Battery Advice

Hi, I am new to this forum and the RC game. I am building a paramotor and using the parafoil sold by Hobby king. I have selected a motor based on the advice given her in the forum and a suitable ESC. My question and confusion is regarding the battery. From what I read and understand I need at least a 4s 70C rated cell which are a lot of money and limited available. With the spec of the motor below am I calculating this correct and do you recommend a particular battery?

Specs:
Model: NTM Prop Drive Series 3548 900kv
Kv: 900rpm/v
Poles: 3
Motor Wind: 7T
Max current: 55A
Max Power: 570W @ 12v (3S) / 815W @ 15v (4S)
Shaft: 5mm
Weight: 171g
ESC: 60A
Cell count: 3s~4s Lipoly
Bolt holes: 18.9mm & 25mm
Bolt thread: M3
Connection: 3.5mm Bullet-connector

Many thanks in advance.

According to the notes on the parafoil "A typical power system is a 35-30 size motor with a 2200mAh 3S battery."

Why do you need such a high C rating? That's only really used for power bursts (wide open throttle)


To calculate or understand a "C rating" you first need to convert the battery capacity from milliamps (mah) to amps which is really simple, you just at a decimal point. So it goes like this... a 5000mah battery is 5 amps, a 4600mah battery is 4.6 amps, a 4200mah battery is 4.2A... and so on. The amp number you just got is a "C"... so for a 5000mah battery, 1C = 5A.

Now the "C rating" is the "C-number" multiplied by the amperage. So using our 5000mah example again... if it has a 25C rating with a 40C burst, it means that the battery can safely put out 125A (25 x 5A = 125A) of power continuous (25C) and 200A burst (40C) - burst meaning a quick 5 to 10second surge of power like accelerating from a dead stop.

This goes for charging also. What they mean by saying you can charge your battery at 2C means you can charge at twice the capacity. So for a 5000mah battery, you can safely charge at 10A.

I've been reading into this further, I think I get it now. If I choose a 3300mAh 4S 30C Lipoly Battery then using (C-Rating)x(Ah)= Max Constant Draw then 3.3 x 30 = 99. I can easily run a Max output on my motor of 55A and using the 4S then I get my 15v. Am I right in my thinking?

One last thing I'm trying to understand is the power consumption, i.e. how long will it last before it falls out the sky?