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Sep 13, 2014, 12:58 PM
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Lipoly Voltage vs. State-Of-Charge (Remaining Capacity)


The question of 'how much capacity is remaining in my lipo batteries' comes up quite frequently. Several have characterized the discharge characteristics of a lipoly cell and determined that resting voltage is a very reliable indicator of remaining capacity. These results have been posted in RCGroups several times over the years.

I performed some characterization tests last year on a modern lipoly and have corroborated my test results with similar testing performed by John Julian who achieved nearly identical data. I've posted this data several times and some have found it helpful.

One of my friends recently asked me to whip up a quick reference spreadsheet for 2S to 6S packs that he could print out, laminate, and stick inside his field box. I obliged and he found it to be very helpful in quickly calculating optimum flight times for his models. I've posted them below in .jpg and .pdf formats.

The charts are pretty self-explanatory. Simply measure pack resting voltage (no load, out of model) and then compare voltage with the far left column to get a solid idea of state-of-charge (available capacity). I added some color coding to denote the regions that become unhealthy for lipoly longevity. The yellow is a caution zone and the red coding is where one is risking a damaged pack or model.

Enjoy!

Mark
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Sep 17, 2014, 11:02 AM
who dares wins
like2fly!'s Avatar
Thanks, that's handy.

Regarding the Revo 70C 4.27v Lipo's.

Would you know the remaining capacity of those at 4.2v?
Sep 17, 2014, 02:07 PM
Space Coast USA
hoppy's Avatar
Based on this data about 95%.

Send a PM to REVOJohn and ask him, he's on this forum.
Sep 17, 2014, 04:22 PM
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like2fly!'s Avatar
Quote:
Originally Posted by hoppy
Based on this data about 95%.

Send a PM to REVOJohn and ask him, he's on this forum.
Thanks for the link. An interesting read. I'll ask John at Revo, cheers.
Sep 17, 2014, 04:27 PM
Registered User
Thread OP
I think John Julian has done some testing on the 4.27V Revos but don't know whether he's performed this level of characterization. Perhaps he will chime in.
Sep 18, 2014, 04:21 AM
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like2fly!'s Avatar
REVOJohn replied to my PM stating 4.2V = 92% of the rated capacity of the battery for the 427 blend
Feb 15, 2016, 05:53 PM
Registered User
Mrforysh
Very good seeing that my battery checker displays one cell at time. I usually have a reading of 3.78 to 3.76 per cell, I guess I am right against the wall now. Thank you that is a very good graph and good info.
I will leave this open somebody may have other commits to make.

Ken


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