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Old 05-24-2007, 07:44 AM   #16
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Guys,

I have done a ton of research on this "bad cell" thing.

The truth of the matter is you can bring them back to amazing #'s! I have a process that most of the battery Co.'s don't even know about...

I have taken old junk packs and brought them back to life almost to original #'s! There is really no such thing as a bad cell... like the guy earlier said they just get out of balance. His process is very close to mine.
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Old 05-24-2007, 09:10 AM   #17
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This was a new pack of unassembled cells and the suspected "bad cells" vented on the first charge. It may have been that the cells that I thought were bad were just at a different charge state when I assembled the pack. It's probably a good idea to disharge each cell down to .9 volts before assembling the pack and charging. Now I'm wondering about those "bad cells" that I threw in the trash. I'm gonna dig them out and cycle them and see what kind of numbers I get.
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Old 05-24-2007, 04:43 PM   #18
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Quote:
Originally Posted by Pull_My_Finger
It may have been that the cells that I thought were bad were just at a different charge state when I assembled the pack. It's probably a good idea to disharge each cell down to .9 volts before assembling the pack and charging.
You can assemble the pack prior to equalizing the cells for charge / cycle.
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Old 05-24-2007, 06:26 PM   #19
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This is very interesting. After discharging on the DPD, my cells have these voltages - from cell 1: 1.14, 1.14, 1.18, 1.19, 1.16, 1.17.

The cells are IB 3800's.

Sosidge, I don't quite understand point one in your routine...

Quote:
Originally Posted by sosidge

1. Check individual cell voltages under no load, they should all be around 1.2V - if one is at 0V or at anything well below 1.2V it is out of balance - however IB's can go down to 0V occasionally without failure, and just need coaxing back to life. If a cell is at 1.6V or something even higher than that it is probably totally shot, I have seen a few cells do this (normally cheap stick pack cells).
Especially where it says "If a cell is at 1.6V or something even higher than that it is probably totally shot".

What do you mean?

Thanks for this information, it is really great.

Cheers,
Warwick.
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Old 05-24-2007, 06:57 PM   #20
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sounds like a good reason to go......oh man, I wont say it and get flamed eff it LI-PO!
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Old 05-25-2007, 03:51 AM   #21
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Quote:
Originally Posted by bxpitbull
sounds like a good reason to go......oh man, I wont say it and get flamed eff it LI-PO!
Of course, Lipo cells never deteriorate and never go bad! 0% failure rate on LiPo's, industry fact, just read the forums!

Get out of the thread if you don't have anything helpful to say. All the LiPo fanboys seem desperate to convince themselves that they have made the right choice, and can't stop flaming the NiMH forums.

Grow up please.
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Old 05-25-2007, 03:54 AM   #22
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Quote:
Originally Posted by B4Bandit
This is very interesting. After discharging on the DPD, my cells have these voltages - from cell 1: 1.14, 1.14, 1.18, 1.19, 1.16, 1.17.

The cells are IB 3800's.

Sosidge, I don't quite understand point one in your routine...



Especially where it says "If a cell is at 1.6V or something even higher than that it is probably totally shot".

What do you mean?

Thanks for this information, it is really great.

Cheers,
Warwick.
Sometimes you will have a cell with a crazy high voltage, even when discharged. I've only seen it on cheap stick packs that have gone funny.

Are the voltages you list above the resting voltages after the DPD has finished? If so they are quite imbalanced but I wouldn't say you necessarily have a single bad cell, just an old, tired pack.
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Old 05-25-2007, 07:28 AM   #23
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Quote:
Originally Posted by sosidge
........Are the voltages you list above the resting voltages after the DPD has finished? If so they are quite imbalanced but I wouldn't say you necessarily have a single bad cell, just an old, tired pack......
They are the voltages on the DPD readout after the pack has cycled. They all have pretty crazy internal resistance too (5.2, 4.6, 3.7, 3.3, 4.5, 4.5).

Will following your steps bring the cells back to life (increase the voltage)? Can you reduce resistance in IB cells once it is that bad?

Thanks for your reply,
Warwick.
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Old 05-25-2007, 08:45 AM   #24
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Quote:
Originally Posted by B4Bandit
Will following your steps bring the cells back to life (increase the voltage)? Can you reduce resistance in IB cells once it is that bad?
You can't bring cells back to where they were, unfortunately they deteriorate the more cycles they have on them, and until we have a time machine packs will just get worse as they age!

My tip for a slow charge is just to resuscitate an IB that has dropped to 0V in storage.

Really all you can do is give them a couple of equalise/charge/discharge cycles to get the pack as evenly balanced as possible.

As I said, it looks to me that you don't have a particular bad cell in the pack, rather an ageing pack with several cells that are past their best.
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Old 05-25-2007, 03:25 PM   #25
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Quote:
Originally Posted by sosidge
You can't bring cells back to where they were, unfortunately they deteriorate the more cycles they have on them, and until we have a time machine packs will just get worse as they age!.....
Thanks for the tips mate, luckily these are not my race packs

Kind regards,
Warwick.
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Old 05-25-2007, 05:57 PM   #26
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Sosidge,

You are wrong about the batteries...

I have a friend who woked for Sanyo back in the 90's. He was instramental in the design of the 1200sc, 1200scr, 1400 scr and 1700 sce cells.
There is a way of restoring anything but a super vented cell. trust me.

I am a c main racer at big events ie cleveland, snowbirds ect.

I ran 6 battery packs all year long.

Travis
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Old 05-25-2007, 06:11 PM   #27
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Usually I have tons of extra cells. So I will mix cells from one pack to another as long as they are are same chemistry, brand, and capacity.

I have always used a voltmeter. I remove the cell that has obviously a different voltage than the rest of the pack.

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Old 05-25-2007, 07:27 PM   #28
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Quote:
Originally Posted by march to my own
I have a process that most of the battery Co.'s don't even know about...

Sosidge,

You are wrong about the batteries...

I have a friend who woked for Sanyo back in the 90's. He was instramental in the design of the 1200sc, 1200scr, 1400 scr and 1700 sce cells.
There is a way of restoring anything but a super vented cell. trust me.

I am a c main racer at big events ie cleveland, snowbirds ect.

I ran 6 battery packs all year long.

Travis
WOW can i borrow you and your friends magic battery wand when your done with it....This thread shows proven and explained methods, not just extravagent claims....Explain yourself

Great thread with really good advice,,if only we had the WEB when i started in the hobby.....you just have to weed some advice.
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Old 05-26-2007, 11:24 PM   #29
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Quote:
Originally Posted by march to my own
Sosidge,

You are wrong about the batteries...

I have a friend who woked for Sanyo back in the 90's. He was instramental in the design of the 1200sc, 1200scr, 1400 scr and 1700 sce cells.
There is a way of restoring anything but a super vented cell. trust me.

I am a c main racer at big events ie cleveland, snowbirds ect.

I ran 6 battery packs all year long.

Travis
OK, would you please give us the details of exactly what you do ?

We always have a market for new racers needing cheap stuff. If we can revive and either use or sell the older packs, it helps us save a few bucks for racing and also helps us bring in new racers to the track.
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