View Full Version : Determining remaining Lipo capacity?


XXXT4me
02-13-2008, 09:50 PM
I am using a 7.4v 4000mah 2 cell 20c Lipo to run a Mamba Max 4600kv. Charging on an Integy 16x307. Balancing with a Blinky. I am very pleased with this setup but I do not know how to determine the remaining capacity of the battery. The charger shows volts and amps only. Is there a way I can tell what I have left in the battery.
Any help would be welcomed.

ta_man
02-14-2008, 12:31 AM
I am using a 7.4v 4000mah 2 cell 20c Lipo to run a Mamba Max 4600kv. Charging on an Integy 16x307. Balancing with a Blinky. I am very pleased with this setup but I do not know how to determine the remaining capacity of the battery. The charger shows volts and amps only. Is there a way I can tell what I have left in the battery.
Any help would be welcomed.
Here's how I did it for one pack.

Charge up the battery, let it rest for an hour and measure the voltage.

Put it on a discharger (be sure the cutoff is set properly for the LiPo) and discharge about 500 mAHr. Let it rest an hour and measure the voltage.

Repeat the discharge/rest/measure cycle until it hits the voltage cutoff. Then you have a table of voltage versus amount discharged. Some simple arithmetic converts it to a table of voltage vs. remaining charge. Now you know.

guver
02-14-2008, 08:54 AM
An open voltage is a good indicator of sod.

4.2 at the top and 3.5-3.7 at the bottom depending upon who you talk to.

100.00% 4.2 8.4
90 4.13 8.26
80 4.06 8.12
70 3.99 7.98
60 3.92 7.84
50 3.85 7.7
40 3.78 7.56
30 3.71 7.42
20 3.64 7.28
10 3.57 7.14
0.00% 3.5 7

XXXT4me
02-14-2008, 01:03 PM
Thanks to both of you for the help