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charge voltage - 2 cell 2200 mah lipo

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Old 01-01-2011, 02:26 PM
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sheko_2000
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Default charge voltage - 2 cell 2200 mah lipo

hello,
i am totally new with lipos
i got myself a 2 cell pack with 2200 amps

the current charge capacity was 7.4 volts for the 2 cells, but i wondered when some one in the field told me that this means that the battery is not fully charged and you have to charge it on 8.4 volts
so i did it as he recommended
but i didnt got the chance to ask him about more details
can any one pls help me with more details as i dont understand how 7.4 volts pack must be charged at 8.4 volts !!
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Old 01-01-2011, 03:57 PM
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Default RE: charge voltage - 2 cell 2200 mah lipo

Most lipos are as follows for voltage vs. charge level:

3.5 per cell = 0%
4.2 per cell = 100%
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Old 01-01-2011, 04:15 PM
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Default RE: charge voltage - 2 cell 2200 mah lipo

thx for the reply
but i am wondring how the 100% capacty voltage is calculated?

and how it will be in case of more cells
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Old 01-01-2011, 08:08 PM
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Default RE: charge voltage - 2 cell 2200 mah lipo

Multiply 4.2 by the number of (series) cells. Your 2 cell is 8.4 volts at 100%
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Old 01-01-2011, 08:30 PM
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Default RE: charge voltage - 2 cell 2200 mah lipo

A lipo will have a nominal voltage of 3.7v. So, that's why a 2s pack is rated for 7.4v. However, when you charge lipos, they are "peaked" (it's actually not peaked, but good enough term for this topic) to 4.2v per cell, which gives you the 8.4v rating for a 2s pack. That 4.2v won't stay there very long when running though; after a minute or so, the voltage will drop closer to the nominal value. All lipo chargers will charge the cell to 4.2v (unless you mess with the termination voltage setting), so don't worry about getting full capacity.

This is similar to how NiMH's are rated for a nominal 1.2v each, but right off a charger, they are closer to 1.4v per cell.
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Old 01-02-2011, 12:04 AM
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Default RE: charge voltage - 2 cell 2200 mah lipo

thanks guys
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