# Reviving AGM batts



## grose (Apr 30, 2008)

I have two 12V, 110AH AGM batteries that have lost a substantial portion of their capacity. Is there any way to revive these or should I get new ones?


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## TheSGC (Nov 15, 2007)

grose said:


> I have two 12V, 110AH AGM batteries that have lost a substantial portion of their capacity. Is there any way to revive these or should I get new ones?


What are you using for a charger and how old are the batteries?


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## grose (Apr 30, 2008)

TheSGC said:


> What are you using for a charger and how old are the batteries?


Charger is a Schumacher 12V 6A smart charger. The batteries are a year old and have 1600 EV miles on them.


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## rebenergy (Apr 18, 2008)

Hi grose
My advice is just off the cuff and I am leaving for vacation, so I can’t provide any links to support my statements at this time. A Schumacher 12V 6A smart charger may not provide enough current to equalize the batteries. (Equalizing is the causing of bubbles to move by plates mixing electrolyte and chafing the lead sulfate crystals off the plates). If the batteries are sulfated a few good equalizing charges may help. You could then follow this process by topping off the electrolyte by adding standard battery acid, _NOT distilled water_. This will not damage old batteries, but gives them a second wind. If you have the time you could buy a high frequency desulfatetor. I have heard good reviews, but have not yet used one my self. I do not believe in using cleiagents (sorry bad spelling) like EDTA. They encapsulate the lead-sulfate crystal sloughing so much sludge to the bottom of the plates and sorting them out. 

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## ww321q (Mar 28, 2008)

I have had some luck desulfating regular lead acid and gel cells . How come just 2 batteries ? I'm sure your string is longer ? They could be dried out from high discharge or to high voltage when charging . there are desulfaters that you can build to . The Schumacher chargers I have , have one built in . I also have another I bought . 
[h2]BLS-12/24B[/h2]








http://www.batterylifesaver.com/products/products.htm
hope this helps J.W.


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## TX_Dj (Jul 25, 2008)

rebenergy said:


> You could then follow this process by topping off the electrolyte by adding standard battery acid, _NOT distilled water_.


I don't see how this is a possible suggestion with sealed AGM batteries.


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## grose (Apr 30, 2008)

ww321q said:


> I have had some luck desulfating regular lead acid and gel cells . How come just 2 batteries ? I'm sure your string is longer ? They could be dried out from high discharge or to high voltage when charging . there are desulfaters that you can build to . The Schumacher chargers I have , have one built in . I also have another I bought .
> [h2]BLS-12/24B[/h2]
> 
> 
> ...


Just two batteries are showing this weakness in the string. The others load test better. How successful are these desulfaters? Are there any verified results that they work? (other than anecdotal)


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## adric22 (Jan 17, 2008)

TX_Dj said:


> I don't see how this is a possible suggestion with sealed AGM batteries.


You took the words right out of my mouth. I was about to mention the same thing. Not only can you not add acid to an AGM, but I don't believe you want any bubbles forming in there. Bubbles are very bad for AGMs.


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## judebert (Apr 16, 2008)

adric22 said:


> You took the words right out of my mouth. I was about to mention the same thing. Not only can you not add acid to an AGM, but I don't believe you want any bubbles forming in there. Bubbles are very bad for AGMs.


On the EVDL, none other than Lee Hart himself suggests that some AGMs can be saved by drilling a small hole (7/64", I believe), adding the fluid, and sealing the hole with silicon and a #7 screw.


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## TX_Dj (Jul 25, 2008)

It certainly doesn't surprise me that Lee would do something like that. And if he has, and was successful, I would trust his data on the subject... question is, does anyone have a link to his findings?


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## judebert (Apr 16, 2008)

Well, his advice is mentioned in this thread:
http://www.diyelectriccar.com/forums/showthread.php?t=15499


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## grose (Apr 30, 2008)

judebert said:


> Well, his advice is mentioned in this thread:
> http://www.diyelectriccar.com/forums/showthread.php?t=15499


Jude,

I just got done reading that thread. What did you end up doing with your two "stinkers"? 

If I substitute two new batteries in place of the old ones my pack will be uneven aged. I'd have seven that are a year old and two new ones. I presume this will be hard on the new batteries.

I found the idea of drilling a hole and adding di-H2O interesting. A big assumption you are making there is that each battery is going to have exactly the same weight. I'm sure there is some variation that exists when they are manufactured.


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## TX_Dj (Jul 25, 2008)

From the same thread that Jude linked - "Dont' do it!" was the advice for putting new batts in with old batts. This is in line with the same advice I've always heard.


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## JRP3 (Mar 7, 2008)

I would try a larger smart charger with an equalization setting.


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## judebert (Apr 16, 2008)

grose said:


> Jude,
> 
> I just got done reading that thread. What did you end up doing with your two "stinkers"?


I removed them. I took a big hit to range, not just because I lost 1/6th of my batteries, but because the rest are damaged and unbalanced. I had trouble just this morning; I'm considering just buying a complete new pack.


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## morvolts (Jun 19, 2008)

Are any of them warrantied?
All my redtops have a 3 yr free replacement
dont know about the yellows.
Local store here has Yellows on sale for $150
Optima is doing a $25 rebate now too.
limit is 2 per customer tho.


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## TX_Dj (Jul 25, 2008)

morvolts said:


> Are any of them warrantied?
> All my redtops have a 3 yr free replacement
> dont know about the yellows.
> Local store here has Yellows on sale for $150
> ...


Wow. That's a damn good price for YTs, based on what I've seen recently.

I wonder if there's anyplace local that is similarly priced. I have enough friends that I could get a whole set.


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## rebenergy (Apr 18, 2008)

Quote:
Originally Posted by *rebenergy* http://www.diyelectriccar.com/forums/showthread.php?p=63729#post63729
_You could then follow this process by topping off the electrolyte by adding standard battery acid, NOT distilled water._

I don't see how this is a possible suggestion with sealed AGM batteries. 


MY BAD, I TOTALLY OVER LOOKED THAT DUE TO BEING TIRED AND VACATION BOUND. 
_Thank you for not giving me a well deserved FLAMING. _


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## rebenergy (Apr 18, 2008)

I am still on vac. and just got near a computor


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## TX_Dj (Jul 25, 2008)

rebenergy said:


> Thank you for not giving me a well deserved FLAMING.


No need to flame ya... it was an oversight, perhaps, but as Jude showed us, it has been done, though with water and not acid...


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