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Old May 11, 2012, 05:46 AM
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Jack
USA, ME, Ellsworth
Joined May 2008
18,096 Posts
What hoppy said on the 3.7V and 80% cutoff! That is great advice.

When I was getting started with LiPOs I found a couple of his posts with the testing info he mentions and started using the 3.7V per cell, as measured under load, for my low voltage cutoffs and ending flights. And I still have nearly every LiPO pack I have ever bought.

Here a summary of his info and links to his posts:

LIPO Capacity @ Voltage per cell (cell voltages, multiply by cell count for pack voltage, i.e. for 3S pack multiply x 3)

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 dumps and damage begins.

Avg Resting V % Remaining Capacity (for 3S pack, divide by 3 for cell voltages)

11.0V-- 17% (3.67V per cell)
11.1 --- 26 (3.70V per cell)
11.2 --- 30 (3.73V per cell)
11.3 --- 37 (3.77V per cell)
11.4 --- 46 (3.80v per cell)
11.5 --- 50 (3.83V per cell)
11.6 --- 57 (3.87V per cell)
11.7 --- 63 (3.90V per cell)
11.8 --- 69 (3.93V per cell)
11.9 --- 77 (3.97V per cell)
12.0 --- 83 (4.00V per cell)

These values are the average of many discharges of different size/age/brand packs. As you can see, the values are not absolute. A new pack gives different results from a well used pack but the chart is still useful for the broad picture.

Thanks again, hoppy!

Jack
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