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Old Jun 29, 2003, 06:02 PM
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Goshen, Indiana, United States
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What rate to charge lipoly cells?

Looks like I am going to get a pack of 1200 3s3p lipoly cells (3600 mAh)

What is the recommended charging rate for this pack? I can go up to 2.5 amps on my triton.

How about discharge rates?

I suppose I set my discharge and charge voltage to 11.1.
Right?

Thanks!
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Old Jun 29, 2003, 06:13 PM
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Hi again,

You don't need to discharge the Lipo's because they don't have any "memoryeffect"
Charging is always no more then 1 C , thus 1200 mA for the E-Tec 1200's

Peter
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Old Jun 29, 2003, 06:13 PM
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Stavanger, Norway
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Termination voltage is 4,2V/cell.
LiPo's will take 1C charge just fine (3,6Ah in this case so 2,5Ah is no consern)

Discharge, they state 90% capacity at 5C (=16A)

I'm flying a model with 2s3p E-Tec1200's, static amps around 15, flighttimes 35-40minutes.
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Old Jun 29, 2003, 06:16 PM
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The packs are 12,5 V when fully charged but I don't need to set the voltage on my Orbit charger, do you use the Lithium Ion program on your Triton?
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Old Jun 29, 2003, 06:42 PM
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Danville Vermilion, Illinois, United States
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For the triton, use the nominal voltage for the setup, so yes, 11.1V (3.7*3) is correct.

I don't have any experience in the matter of parallel charging, but I've read that to be totally safe against cell imbalance, you should charge at 1C for the individual cells , rather than for the pack. in this case, 1.2A. This is a raging debate, however, and 1C for the pack is probably fine.
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Old Jun 29, 2003, 06:50 PM
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I got a guy from Illinois and Norway telling me different stuff on the charging rates

Do I charge it at 1C per cell or per pack?


I assume that Haldor is correct since he actually has pack that he has been charging (and that it would be nice to be able to charge it at 2.5 amps)
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Old Jun 29, 2003, 06:52 PM
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Oh, how do I treat a new pack?

Slow discharge and then charge at C/10 like a would NiMH?
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Old Jun 29, 2003, 06:54 PM
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On the discharge settings I need to chose voltage.

Choices are: 12v, 9v, 6v and 3v.

Which one if for me?
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Old Jun 29, 2003, 07:24 PM
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Haldor's advice is very sound.

I charge my 3S2P pack (2.4 Ah) at 2.4 amps on a Schulze , no problems to date.

so far, wonderful batteries.
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Old Jun 29, 2003, 07:44 PM
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Quote:
Originally posted by Cubby Boy

Do I charge it at 1C per cell or per pack?
Yes on both If you charge a single cell you charge it at 1C (=1,2Ah)
As your pack has three cells in parallell the capacity is 3x so 1C is now 3,6Ah.

9V is a fair cut-off voltage for discharging.
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Old Jun 29, 2003, 07:48 PM
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Oh..so 1C per Cell then. So I could charge my 2s pack at 2.4V...I was wondering why it was taking so long to charge at 1.2amps.
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Old Jun 30, 2003, 11:01 AM
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Stavanger, Norway
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Ozzieflyer, you're confused

Assume Etec1200's:
If you have 2cells in 2s1p config 1C = 1.2Ah
If you have 4cells in 4s1p config 1C = 1.2Ah
If you have 4cells in 2s2p config 1C = 2.4Ah

The amount if cells in series does not matter in this regard, only the amount of cells in parallell.

If you have 2s1p and charge at 1.2Ah (1C) total charge time will be around 1h45mins because the current ramp down when the pack reach full. Thats the way LiPo needs to be charged.
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Old Jun 30, 2003, 11:09 AM
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Thanks Haldor

Now, how do I treat a new lipoly pack? The same that I would a new NiMH or Nicad pack?

Sloooow charge?
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Old Jun 30, 2003, 11:51 AM
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Charge it at .8a (1200 mAh pack) for the first 1/2 hour, then hit it with 1.2a from then on out.

*edit*

You might find this page informative: http://www.aircraft-world.com/prod_d...ets/lipoly.htm
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Old Jun 30, 2003, 01:56 PM
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Walled Lake, MI, USA
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New lithium cells need no special treatment different from used lithium cells. Simply use the same charger settings whether the cells are new or used.
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