A little confusion with my first ever quadcopter build.Please Help!

[3XTR3M3]

Hi,
This is my first ever thread on this forum and I am a complete beginner when it comes to quadcopters or drones.I have been interested in them for quite some time now but never had a chance to build my own until NOW!!

So I am building my first ever quad and it is an FPV Racer.I know a lot of you will say that an FPV is not for beginner,your first drone should be a regular one but I have made up my mind to build FPV one.I am ordering this kit from EBay.Please have a look at it and suggest or comment on my choice.This it contains everything from Radio to FPV system, 12 amps ESCs and 2400 kv motors and everything else.The only thing it doesn't contains is a battery.Please have a look at the kit first:

http://www.ebay.com/itm/161803894134

I have already researched and understood some basic and advanced concepts about quads and I know everything about the C rating and mAh value etc etc.So the battery I chose is 1300 mAh and 3S with 30C capacity and 60C burst mode.Now I know that:

12 Amp ESCs with 14 Amp max that they can draw for 10 sec.But the battery burst mode sends out 1.3 A x 60C = 78 Amps while the max Amps all the ESCs can take is 14 x 4 = 56 Amps.

I want to know that will this battery fry the ESCs? According to me it looks as if it will but will other components such as Flight controller and Video Transmitter come into play thus the current will be drawn to them too?

Here is the link to the battery:

http://www.ebay.com/itm/251860276868

And one more question:

What is the average flight time of an FPV racer? I heard it is 5-6 Min which is according to me pretty low but I'm no expert and a complete noob in this matter so please guide.

 

[fengshuidrone]

That battery is made for what you want. The battery only stores the electricity. It doesn't work the way you describe. The ESCs will draw the amps they need to operate. The battery has no "say so" in what amps are required by the motors and ESCs. It will not force any amount of electricity through your circuits that is not drawn out by those circuits. The fact that your battery is capable of 78 amps during burst just means that it is plenty enough for your circuit which is only pulling 56 amps at burst. It is actually maybe just a little overkill though when you might be able to save weight with a lower C rating that more closely matches your circuit. Or you could up the MAH and lower the C a little at the same weight. The flight Controller will get it's power at less than full voltage (battery, 11.1v.....FC, 5v) from the BEC on one of your ESCs unless you plan on buying a UBEC to supply the voltage, and your video transmitter the same thing. Your video TX will most likely take a 5v lead off of your flight controller on a spare + pin. Those two things being hooked up will only drain your quads battery a tiny bit and you HAVE to have the FC powered so that doesn't even count as extra draw. The more "accessories" you have running off of your battery, the shorter your flight times will be, but you don't have to worry about that battery killing your ESCs. Your flight time will mostly be determined by your mah rating but only to a point when battery weight becomes a limiting factor.

 

[3XTR3M3]

That battery is made for what you want. The battery only stores the electricity. It doesn't work the way you describe. The ESCs will draw the amps they need to operate. The battery has no "say so" in what amps are required by the motors and ESCs. It will not force any amount of electricity through your circuits that is not drawn out by those circuits. The fact that your battery is capable of 78 amps during burst just means that it is plenty enough for your circuit which is only pulling 56 amps at burst. It is actually maybe just a little overkill though when you might be able to save weight with a lower C rating that more closely matches your circuit. Or you could up the MAH and lower the C a little at the same weight. The flight Controller will get it's power at less than full voltage (battery, 11.1v.....FC, 5v) from the BEC on one of your ESCs unless you plan on buying a UBEC to supply the voltage, and your video transmitter the same thing. Your video TX will most likely take a 5v lead off of your flight controller on a spare + pin. Those two things being hooked up will only drain your quads battery a tiny bit and you HAVE to have the FC powered so that doesn't even count as extra draw. The more "accessories" you have running off of your battery, the shorter your flight times will be, but you don't have to worry about that battery killing your ESCs. Your flight time will mostly be determined by your mah rating but only to a point when battery weight becomes a limiting factor.

