Help needed. Why the battery is struggling with 3.8volts left of charge? - Page 2 - RC Groups
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Jan 30, 2013, 08:11 AM
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flypaper 2's Avatar
After a flight, are tha batts warm at all.? They do generate some heat of their own depending on the amp draw/load. If they are coming out cold, you may be able to tape over the compartment just to retain the heat. I make these socks from the thin foam that electronics comes in. Taped together with Scotch tape and a closure held shut with velcro. May have to play with the insulation a bit. Too much may overheat the batt. I like them to come out just warm in my hand.

Last edited by flypaper 2; Jan 30, 2013 at 06:22 PM.
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Jan 30, 2013, 05:20 PM
That's a funny word
Originally Posted by sgrouts
Testing results:
I got my two lipos without charging them after the test flights that I already told you about.
Room temp= 24 C
I connected a lipo checker to the balance port.
I also connected my HK wattmeter that usually measures a top Amperage draw of 55A with lipos fully charged.
Both of the lipos started with 3,85 each cell with some cells at 3,84 and gave at most 25-27A at WOT.
During that WOT the individual cells dropped at 3,55V the minimum. To be honest they were holding at around 3,65 but after a few secs I saw 3,55 at some cells.
So no below 3,30V dropping as I was expecting.
Time to check other things.
I reprogrammed my moxie 80A esc (low pricerc) using my programmer card and changed two settings:
Gas pedal set to high from medium
Model start set to low from high.
Repeat the tests using both lipos:
They both gave almost 45 Amps each!
And without recharging after the problematic flights...
As I said this is a new setup on a new wing that I built.
I have used my esc at the past with 3s lipos on smaller motors,
But now I am using an NTM 42-38 motor with a 14x8 folding prop.
To be honest I do not even know what that esc settings are doing exactly.
Thank you for helping.
I guess all bets are off if the readings weren't taken at actual WOT. I surely don't understand those esc settings , but WOT should be WOT regardless of state of charge , right?
Jan 31, 2013, 05:36 AM
Vote F5J Gracia for FPV
sgrouts's Avatar
Flypaper, thank you for the idea.
Gulio, I can't even guess what those parameters actually do regarding motor control and why they limited the amperage draw from 40+ to 20+.
I asked from lowpricerc a programming card users manual, but they replied there is none. Strange things...
The sure thing is that cold affects lipos so I will implement a way to protect them from high speed cold air flow.
Thank you.


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