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Old Feb 04, 2005, 12:39 PM
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MKII = 80% of 4.2v per cell charge

Darrell_F,

I tested two different MKII chargers and the results were the same, 80% capacity of a 4.20v per cell charge.
If you fly to a higher cutoff voltage and use less of the total pack capacity, percentage of charge for the MKII would be less not more.

The MKII is a nice safe charger for Lipo, but unless there was a revision change(?) it can’t charge a 3-cell pack to 12.4v because it terminates the charge at a lithium-ion safe 4.1v per cell or 12.3v.

This is a test I did for capacity vs. Resting voltage.

72 degree pack and room temp.
The (999mAh) pack was discharged each time at 1C, to a 3v per cell cutoff.
Then I added a fixed percentage of charge, and measured the resting voltage after 12 hours.
Next I discharged the pack and verified the percentage of capacity.
At the end of all testing I charged the pack fully and did a accuracy / repeatability test.
The repeatability of the test was over 98%.

4.20v = 100%
4.03v = 76%
3.86v = 52%
3.83v = 42%
3.79v = 30%
3.70v = 11%
3.6?v = 0%

Capacity below 3.7v "resting" is not usable for flying, it's where the battery voltage dump begins.

Jim

<EDIT>
Recent Capacity@Voltage graphs (testing new packs), are located here.
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Last edited by IA-Flyer; Jul 13, 2005 at 09:17 PM.
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