Hmm, Thank you very much it was very helpful.So the basic idea is that you need a specific battery not because it will affect the components but because of the weight.You can add as high rated battery as you want but it will add more weight.Is that true?I have the concept now.Thank you very much sir.Can you please visit the battery link and see it and tell me if it is ok compared to my kit.This is my first build so im a little shaky and it will take long time to ship where I live so I don't want to order something else afterwards.

Regards.

 

[fengshuidrone]

"So the basic idea is that you need a specific battery not because it will affect the components but because of the weight.You can add as high rated battery as you want but it will add more weight.Is that true?"

Yes that is the gist of it.

"Can you please visit the battery link and see it and tell me if it is ok compared to my kit."

All I can say is that yes, it will make your quad fly. You should go use one of those online battery calcs to see if it will do for what you have in mind. It's weight at 100 grams is light enough. I do not do any FPV racing so you might want to get the opinion of someone who does that to find out if your battery is suitable as far as mah rating and stuff like that. I'm sure that there is a racer on this forum who can help out.

 

[3XTR3M3]

"So the basic idea is that you need a specific battery not because it will affect the components but because of the weight.You can add as high rated battery as you want but it will add more weight.Is that true?"

Yes that is the gist of it.

"Can you please visit the battery link and see it and tell me if it is ok compared to my kit."

All I can say is that yes, it will make your quad fly. You should go use one of those online battery calcs to see if it will do for what you have in mind. It's weight at 100 grams is light enough. I do not do any FPV racing so you might want to get the opinion of someone who does that to find out if your battery is suitable as far as mah rating and stuff like that. I'm sure that there is a racer on this forum who can help out.

So I decided to change the battery to a higher mAh one.Now I am buying a 1500 mAh one.It's weight is a little bit more 120g instead of 100g but hopefully i will get a longer fly time.I have tried to calculate flight time using different online calculators.I put in the max current draw by motors and it gives me 2-3 mins of fly time but i know this is not actual because the motors will not draw max current at all time.Also calculating flight time first hand is very complicated at least for me because it involves calculating total weight of the quad and also the amp draw by motors or ESCs or both.So I am going to order all the parts finally and I have changed the battery to 1500 mAh one with same specs as before.

 

[Webheadfred]

It's been a while since I've posted but here is my 2 cents. Your motor and prop will "draw" the amount of current they need from the battery. Too small mah, there won't be enough for what's required. There's really no such thing as too large unless weight becomes a factor. The one thing I learned is to use good wiring.

Many failures come from the motors drawing too much current. Cheap wire will deliver it; however, it can get very hot; to the point where the insulation melts causing catrostrophic failure. A high quality wire can deliver higher amps for a given gauge as the insulation is silicone and a much higher melting temperature.

The cool thing about building is that you learn so much. Too small rating of the motor controller can lead to the same thing. Everything is so interrelated. Higher pitch props, bite more air, causing motor to work harder, drawing more amps, and doing more work and lifting more. Lower pitch props, may actually give you a better feel, take less energy and less vibration. Your motor speed per volt may not be enough and different motors would be needed but it would draw less current. It's trial and error and learn and repeat. Mainly, the satisfaction of finally getting your baby in the air is a huge success. I still have the video of my first flight. My small quad made from Home Depot aluminum towel rods and a plastic frame I had laser cut from some online supplier from a design I did in Adobe Illustrator. Fun stuff. I had no idea what I was doing and it was fantastic! Now 10 or so multi rotors later, I'm still tweaking and learning. And there I go rambling... Have fun.

 

[Webheadfred]

Oh yes... On my first big Coaxial 8, I planned for 150 amp draw. 8 gauge silicone wire. 50c battery. Really heavy. I over estimated by a lot. I put a flying amp meter on and discovered my maximum draw on the system was a mere 60 amps. Oh well, live and learn.