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Old 02-05-2009, 08:17 AM   #1
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Default Battery problem

I've got a 5S Zippy Rhino 4900 that I've run about a dozen times. I charged it one night then went to use it the next day. I plugged it into the charger just to get a reading on the voltages. Turns out cell #1 is at 4.04V while all the others are at 4.18-4.19. I figured I'd try balancing it but after 30 minutes cell #1 is still at 4.04V. So I take it for a spin anyways. I set the cut off voltage to 16V rather than 15V just in case this cell drops faster than the others.

After 30 minutes or so of bashing I take it back, let it cool off then throw it on the charger. Cell #1 is down a bit more than the others, 3.56V with the others at 3.60ish. I balance charge it but cell #1 is always 0.1-0.05V below the others as it charges. Sure enough, it stops at 4.04-4.05 with the others going to the full 4.20.

Is this cell dying? Should I stop using the pack or just live with the lower voltage on this cell? It sucks I have this problem after only a dozen runs or so. Anyway to "reset" the cell as it is?
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Old 02-05-2009, 08:33 AM   #2
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This is interesting…..I have 2 brand new Zippy packs that came out of balance by around ~.05v. Both packs came with a low initial charge ~30% which I found odd as well. Up till now all the Zippys I have gotten have shown up perfectly balanced and at around 50-70% charge.

What’s even stranger is I have a Hyperion Duo charger which seems to refuse to balance them in a reasonable amount of time. I have a passive stand alone balancer which after several hrs balanced the cells and then they took a 100% charge. I am yet to track test these packs but one pack I ran around in a Brushless Hyper ST for a while and then looked at the cell Voltage. With the pack ran down to around 70% all cells were still balanced and easily charged to 100% with out any problems.
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Old 02-05-2009, 08:54 AM   #3
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Wierd. I wonder if it's simply the battery then. Either way, I'm going to continue to use it and see what happens. It's still a very strong pack. I can't notice any difference in performace or longevity of the pack. Hopefully the low cell maintains its voltage. If it starts to dip further I'll probably have to retire it. Does anyone have experience in removing/adding cells to a pack or is this a no-no? I wonder, if things get worse, if I could simply remove the cell, remove the balancer wire for that cell and make the pack a 4S.
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Old 02-05-2009, 09:12 AM   #4
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On the first pack I tried to balance first; when that was taking to long I just tired a balance charge. The charge timed out with the pack at 97%. All cells took a good charge and the voltage diffrence remained about the same. In other words like yours one cell just wanted to stay behind the others. After using my stand alone balncer that cell finally balanced with the other cells and then it took a full charge no problems. The senario is strange, I can't wait to track test these packs and see how the cell votages hold.
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Old 02-05-2009, 09:44 AM   #5
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Maybe I'll try that then. I only balance charged it for 30 minutes or so before I stopped it. I was worried that continuing to try to charge the cell when the voltage wouldn't increase might damage it (further?).
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Old 02-05-2009, 10:03 AM   #6
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Quote:
Originally Posted by Ryandrea View Post
Maybe I'll try that then. I only balance charged it for 30 minutes or so before I stopped it. I was worried that continuing to try to charge the cell when the voltage wouldn't increase might damage it (further?).
If that cell is unable to accept a charge past 4.04V then I would be very weary of the pack. I think at 97% my one pack had the low cell at 4.09 and the rest were around 4.14 or so. After doing a passive balance and then 100% charge that cell rose to 4.19V along with the others.
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