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Old 02-09-2007, 01:04 AM   #1
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GP3700, Are my cells dead?

I have 3 packs of GP 3700 cells, none of which will take more than 3200mah when charged at 5amps, or output more than 2600mah when discharged at 20amps.

So I have disassembled the worst pack. I have then charged (5amps) and discharged (20amps) 3 of the cells individually. Below are the figures

Cell 1
Charge : 1351mah in 971 seconds
Discharge : hit cut off voltage (0.9v) within 10 seconds

Cell 2
Charge : 1288 mah in 928 seconds
Discharge : 209 mah in 40 seconds

Cell 3
Charge : 1289 mah in 929 seconds
Discharge : 271 mah in 49 seconds

Are these typical ? If not, what level figures for charge and discharge should I be getting?
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Old 02-09-2007, 05:31 AM   #2
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Clearly that is not typical as the cells are nominal 3700mAh.

Those cells are obviously bad, you ay be able to salvage one or two packs from the rest of your cells if you go through and cycle each cell.
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Old 02-09-2007, 05:38 AM   #3
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Thats tipical of a bad cell.

I rematched some time ago 3 3000HV packs.

What i did was: desolder all cells. Cycled them and take notes of the values. I labeled them a, b, c, d,...

In the end i found out 5 cells would lose voltage under load just like yours. Those went to the garbage and the others went for 2 'rematched' packs. They are still crappy packs, but a lot better then before.

Hope it helps.
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Old 02-09-2007, 07:20 AM   #4
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Default OK, which new cells

I suspected as much. So it looks like time for some nice new cells

My budget is approx 40 per pack, my choices appear to be

Demon Fire cracker
Demon IB 4200 WC (matched)
GP 3700 (unmatched)

Which do you think will be the best option for 27T & 19T tour cars?
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Old 02-09-2007, 07:24 AM   #5
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Grab the shovel and dig a hole.
But thats a whole other thread.
I like the 3700 matched if you can get'm.
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Old 02-09-2007, 07:56 AM   #6
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Id go for the ib4200wc, not used the fire crackers so cant comment on them but i've used demon's gp3700 for a year @ 6A and had no problems with them, however the newer IB's will have the edge on voltage
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Old 02-09-2007, 08:45 AM   #7
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I would definitely go for the IB cells for stock and 19t. I have a couple Orion Team 3700 packs that are 1.193+ and they still don't hold a candle to even a pretty decent 3800 IB. Even a very average 4200's will still be 1.210+ and you can find those for a very reasonable price.
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Old 02-09-2007, 10:29 AM   #8
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Hi mate i would go for the Demon IB SC-4200 World Champion Edition Blue Matched batteries as these cells are awsome and if you are racing stock then you need the IB as there voltage will be higher than the GP3700's. The fire cracker cells are ok as a cheaper practice pack but i would definitely stick to IB if you have 40 to spend on each pack.
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Old 02-13-2007, 02:53 AM   #9
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I have found some new unmatched GP3700 cells at a really good price.

As an average club racer, would I be able to feel the difference between matched and unmatched cells?

Am I right to be concerned about all the stories of IB4200 WC cells exploding.....!!!
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Old 02-13-2007, 03:56 AM   #10
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If you are only club racing, you probably wouldnt notice the difference
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Old 02-13-2007, 07:57 AM   #11
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I've seen'm vent at our track people keep charging them at 7 & 8 amps to get the punch of 3700 pack charged at 5 or 6 amps. I've never had a GP 3700 vent.
I feel 3700's were the last hearty cell, they just got weaker after that, and they dont last as long.
You have to baby the new cells they just dont seem to be as strong in my opinion.
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