I have got an quadcopter kit from aliExpress.It had 4 BLDC Motors rated at 6.5A(max).I am about buy an 2200mAh (3S) Li-Po battery.What flight time can I expect with this setup?

4 x 6.5A = 26A. 2200mA means in theory it can deliver 2200mA (or 2.2A) for one hour or 22A for 1/10th of an hour.

So if you run at full power all the time you use more than 22A so you’ll get less than 1/10th of an hour. And you don’t want to completely empty the battery so you’ll get even less. But then you probably won’t run at full power all the time so that might give you a bit more time.

And all that is just a long winded way to say “No-one knows. All you can do is guess”. It could be 5 or 6 minutes or almost anything between about 3 minutes and 10 minutes. Or it could be badly set up or too heavy and so not fly at all.

Steve

slipstick:
4 x 6.5A = 26A. 2200mA means in theory it can deliver 2200mA (or 2.2A) for one hour or 22A for 1/10th of an hour.

So if you run at full power all the time you use more than 22A so you'll get less than 1/10th of an hour. And you don't want to completely empty the battery so you'll get even less. But then you probably won't run at full power all the time so that might give you a bit more time.

And all that is just a long winded way to say "No-one knows. All you can do is guess". It could be 5 or 6 minutes or almost anything between about 3 minutes and 10 minutes. Or it could be badly set up or too heavy and so not fly at all.

Steve

What battery capacity would you recommend for getting atleast 10 Mins of flight time regardless of the power used?

If you want “at least 10 minutes” when you might be using full power all the time you can work it out yourself.

Full power is 26A. 26A times 10 minutes = 260 Amp.minutes. There are 60 minutes in an hour. So do the division. That gives you an answer in Ah (Amp.hours). If you want the answer in mAh multiply by 1000 because there are 1000 mA in one A.

So what do you think you need?

Steve

"If I put ten litres of fuel in my car, how far can I go? My car has a 160 PS engine"

To estimate endurance at all well we'd need a full mass budget for the craft, the performance
curves for the precise motor/prop combination, some estimate of the ESC efficiency/losses.

One important detail is sizing the motors right, so that they don't overheat, but aren't any heavier
than necessary... A lot of the weight is in the motors so this is the first place start optimizing
once the overall mass budget is sketched out.

performance (basically connect a sensitive balance or force sensor to a tethered motor/prop and
plot thrust against ESC input voltage & current). You can also check up on motor temperature
rise fairly easily this way.

An easier approach is find out viable setups others have used for the same mass craft.

shyam_electroid:
What battery capacity would you recommend for getting atleast 10 Mins of flight time regardless of the power used?