shorted the cells from buildup) it can still be recovered in other alternative ways. But usually using the rectifier pulse will eventually keep working on breaking down the sulfate in the battery. In some cases if the sulfate builds up too much in the bottom of the battery, they battery may have to be drained (yes a pain I can imagine to some degree, but can be done safely) to get the sulfate out, then filtering the acid/distilled water mixture to get the sulfate out and putting it back in is key to prevent another short in the near future.

Been reading up on it quite a bit, but finding all those batteries I took to a recycle center could have been saved one way or doing the other. I won't be throwing out any batteries now.

I tested one battery and had great results, it came back restored using the home made rejuvenator. I admit, I had a long extension cord away from it when I plugged it in to begin with, but after 24 hours it was still intact and when I put it on a charger, within half a day it was reading full charge. Then load tested it and it said it was good. That saved me a few bucks right there, so I will be using it on all other batteries for now on.

I keep thinking, why didn't I think about this earlier? Goodness. haha
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There’s a new way called EZbattery ( ) to bring nearly any type of old battery back to life so it’s just like new again. This method works with nearly every type of battery out there ...and it’s simple and quick. In case you’re wondering, you’ll be able to bring car, phone, and laptop batteries back to life with this. It even works with solar/off-grid, marine, golf cart, and forklift batteries. Plus, many more!
Complete garbage as are most all battery rejuvenators.
With respect to Lead Acid batteries there or two types of Sulfation: Reversible (Soft crystals) and Hard.

Reversible sulfation is the normal charge/discharge process. Once a Pb battery is less than 100% SOC soft sulfate crystals begin to form. The deeper you discharge, the faster the process accelerates. Normal charging is able to dissolve most (not all) soft lead sulfate crystals.

Hard sulfation is not reversible. Once the lead sulfate hardens and form a solid hard crystals, game over you cannot dissolve them.

The so called magic rejuvenators all do the same thing. They apply an over charge voltage to dissolve as many of lead sulfate crystals as possible. If you find yourself having to try to use one means you screwed up from the day you bought the battery. You failed to use a hydrometer and apply a Equalization Charge when you hydrometer indicated a problem. Equalization is a controlled over charge, and any decent Lead Battery Charger has an Equalization Stage for maintenance of Pb batteries.

Before you go willy nilly applying an over charge think twice because it does permanent damage. It corrodes the battery plates, and thus why you only EQ when your hydrometer tells you to do so. On average once a month.
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I found that the best way to restore a lead acid battery was with the Capacitor dump circuits it doesn't take long for their internal resistance to drop significantly.

With the inductive kickback spike method although it did work i had problems with cell shorting which i presume was dendrite growth or something.

They do work, you can prove it with a IR meter and a watt meter, it doesn't take long to have a noticeable effect, - its just they are never going to be as good as a new battery.
for information on battery reconditioners and desulfators suitable for electric cars with lead acid batteries check out this link
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