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120V DC Lead battery desulfator!  Lightbulb and Bridge Rectifier!
120V DC Lead battery desulfator!  Lightbulb and Bridge Rectifier!
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Old 24th February 2012, 07:16 PM   #121
speakerfritz is offline speakerfritz  United States
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My dads Toyota is 9 years old, on its original Yuasa battery and has covered only 25K miles from new. It gets the worst use imaginable for a car. It does a 0.5 mile "paper run" daily + shopping... that's at least two and sometimes three or four starts a day. Heated window on, blower on full and sometimes headlights too and its still going strong.
I love these kind of stories. I used to test my batteries and calculate how much state of charge capability they would have. Not an exact science. On one car, I blew a regulator which on most cards is imbedded in the computer unit. So 800 bucks later and a new battery, I was back on the road. Batteries are so inexpensive, that I decided just to replace them at a specific interval. So two years on each registration renewal.
Old 24th February 2012, 07:36 PM   #122
Jacksonn is offline Jacksonn
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Default FLA Battery Restoration

Originally Posted by speakerfritz View Post
where does all the sulfur go....you know...the sulfur that was on the sulfated plates? well it collects at the bottom of the battery with the lead particles that get dislodged from the battery. what to do? You need to shake the battery up and pour the contaminated acid out. refill with new acid. Otherwise, you run the risk of shorting a few cells.
I used to pick up batteries & shake them, but I found a small hard stream from a hose, with battery on alternate sides, is effective. If an outdoor waterproof shake table was over my hole ... My first rinse, with warm water, helps to loosen debris on bottom. 160-180* F would be more effective, but I don't want to soften plastic. Water heater drain should cool enough through 150' hose.

One stubborn battery had to be rocked back & forth on the ground -- but I didn't have to hold the 50# battery at arm's length. A good LED light allows inspection of a portion of lower battery after rinsing.
Old 13th September 2012, 02:02 AM   #123
PB2 is offline PB2  United States
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I finally got around to building one of these but I used a half wave rectifier and a 60W light bulb, can't seem to find a 100W around the house. I read somewhere to use 3 100W bulbs in parallel to get around 1-2A. About those using a capacitor in place of the bulb - you have to consider that the bulb provides a temperature dependent resistance. It worked well on our ride on mower battery that has not held a charge for 5 years, we were jumping it everytime to start it LOL! Now it works!

We also have an extra old car that often goes for weeks at a time without any use often with the battery being dead. We get about 1-2 years out of a battery so I tried it on our most recent dead battery. It would only charge at about 3-5A on the 15A setting of our charger before desulfating, then charged at 15 A after tapering down to a full charge so it seemed. However, when I went to start the car it had little current available and was barely able to turn over the motor. I first ran the desulfator for 2 days and when it didn't work left it on for another 5 days, after this it hardly charged taking only 1-2A. The battery measures about 12V with no load so I don't think any cells are shorted. I'm thinking that I need to get the current up with the desufator and am going to try at least 2 100W bulbs.

I think I'm going to get a new battery and just keep it on a battery maintainer when we are not using the car.

Has anyone tried the Epsom salt trick discussed here:
Desulfating batteries with epsom salt

Several people mention that much older chargers would put out more voltage, forcing more current and "boiling" the electrolyte to remove the sulfation but I think that the "boiling" is just a much more rapid reaction producing many more hydrogen bubbles. Not sure if this actually acts as a desulfator or not.
Old 13th September 2012, 02:49 AM   #124
DigitalJunkie is offline DigitalJunkie  United States
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The 'boiling' helps mix the electrolyte,as well as helping to knock some of the sulfation/scale off of the plates..as I understand it.

