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Old May 21, 2003, 11:40 PM
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Little Rock,AR,USA
Joined Jun 2001
289 Posts
Li-polly charging

My question is what's the difference between li-polly charging and nmh? I race rc cars and have some very good chargers (for cars).They can charge down to .5 of a volt and down to 24mV peek detection on the voltage threshold. Will I be able to use what I have to charge
Li-polly?
Thankx,
Shawn
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Old May 22, 2003, 01:29 AM
EDF Head
Haldor's Avatar
Stavanger, Norway
Joined Feb 2000
7,999 Posts
No you wont be able to do that successfully.
http://www.ezonemag.com/pages/efaq.htm#charger5

The problem is that Lithiums need to be charged in a totally different way than NiCd/NiHm, with different charge termination algorithms etc.
Using anything but a specific Lithium charger will ruin your pack.
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Old May 22, 2003, 02:15 AM
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Little Rock,AR,USA
Joined Jun 2001
289 Posts
Back in the old days of rc car's before peak chargers we would hook up volt meters and peak them ourselves. I was wondering if you could peak lipo cells by temp and volts?
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Old May 22, 2003, 05:39 AM
Senior Moment Member
Virginia Beach, Va.
Joined Jan 2002
1,233 Posts
LiPoly cells "peak" long before the charge is finished.
When the peak voltage (max cell voltage) is reached the charger holds that voltage constant by slowly decreasing the current as the charge progresses. The charger never exceeds the max cell voltage and charging is terminated when current drops to about C/10.

NiCad and NiMh chargers won't hold a constant voltage but keep increasing, watching for it to level off then drop slightly (peak detect) to determine end of charge. There is no way to limit the output voltage to a set level, NiCad/NiMh chargers don't need or have that feature. They are just not designed to provide the constant voltage output Li cells require.

Jimmy
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