Author Topic: Battery de-sulphater  (Read 22955 times)

rcavictim

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Re: Battery de-sulphater
« Reply #30 on: May 04, 2007, 02:44:45 PM »
...  I've taken a few of these batteries home to play with and have had some decent luck getting them back to life.  There was one however that I believe had one bad cell (12v) as it constantly would drop to 10v once a load was put across it.  Unfortunately I recycled it so I don't have it to test anymore but I wonder if a desulphator would have brought this back to life after some rigorous charge thrown at it.

Robert

I recently got a batch of used telecom AGM 12 volt, 105 AH batteries.  One was found to have a completely dead cell and the battery would not draw more than a few Ma when 20 VDC was applied trying to charge it.  It measuread about 10.5 volts open circuit.  Seeing this as a worst case scenario I thought it woiuld be a great test subject to see if these pulse battery desulfators were really any good.

I spent last weekend building my own.  It took quite a bit iof trial and error getting the thing to work properly but I was cobbling together my own. heavy duty version of a basic circuit used as a guide only.  I recently took apart a number of computer and telecom switchmode type power supplies and have been gathering up the totoidal inductors and other components for my parts bins.  I used one of these coils as was and the core from another, winding myown wire on as appropriate.  My unit draws from 1/2 to 1-1/2 amps from the battery at 11-15 volts, adjusted by a pot and visible on a meter for tuning.  It requires a cooling fan on the semiconductor heatsinks and torroidal coils.  This is WAY more aggressive than the commercial battery minders you can buy in stores.  I wanted a unit powerful enough that could treat a whole bank of 12 volt batteries in parallel on a common bussbar system.

I ran my pulser on this dead AGM battery for about 30 hours with a trickle charger supplying the extra power necerssary to help run my pulser and to provide some charging voltage for the battery.  To my almost disbelief after 30 hours I had a battery that could accept 9 amps of charge from a real battery charger and not climb over 14.5 volts (at the present state of battery charge).  I tested the battery with a Xantrex-X power 1000 watt inverter as a load and it ran a 60 watt incanmdescent lamp great.  It was able to run a 300 watt incandescent lamp for several seconds before the low voltage alarm on the Xantrex squealed and then the inverter went into battery protect shut down.

This is amazing I think and looks to me like proof that this technique actually works.  I put the pulser back on last afternoon with a 2 amp charge and plan to check on it again today and slam it with another 300 watt test to see if there is a further improvement.

edit to correct typo stating Xantrex  inverter size
« Last Edit: May 04, 2007, 07:22:30 PM by rcavictim »
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Doug

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Re: Battery de-sulphater
« Reply #31 on: May 05, 2007, 02:33:38 AM »
We send out a lot of batteries with nothing wrong with them to be reconditioned because my employer has more money than brains ( in the old days we just tossed out perfectly good dead batteries lol ).

Anyhow thewy come back with a plastic desulfator pulse gizmo. Generaly the shaft crews, ad mobile guiys steel these before a battery arrives at a machine.

Do they work?
People keep stealing them.....

Doug
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rmchambers

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Re: Battery de-sulphater
« Reply #32 on: May 05, 2007, 03:00:05 AM »
Now that I have my inverter sort of set up the way I want (just not powering everything I want it to yet) I embarked upon some battery maintenance.  The consensus is that the voltage of each battery should be with in tenths of a volt between each cell in the string.  I have 4 in my string.  With the old batteries I got when I purchased the inverter I don't know how old they are or how much  they've been abused.  I topped up to the recommended level with distilled water and measured.  I wasn't with in a few tenths of a volt I was almost a volt off on some of them  >:(

Ok, time for an equalization charge.  Look at the instructions.. looks simple enough, turn the little knob to equalize and away we go right?  wrong.  the voltage didn't change at all!  argh I have a defective inverter.

I chopped the incoming A/C to the inverter and forced it to run off the batteries.  Turn the power back on and now I hear a heavy duty hum coming from the inverter and the 26-something volt float voltage is now 33volts!  yahoo.. the batteries start bubbling and I let it run (had the window open)  when I came back down the next day the inverter was back to normal voltage so I turned it back to normal.

Measured the voltage between the batteries and they were all within 1/10 of a volt of each other.  Good news...

So I'm guessing if you have a decent inverter that has that option it may not be necessary to run a pulsing desuplhator.  But if you have a lame battery it might be the only thing that can bring it back to life.

Robert

Doug

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Re: Battery de-sulphater
« Reply #33 on: May 05, 2007, 03:09:59 AM »
Its not the same thing but the Nic Cad batteries I service that provide the back up power to the 13.8 kV switch gear at work has an equalization pulse charge. I hit the button and it hits the stack with a high current pulsing charge to blow the wiskers off the plates. Seems to me that the same thing will knock the hard sulphate off a lead cell given a little time.

That much said when you blow the hard sulphate crystals off a lead plate, they fall off and sink to the botom of a cell. My point is you shouldn't let a battery discharge too long and form a hard sulphate on the plates do to lack of proper charging and reconditioning charges in the first place.

My Johny light has Nicads in it. I perform a recon charge every month and get a light that lasts a shift. Some guys can't get their batteries to last a full shift and send them to the lamp man who fixes them at his own pace.......
( a loner cap lamp from first aid is like borrowing a mecanics spare car lol)
Doug 
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rmchambers

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Re: Battery de-sulphater
« Reply #34 on: May 05, 2007, 03:32:44 AM »
the pulsing desulphater knocks the crystals off the plates.  the equalization charge "boils" for want of a better word, the electrolyte and stirs it all up so it doesn't stratify with the more concentrated acid at the bottom and mostly water at the top layers.  That's the way it was explained to me anyway.

As for Nicads, I had some in my aviation handheld radio, horrible things.  I found a site on the net that sells the same shape/size/voltage battery in NiMH and ordered enough to rebuild my battery pack (fiddly job).  I've been very happy with the results, so much so that I rebuilt another pack.  My radios outlast any Nicad pack powered ones.

Doug

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Re: Battery de-sulphater
« Reply #35 on: May 05, 2007, 03:36:59 AM »
I deal with flooded wet cells.

The caustic burns my hands.......

They suck, unless I can get some for free and take them home. Everything changes then lol.
It's a Good Life, If You Don't Weaken