Keep an eye on the electrolyte levels,and add a bit of distilled water if needed. I like to use a large syringe (without the needle!) to squirt in a known amount of water at a time.
The level tends to vary a bit,depending on the manufacturer,size,etc. just make sure that there's at least enough electrolyte to fully cover the plates,but not filled to the brim,and the level is similar in all cells.
Old 14th September 2012, 05:20 PM   #125
PB2 is offline PB2  United States
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I have to wonder if the advantage of this system is more the fact that it is closer to a constant current SOURCE more than the fact that it is pulsed. The high voltage available makes it possible to overcome high resistance in the batterY and force it to charge, probably desulfating while charging. Might not be significantly different than the old method of applying more voltage to force a charge.
Old 14th September 2012, 06:30 PM   #126
Arty is offline Arty
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i dunno, i have tractors and winter does indeed kill batterys in them.
My resurrection methood differs a bit...
I usualy scrape the plates inside the battery a bit if they fail to accept charge from a charger.
Then i simply put it on a regular charger, and wait. Usualy it takes a week or soo to get it full.
My charger has option to limit max current.
I set it to 1/10 th of the Ah rating of the battery.
After charging finished i change the electrolite solution. Good idea to wash the battery. I use a small diameter hose i can push down to the bottom of the battery cell, turn the thing upside down and let tapwater in. it washes out the conductive "goo" / "stuff" from the cell. Then i fill it with new electrolite after i washed all cells.
So far it works good, the re-conditioned batterys have good capacity.
My bigger tractor has a 5 liter diesel without any glow plugs or decompression valves, and my reconditioned batterys seem to do the job year after year.
Old 15th September 2012, 01:58 AM   #127
PB2 is offline PB2  United States
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Just remembered that the flood lights out back are 150W trying one now overnight.

I'm thinking of buying a 500W bulb and since this is half wave it will act as 250W with a rather high peak current. I calculate a peak current of about 5.9A with a 500W bulb but it might be even higher since the bulb will run colder at the lower power level. I calculate about 2.1A RMS with half wave rectification. I think this bulb might bring down the times to finish desulfating and might work better with the higher current. One would want to check the battery for temp, gassing, and try to avoid overcharging at this much higher rate since there is no automatic turnoff.

Those are probably some big batteries that you're talking about Arty. I'm a bit nervous about working with the acid and would be more inclined to buy a new battery at that point but I have heard that what you're doing does work.

Last edited by PB2; 15th September 2012 at 02:03 AM.
Old 31st December 2012, 07:56 AM   #128
EWorkshop1708 is offline EWorkshop1708  United States
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Hey, glad to see this thread still running and you folks trying this 120V desulfator in different ways.

I made another one with a large 25uf 250V capacitor from a scrapped Air Conditioner, feeding into a 6A bridge rectifier. A bit more current, but a bit faster, and you see some bubbles in the cells after a while.
You can call me Mad Professor, building crazy experiments in my Electronics Workshop
Old 21st January 2013, 02:42 PM   #129
cpuneck is offline cpuneck  United States
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Well I'm assembling one of these gems and haven't seen much info on how the rectifiers are assembled (types, specs, etc.)

I have a diesel truck that sits a lot. I was late with installing my solar trickle/desulfator and the batts (yes two of them, type 65 1000CCA ea!) are certainly sulfed up. (~12.0v at rest )

I'm not trying to scrounge parts or build for pennies, I'm purchasing new components and so far have a 0.22ohm MFR, 1W @5% (fuse), one 4.7ohm Wirewound resistor, 5W @5% (reverse protection), and one 7.5uF Run/Start Cap, 370VAC @ 5%. Now I just need rectification . I considered gutting one of my old PC power supplies, but I'm not sure I'd have success.

I was going to use the PC power supply to charge after I desulfated because I've lost confidence in automotive charges. I have an older Sears 70/12/2 6/12v "smart" charger, it just swings the amp meter wildly with the "charged" light flickering on and off. Probably due to the sulfated plates causing the charger an over volt condition... don't know. Anyway, thanks to all for the great, informative, hard to kill thread!
Old 26th January 2013, 07:51 PM   #130
cmdrdata is offline cmdrdata  United States
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Originally Posted by EWorkshop1708 View Post
Hey, glad to see this thread still running and you folks trying this 120V desulfator in different ways.

I made another one with a large 25uf 250V capacitor from a scrapped Air Conditioner, feeding into a 6A bridge rectifier. A bit more current, but a bit faster, and you see some bubbles in the cells after a while.
I am trying to scrounge up parts to use the cap version, but didn't know where they are (I am sure I have these parts but being a pack rat, I cannot find them when I need them). So to try that right away, I use a single power diode (thus only halfwave rectified instead of fullwave like your version) and 40W incandescent lamp to de-sulfate two sealed lead acid batteries that I have lying around. Will update this post tomorrow with my de-sulfating result.

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