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-   -   Lipo cell question (https://www.rc-monster.com/forum/showthread.php?t=29840)

candy76man 04.18.2011 10:19 PM

Lipo cell question
 
I have a couple 3s 2200mah 30c lipos I don't use for anything. I have a heli that runs on 2s lipos so I took one of the 3s packs apart and made a 2s pack out of it to test.
My question comes up because I get less runtime on the pack I made than I do on the 1200mah 2s packs I bought for the heli.

Based on the specs of the battery I took apart what is the mah and c rating of the individual cells in it? I thought each cell would be 2200mah and 30c but I'm obviously confused since I should get near double the run time (over the 1200mah pack) if my assumption were correct.

Thanks!

Arct1k 04.18.2011 10:25 PM

You are correct but they could be duff cells

What's_nitro? 04.18.2011 10:32 PM

How long were you not using them for anything? The cells probably lost capacity from sitting on the shelf too long.

candy76man 04.18.2011 11:13 PM

hmm, I have had them about two years at storage voltage (3.8 volts)which is what they still had when I checked before disassembling them. They were still balanced and charge to 4.2 volts apiece?
I bought them before I knew much about lipos to use in my erevo but found out they wouldn't supply enough amps to run it safely before they got to me so I never used them.

Before I realized I needed to cut the wires off before desoldering the tabs (wires were sucking all the heat away) I got two of the cells a little warm to the touch near the top from keeping the iron on the tab too long...could that have damaged them? They were warm, not hot. All the cells casings are still tight, no puffing at all.

candy76man 04.18.2011 11:25 PM

Do you think after cycling them a few times they might start coming back to life and hold a charge longer or are lipos done for once they get like that?

Bondonutz 04.18.2011 11:25 PM

Sometimes the cells just loose performance without showing any obvious signs.

I had a couple of PolyQuest packs that were 4500mah 4s 30C that just slowly faded to nothing. Even tho they balanced near perfect, thay had lost capacity and power without puffing.

Storing them for 2 years at 3.8 certainly didn't help, kinda surprised they worked as well as they did for you.

Quote:

Originally Posted by candy76man (Post 404701)
Do you think after cycling them a few times they might start coming back to life and hold a charge longer or are lipos done for once they get like that?

Wouldn't hurt to try but don't hold your breath.


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