Electronic – Lipo battery specs

batteries

I'm starting a project of modeling a quadcopter. For this I'm of course in need of a battery and I have red a bunch of threads to understand how to read the specifications of them.
The most complete website I found was the battery university. http://batteryuniversity.com/learn/article/what_is_the_c_rate

I still have a question about the C-Rate.
For exemple this battery: http://www.hobbyking.com/hobbyking/store/__8932__Turnigy_2200mAh_3S_20C_Lipo_Pack.html

Spec.
Minimum Capacity: 2200mAh (True 100% Capacity)
Configuration: 3S1P / 11.1v / 3Cell
Constant Discharge: 20C
Peak Discharge (10sec): 30C
Pack Weight: 188g
Pack Size: 103 x 33 x 24mm
Charge Plug: JST-XH
Discharge Plug: XT60

If i understood well, since the constant discharge is 20c, (so 20*2200 =44 A) this battery will have a good flytime if my motors are pumping less then the 44A? (more than 100%)

Thanks!

Best Answer

To first order, if the capacity is actually 2.2Ah ...

You would get nominally 3 minutes fly time at 44A = 20C.
You would get nominally 6 minutes fly time at 22A = 10C.
You would get nominally 12 minutes fly time at 11A = 5C.

Nowhere does the battery capacity exceed 100%.

A lower rate does trivially allow you more than 100% of the 20C fly time.

The actual capacity you get, and the discharge rate, are inversely linked. Not as strongly as the reciprocal, but you need to check what the capacity is at your discharge rate.

Unfortunately, the capacity is usually quoted at the 1C rate, for a 1 hour discharge. The capacity at 20C will therefore before lower than 2.2Ah. How much lower? This depends to some extent on the quality of the battery. This means that the nominal flight times above are really 'will not be exceeded' times.