What battery for 450 quad with gimbal?

[ageorge]

Hey guys i have a 450 quad with sunnysky 2212 980kv motors 30a escs and a dji naza.I also have a modded runcam and a 2axis gimbal that i would like to add.The 2 axis gimbal weighs around 180 grams.I want to get around 8-10 minutes of flight time and more would be better.Right now i have a 2250 mah battery 3s will this be enough?I have tried various calculators but get very different results.The maximum i can afford for the battery is around 30 dollars.Dont want anything heavy.My eyes are on this at the moment https://hobbyking.com/en_us/multist...ah-multi-rotor-lipo-pack-for-qr-x350-pro.html or https://hobbyking.com/en_us/zippy-flightmax-5000mah-3s1p-20c.html

 

[megabotz]

What is your all up weight, not counting your battery?

Your motor spec sheet will tell you their thrust capability in grams. Take the value at around 50% & multiply that by the amount of motors you have. This value will tell you at what weight the craft will comfortably hover at 50% power.

Take your current all up weight, not counting your battery, subtract that from your "hover" value & that will give you the weight of your battery. Pick the highest capacity that doesn't exceed your allowable battery weight & you are good to go.

Of course, if you subtract the all up weight from the hover value & you have a low or negative number, it means your motors are under-powered and/or you need to lighten your load (i.e. no gimbal, etc).

Is there anything preventing you from going 4S? You get greater efficiency at higher voltages.

As far as flight time, you will get the best flight times with the greatest capacity battery that doesn't weigh the craft down further than your motors can comfortably handle. Get this by picking the right motor/prop combo to generate the desired thrust, in addition to picking the lightest materials to handle the loads & achieve your goals.

megabotz

 

[ageorge]

my motors can lift about 475 grams at 50% throttle so that times 4 is 1900 grams of thrust. However do i need to divide this by 2? if so then it is 950 grams.But with my gimbal installed it will probably be near impossible to do 960 grams with the gimbal ,battery and the others..If i dont need to divide it by two guess im good to go.

 

[megabotz]

No need to divide by 2 here if you are using the 50% value. 1,900g is your target weight.

Get yourself a cheap digital kitchen scale. If you aren't completely assembled, throw all the parts & hardware on the scale. 1.2kg without a battery sounds like a pretty heavy estimate so you might be able to add a really big battery.

Your build sounds good so far but you will know more when you get all weighed up.

megabotz

 

[ageorge]

oh ok thanks.Just checked and my motors all together produce 1700 grams of thrust at 50% and 4 .3 kg at 100% At 50% throttle the motors take in around 17 amps so my battery needs to be above 1700 mah right? Thanks for all the help

 

[ageorge]

esc*4-80grams
Motors*4-253 grams
Naza lite-100 grams?
Runcam in gopro case- 70 grams
Gimbal-120 grams
Reciever-20 grams
Frame 250 grams
Wires 50 grams
Screws-50 grams
malicious-50 grams

Total estimate-1043 grams without battery ) so 1700-1043=657 gram battery..

 

[megabotz]

Amps drawn & battery capacity aren't related like that. If you can get a 4,000mAh battery that is the right weight, get that.

There is also the C rating to consider, which is what I think you were trying to calculate. Post the amps drawn at 100% & I will help you calculate that.

A 1,700mAh, off the top of my head, would give you a max of 6 minutes flight time & you wouldn't want to run it that long. Bad for the battery.

Look at my earlier post. Your battery capacity (mAh) has everything to do with what weight you can carry.

megabotz

 

[ageorge]

62.8amps for all motors combined.Plus one for other items like naza etc so 63.8

 

[ageorge]

i can get a 4000 mah 3s 25c for 26 dollars.It is a zippy

 

[megabotz]

That is quite a big battery. You can get a 6000mAh 3S & still have many grams to spare.

You are gonna get better than your desired 8-10 minute flight time.

megabotz

 

[ageorge]

oh ok so is 6000 mah recomended or is it a minimum?Because my budget only allows a 4000 mah.

 

[ageorge]

i can try get a 5500 mah 3s 45c for 32 dollars it is a wild scorpion battery il ask my parents and hope for the best.

 

[megabotz]

You probably want a bunch of power. I personally would do no less than 30C but since you have the weight to spare, you can probably do 50C+.

Just make sure the weight is good.

megabotz

 

[megabotz]

That battery sounds good. Post the video!

megabotz

 

[ageorge]

ok sure the moment i fly it i will

 

[megabotz]

A 4000mAh battery will work, btw. It's just that the higher capacity will allow you to fly longer.

megabotz

 

[ageorge]

oh ok thanks mr Megabotz

 

[ageorge]

il try order one fro hobbyking a 6000 mah 10c or a 5500 mah or a 4000 whichever is cheaper.Thanks for all the help you have really been my mentor in this hobby thanks.

 

[ageorge]

Hello mr megabotz in a recent thread you had stated "ageorge, throw out what I said about the motors. The value you gave looks to be the thrust at full throttle. They won't lift your rig well, if at all."Hello Mr Megabotz are the motors you were reffering to the sunnysky ones in this setup?I double checked and the thrust factors i had given you were for half throttle.Or are the motors you are talking about the old racerstar ones i had in my old forum post?? Thanks here is the link to the video i got the values for the sunnysky motors https://www.youtube.com/watch?v=VuupNMUhSz4 the table is at the end

 

[ageorge]

i plan on using the gemfan 10.45 props and those give around 410 grams of thrust per motor so 410*4=1640 g at half throttle.I could get 470 g per motor if i used 4s so that would be 470*4 =1880 g at half throttle