Testing different LiPos

Discussions and questions about the Crazyflie Nano Quadcopter
derf
Expert
Posts: 161
Joined: Fri May 31, 2013 12:17 am
Location: Germany

Testing different LiPos

Post by 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
Bitcraze
Posts: 1541
Joined: Mon Jan 28, 2013 7:17 pm
Location: Sweden

Re: Testing different LiPos

Post by 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
Expert
Posts: 161
Joined: Fri May 31, 2013 12:17 am
Location: Germany

Re: Testing different LiPos

Post by 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
Expert
Posts: 161
Joined: Fri May 31, 2013 12:17 am
Location: Germany

Re: Testing different LiPos

Post by 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
Bitcraze
Posts: 1541
Joined: Mon Jan 28, 2013 7:17 pm
Location: Sweden

Re: Testing different LiPos

Post by 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.

theseankelly
Expert
Posts: 143
Joined: Mon Dec 28, 2015 3:23 pm
Contact:

Re: Testing different LiPos

Post by theseankelly » Fri Apr 07, 2017 4:29 am

I recently bought a batch of these and they work very well! Good throttle response and discharge rates.

https://hobbyking.com/en_us/turnigy-nan ... tible.html
http://www.thejumperwire.com
Tips, tutorials, and science about DIY electronics, drones, and embedded software.

hittstick
Beginner
Posts: 26
Joined: Thu Apr 06, 2017 7:26 am

Re: Testing different LiPos

Post by hittstick » Thu May 04, 2017 2:11 pm

I was thinking about picking some of these up, but now I'm leaning towards @theseankelly's suggestion:
https//www.amazon.com/gp/aw/d/B01DK7TIOS/ref=o ... KYHX&psc=1

theseankelly
Expert
Posts: 143
Joined: Mon Dec 28, 2015 3:23 pm
Contact:

Re: Testing different LiPos

Post by theseankelly » Thu May 04, 2017 2:29 pm

5 batteries for 12 bucks is probably too good to be true... I did the same thing twice (not that exact listing -- two separate ones actually). The first worked reasonably well but by 6 months all were dead (actually, one was DoA..swelled up after first use). Could have been poor discharge habits on my part (I think I was running them down a bit too much before I knew anything about lipo care) but 6 months is a really short life span. I ordered again what looked to be the same battery, different listing -- they had very very poor discharge/throttle response so the copter wasn't responsive at all. Decided to go with the ones I posted since turnigy is a pretty respected name in batteries. So far I'm thrilled with their performance, but of course haven't had them long enough to comment on overall lifespan.
http://www.thejumperwire.com
Tips, tutorials, and science about DIY electronics, drones, and embedded software.

theseankelly
Expert
Posts: 143
Joined: Mon Dec 28, 2015 3:23 pm
Contact:

Re: Testing different LiPos

Post by theseankelly » Mon Jun 12, 2017 2:01 pm

Uh oh. The weather has gotten nicer and I've gotten outside to do some pretty aggressive FPV/acro flying on my crazyflie -- turns out I don't think I can recommend these batteries anymore. The voltage sag is pretty extreme under full throttle with my 25mW cam/vtx strapped on top, and the copter can't really recover from freefalls of any length.

I picked up a handful of these, originally mentioned by Fred (NOTE: The leads are reversed! You must cut the heat shrink and reverse the leads in the molex connector - and be careful not to let the bare leads touch :D) and I'm much happier so far. They don't necessarily provide any more power, but they seem to respond to bursts of throttle faster. Might have to do with that almost 2x 'c' rating. I'm hoping to do a deeper study into the differences between these LiPos someday soon.

At any rate, I think the original ones I recommended are okay for simple indoor self-leveled flying, but if you want to start doing FPV acrobatics you'll need a better LiPo.

Edit: Oh, and the weights on hobbyking appear to be BS. Both of the batteries I've spoken about weigh in at 9g on my scale.
http://www.thejumperwire.com
Tips, tutorials, and science about DIY electronics, drones, and embedded software.

tobias
Bitcraze
Posts: 1541
Joined: Mon Jan 28, 2013 7:17 pm
Location: Sweden

Re: Testing different LiPos

Post by tobias » Tue Jun 13, 2017 9:28 am

Thanks Shean, great to get feedback about batteries. It was a long time I tested and it would be great to know if there is any updated to the technology.

To get low resistance for FPV flight you need batteries without a PCM (protection circuit), which limits the peak current, but adds a bit of risk. If you know what you are doing I don't see any problems with it though.

How did that battery fit mechanically?

Post Reply