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Which battery to use??Need help

TeamGaruda

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I am making a 250mm 3d printed fpv quad. Weighs 600g without battery. Tmotor 2207 2250kv motor used, 4:1 thrust ratio at max. Want flight time of around 7-8 mins. What capacity battery should i use?
 
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rtkDarling

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For those motors you're looking at a 4s, 1300 - 1500 mah, 80c or better. Some good options here:


What you want to avoid is getting a huge battery thinking it will help your flight time, the extra weight makes it zero-sum gain. Lower C rated batteries are cheaper, and may look appealing, but they're not going to work well for you. These big boys are for trucks, so steer clear of these:


What frame are you printing? Got a link?
 
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TeamGaruda

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For those motors you're looking at a 4s, 1300 - 1500 mah, 80c or better. Some good options here:


What you want to avoid is getting a huge battery thinking it will help your flight time, the extra weight makes it zero-sum gain. Lower C rated batteries are cheaper, and may look appealing, but they're not going to work well for you. These big boys are for trucks, so steer clear of these:


What frame are you printing? Got a link?
Thanks a ton for the quick reply!
I was initially planning on 5ah then my brain struck on reducing the weight and i am totally inclined with you suggestion.
I have designed the drone on my own on solidworks. I can share the photos though
 

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rtkDarling

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You can give that frame a try, but I think you're going to get a lot of vibration and it's going to make it difficult to tune and fly. Most people that print frames do it for smaller platforms, like whoops and micros. Once you get to 5inch it's tough to print something stiff enough.

Take a look at this guy for some inspiration, and explore rotorbuilds a little.

Cinewhoop:
 
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TeamGaruda

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Agreed. But this build is for a competition and many other drones will be flying so collisions will be there, almost all parts need to replaceable.

Btw how much time do you think it should take to complete one lap of this course(i am a beginner)? Dimensions of the area is 100X50 ft
 

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rtkDarling

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If the course is that small you'll want a much smaller battery to save weight, or at least figure out how many laps you need to do and size it to that. Keeping it small is going to help as well, I'd go with a three inch propeller and smaller frame and motors because that's a small space.

You need to build your rig and practice practice practice. In real drone racing it's not the fastest rig, or even the fastest lap, it's a consistent pilot that wins races. Part of that consistency is printing a VERY stiff frame

That's maybe a 30 second course, you guys might do it in a minute and a half. You'll see with new pilots that half the line doesn't make it through the first lap (and quite a few don't make the first turn) Go slow, race your own race and try to be consistent.
 
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TeamGaruda

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There are a total of 5 laps to be completed so 8 mins of total flight time. Thats what i have to aim now. If each motor takes 5 amps on average then 20 amps total ie 2600mah of battery.
You have been an absolute blessing for me. I can't thank you enough.
 
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rtkDarling

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Don't go above a 1500 mah, 2600 is going to be too heavy. If you can do 5 laps without crashing, then you can do them faster than 1:30. If you can consistently do 5 laps at 1:30 you'll be going slow enough to use less power. A 2600 is so heavy that you're going to lose time in the corners.
 
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HighTechPauper

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You straight up showed me a drl racer vid. How am i supposed to even compare my lap time with it.
While it is true that Vanover is a great racer, don't underestimate yourself, I bet you will be screaming around the course in short order with a little practice! My money is on you to take this competition, and it is all about the fun of flying @TeamGaruda!
 
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TeamGaruda

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Hehe... Thanks for the kind and supportive words.
Need just one clarification. Worked really hard to bring down weight to 450(w/o battery) using pla, lets say after adding battery(total 800g) my 2207 2400kv motor can produce 430g thrust at 50% throttle drawing 6 amps. Can go upto 1200g at full throttle drawing 36a. What can i assume as my average amp draw per motor.
 

HighTechPauper

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Once in flight it is very easy to maintain momentum with lower throttle, you will use most or your battery changing directions since you will need to blip the throttle to make that change in direction with authority. As RTK said, fly your own race and many will crash out early and leave you to cross the finish line for the win. I don't think you can know how your quad will fly and use up battery until you can test it.
 

rtkDarling

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Why the sad face buddy @rtkDarling?
One day I'll fly lines like that... One day ⚡

You straight up showed me a drl racer vid. How am i supposed to even compare my lap time with it.
It is good to know what the hardware is capable of, that way you know as an engineer that you're overshooting your performance marks. What all this points out is that you can potentially save a lot of weight in craft, battery and motor because as a pilot you aren't experienced enough to channel this much thrust efficiently. Of course it all hinges on how much you have to pick up between every lap.
 
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