Testing different LiPos

Discussions and questions about the Crazyflie Nano Quadcopter
theseankelly
Expert
Posts: 128
Joined: Mon Dec 28, 2015 3:23 pm

Re: Testing different LiPos

Postby theseankelly » Tue Jun 13, 2017 2:35 pm

Yeah definitely need to be careful. I have a pretty conservative voltage alarm ( <= 3.4v ) set up on my Devo, and use a proper lipo charger to charge. Do you know what the internal resistance of the stock battery is? I have a lipo charger that claims to measure internal resistance, though I have not done my own test to check its accuracy. On that charger, it says the stock battery is about 300 mOhms (though, I've run that battery into the ground so I expect it would be lower brand new). The 20C 300mah battery reads in at about 120 mOhms (flown through maybe 10 cycles by now), and the 45C 300mah battery is about 80mOhms (basically new - 1 or 2 flights). I definitely see these differences reflected in the effective voltage sag under load, which explains the difference in performance.

Mechanically, they're all good. The 20C are a little bit thicker and a little bit narrower than the stock battery. The 45C are a little bit longer than the stock battery but otherwise the same. Both fit between the headers and I haven't had any problems with them falling out while flying using the friction method (the foam pad + battery holder deck) but I'm going to add some Velcro or dual-lock to be safe.



tobias
Bitcraze
Posts: 1483
Joined: Mon Jan 28, 2013 7:17 pm
Location: Sweden

Re: Testing different LiPos

Postby tobias » Wed Jun 14, 2017 8:25 am

I'm not sure the internal resistance of the stock battery but 300mOhm sounds a bit much, would have expected 150-200mOhm but as I haven't tested it accurately I can't tell if it is correct or not. Which charger do you have? Do you know what method the charger use to measure it?

hittstick
Beginner
Posts: 23
Joined: Thu Apr 06, 2017 7:26 am

Re: Testing different LiPos

Postby hittstick » Thu Jun 22, 2017 3:35 am

I picked up a 6-pack of Tattu 380mah 3.7V 1.4Wh lipos and they're working great. Size is a bit longer than the stock battery for the CF2, but they work great, give a couple extra minutes of flight time.


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