Testing different LiPos

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derf
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Testing different LiPos

Postby derf » Sun Aug 28, 2016 11:27 pm

Hi,

While browsing the HobbyKing website I stumbled upon some LiPos that could be used with the CF2:

The Turnigy nano-tech 260mAh 1S 35-70C Lipo Pack is quite similar to the original LiPo. Both weigh 8g and have almost the same size. Compared to the original LiPo (which has 240mAh), the Turnigy LiPo has an additional 20mAh (260mAh).
There were no noticeable differences during the first flight. I had no time yet to compare the flight times, but I expect it to be in the range of a few extra seconds.

The Turnigy Graphene 750mAh 1S Lipo Pack weighs 18g and has triple the amount of mAh.
CAUTION: Do NOT connect this LiPo to the CF2 without modification! I almost found out the hard way: The polarity of the connector is flipped! It could seriously damage your CF2.

Fortunately this is easy to fix. You just need to cut the black heat shrink around the connector/cable and use a cutter knife or something similar to press down the little hooks, that hold the cables in the connector casing. Then flip the cables around and put them back into the connector (compare it with the original CF LiPo connector).

Sadly the flight test was disappointment. Even with 100% thrust the CF hardly lifted off more than a few centimeters. This is surprising for me because the total weight with the bigger LiPo is 38g, which is less than the 45g CF FPV mod that flew sluggish but could definitely lift off the ground and fly around. With a discharge rate of 65C Constant/130C Burst compared to the original 15C discharge rate I don't think that is the problem.
If anyone has an idea what I could be missing here, please let me know.

Regards,

Fred


P.S.: While writing this post, I found another potential LiPo replacement:
Turnigy nano-tech 300mah 1S 45~90C Lipo Pack.



tobias
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Re: Testing different LiPos

Postby tobias » Mon Aug 29, 2016 10:58 am

Thanks for sharing Fred!
We have tested those as well and the 260mAh one gives a bit more punch I would say, probably because it does not contain a protection circuit which adds some resistance. Therefore they also need a bit more care so it is wise to unplug the battery when not used for a while.

I'm a bit surprised the 750mAh didn't fly. It is not exactly the same but very similar one we tested in this tweet. We got almost 16min hovering on that battery. We might have increased the max throttle to get it to fly though, can't remember.

derf
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Re: Testing different LiPos

Postby derf » Mon Sep 05, 2016 11:15 pm

Thanks for your reply.
I tried a couple of things to rule out a simple user error, but had no luck. So I think it's really the LiPo that does not give enough power.

derf
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Re: Testing different LiPos

Postby derf » Wed Jan 11, 2017 11:49 pm

It's been a while, but I did some more tests with bigger LiPos.

  • First I tested the Turnigy Graphene 750mAh (mentioned in the first post) with a friends X-Racer copter. => Worked fine.
  • Then I tested one of his 600mAh LiPos with my Crazyflie 2.0. => CF barely lifts off the ground.
  • Tested it with another LiPo (Lipo-750mAh-37V-25C-50C). => Same problem: CF barely lifts off the ground.
So maybe the LiPos are actually fine... what if the Crazyflie itself is the problem!?
Fortunately I own a second Crazyflie 2.0. And indeed, my second Crazyflie flies totally fine with the big LiPo!!

So how can this happen, that one CF 2.0 does not work with bigger LIPos? It's flying fine with the standard LiPo.

tobias
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Re: Testing different LiPos

Postby tobias » Thu Jan 12, 2017 9:51 am

That is strange indeed!
My initial thought is that there is some added resistance for the CF2 that doesn't lift of, maybe the battery connector or wires? It might also be bad props/motors. Coming to thing of the battery compensation which might be a cause as well. Try turning that off.


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