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Old 07-29-2006, 11:43 PM
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Namuna Namuna is offline
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Li-Poly Q&A

(to make it easier to find this thread: Lithium Polymer, Lipo, Li-Po, Li-Poly).

I've recently decided that I want to jump into the LiPo fray and am now starting to order all the pieces. Just yesterday I ordered the Duratrax ICE charger and now I'm looking to buy Cells for my cars (Bits/ZipZaps, Epoch, Xmods/MiniZ and my M18).

It seems that the more I read about LiPos, the more precautionary steps I need to take (as compared to NiMH packs) So I thought I'd start this thread in the hopes of having the folks that know their stuff come in and answer some questions I have (and that anyone else has) in one place.

Here we go...

1. Supposedly it is VERY BAD to run my LiPo cells below a certain voltage. What are those voltages for a single pack, 2s pack, 3s pack, etc...

1a. Knowing that running down a pack too low is bad, do I need to get some kind of voltage cut-off device for my ESC (I have the Novak Spy in my M18)? If so, can you recommend one?

2. Can rechargable Lithiums (Ion and Polymer) be charged on the same charger...If that charger only stated it did Lipo? Such as the Apache 2020/2030/2500 chargers that only specify being able to charge Lipo.

3. I heard a little about buying modules for your Peak Charger for balancing LiPo packs? Is this something I need?

4. With NiMH batts, charging at over 1C isn't unheard of...Is it okay to charge at higher than 1C (assuming that I keep a close eye on temperature)?

That's all the questions I have for the moment, I'm sure I'll think of some more and post them...If you have any questions please feel free to post them and if you have any answers PLEASE definitely post! :-)

Thanks!
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Old 07-30-2006, 02:54 AM
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Roelof Roelof is offline
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1. The limit is about 3.1v per cel (normally a cell is 3.6 or 3.7 volt)

1a. you can also use a Lipo monitor, it is a simple device which will light a LED when the voltage becomes under the voltage.

2. Tricky... Li-Ion are rated 3.6v per cell and LiPo 3.7v, you could overcharge them but is unlikely with 0.1v per cell

3. there are LiPo balancers, they work like discharge tray's for NiCad/NiMha packs if you have a balance connector on the pack. It will take away the difference between the cells after some charge cycles and makes the risk of exploding cells less.

4. With NiMha 2C charging is normal rated, with Lipo it is normally 1C but some experiments with quality chargers show 1.5C is working fine.
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