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Nate
05-15-2010, 12:36 AM
Hello,

I'm hoping someone can help me to better understand the ratings on ESC's and motors. My background is in computer science & robotics, so I'm used to working with similar devices, but the ratings and designations on hobby class equipment is slightly different than what I'm familiar with. The tutorials have been great in suggesting specific models, but I really need to understand the reasoning behind these choices, so that's why I've come here.

Right now, I'm having trouble with the ratings given to hobby class motors, which I will be using on my quadcopter. For reference, I am interested in building a 'heavy lifter' class copter, as I will be adding an additional board for a camera and LIDAR unit later down the road. I don't expect to tack on too much weight, but I'd rather have the extra lifting ability if I need it. My quadcopter will eventually be working as a team with an autonomous personnel carrier to provide navigation data.

Here is what I need help with:
1) I see motors listed in 'classes' for helicopters and planes. It seems to go from 100 to 600, and I can infer that this relates to the size of the vehicle. I'm not sure how to translate this into my quadcopter, though. I assume that I should ignore the 'class' and focus on the Amperage and KV ratings?

2) For the ESC: should the continuous current output of the ESC be higher than the max amount of current that the motor can draw?

3) Back to the motors, I have seen a multitude of KV ratings. From what I have read it seems that the 1000Kv range is best for quadcopters. Is this correct?

4) What Amp and KV ratings would be a good motor choice for my 'heavy lifter' quadcopter?

Here is the ESC I am considering. Not sure if it will be overkill or not, but the price is great. If I can find decent motors on this same site that would be great too. Otherwise I'll buy from HobbyKing.
http://www.hobbypartz.com/30a-electronic-brushless-esc-speed-controller--volcano-series-.html

I appreciate any answers you can offer as to be questions, and certainly welcome any suggestions with regard to my motor and ESC choices.

Thanks,
Nate

TCIII
05-15-2010, 01:15 AM
Hello,

I'm hoping someone can help me to better understand the ratings on ESC's and motors. My background is in computer science & robotics, so I'm used to working with similar devices, but the ratings and designations on hobby class equipment is slightly different than what I'm familiar with. The tutorials have been great in suggesting specific models, but I really need to understand the reasoning behind these choices, so that's why I've come here.

Right now, I'm having trouble with the ratings given to hobby class motors, which I will be using on my quadcopter. For reference, I am interested in building a 'heavy lifter' class copter, as I will be adding an additional board for a camera and LIDAR unit later down the road. I don't expect to tack on too much weight, but I'd rather have the extra lifting ability if I need it. My quadcopter will eventually be working as a team with an autonomous personnel carrier to provide navigation data.

Here is what I need help with:
1) I see motors listed in 'classes' for helicopters and planes. It seems to go from 100 to 600, and I can infer that this relates to the size of the vehicle. I'm not sure how to translate this into my quadcopter, though. I assume that I should ignore the 'class' and focus on the Amperage and KV ratings?

2) For the ESC: should the continuous current output of the ESC be higher than the max amount of current that the motor can draw?


3) Back to the motors, I have seen a multitude of KV ratings. From what I have read it seems that the 1000Kv range is best for quadcopters. Is this correct?


4) What Amp and KV ratings would be a good motor choice for my 'heavy lifter' quadcopter?

Here is the ESC I am considering. Not sure if it will be overkill or not, but the price is great. If I can find decent motors on this same site that would be great too. Otherwise I'll buy from HobbyKing.
http://www.hobbypartz.com/30a-electronic-brushless-esc-speed-controller--volcano-series-.html

I appreciate any answers you can offer as to be questions, and certainly welcome any suggestions with regard to my motor and ESC choices.

Thanks,
Nate

Nate,

2) Give yourself at least a 25% margin.

3) 800 to 1000kva will work with prop sizes from 10 to 12 inches.

4) I am using this BP Hobbies motor for my heavy lift quadrarotor: http://www.bphobbies.com/view.asp?id=V450327&pid=D1748437 but there are people using 350 watt motors.


Regards,
TCIII

Feliksayk
05-15-2010, 01:29 AM
Hi Nate, I'll try to answer some of your questions.



Here is what I need help with:
1) I see motors listed in 'classes' for helicopters and planes. It seems to go from 100 to 600, and I can infer that this relates to the size of the vehicle. I'm not sure how to translate this into my quadcopter, though. I assume that I should ignore the 'class' and focus on the Amperage and KV ratings?

You should focus on the amperage (or power) and KV rating of the motors. Although it might be helpful if you have had experience with the gas engines to compare. I personally didn't so can't tell you much more on this.



2) For the ESC: should the continuous current output of the ESC be higher than the max amount of current that the motor can draw?

The ESC should always have a higher current rating than the motor you are using. This is to avoid the ESC from burning out if you go full throttle or so. So for a motor that has a max current draw of 20 amps, you should stick with at least a 25 amp ESC.



3) Back to the motors, I have seen a multitude of KV ratings. From what I have read it seems that the 1000Kv range is best for quadcopters. Is this correct?

It has been recommended for a while now to use the motors with around 1000kv rating. I have used anything from 600kv to 1300kv (1300 on a light weight quad). You should generally stick to around 1000kv basically. The science behind it is that the higher kv motors would not be able to produce higher torque required to push a larger propeller, such as a 10 or 12 inch one. They CAN spin smaller props at higher speeds, but if you have larger props, they will quickly heat up and be inefficient.



4) What Amp and KV ratings would be a good motor choice for my 'heavy lifter' quadcopter?

As said before, find a motor with around 1000 kv rating. The amperage you'd want for a heavy lifter is around 15-20 amps per motor so you have overhead power for maneuvers and extra payloads. I love my Hextronik DT750 motors >>> they have a max amperage rating of 18 amps and a 750 kv rating and perform very nicely. There are other motors which are recommended now, such as the Turnigy 2217 16turn 1050kv and the BP A2217-9 950kv motors, though I haven't tried them.



Here is the ESC I am considering. Not sure if it will be overkill or not, but the price is great. If I can find decent motors on this same site that would be great too. Otherwise I'll buy from HobbyKing.
http://www.hobbypartz.com/30a-electronic-brushless-esc-speed-controller--volcano-series-.html

I appreciate any answers you can offer as to be questions, and certainly welcome any suggestions with regard to my motor and ESC choices.

Thanks,
Nate

I can't comment on this ESC. Maybe others here used them, so please give your input. Generally, we recommend the Turnigy Plush series ESCs as they are tested and trusted. They come in many different ratings and if you want an absolute heavy lifter, you should get yourself the Turnigy Plush 30 amps ones, $14 each.

Regards,
Felix

Nate
05-15-2010, 02:44 AM
Thanks for the feedback, everyone! Your input has helped me greatly in my search for components.

Nate

Nate
05-15-2010, 04:37 PM
So I've decided on motors and ESC, but still need some assistance with battery selection.

Motors
http://www.hobbypartz.com/alpha-480--910kv--outrunner-brushless-motor.html

ESC:
http://www.hobbypartz.com/30a-electronic-brushless-esc-speed-controller--volcano-series-.html

Any recommendations for battery size? I am on the fence between 2S and 3S, but I know I need the 20C rated packs. I'll probably be getting a few 1800-2400mAh capacity, and connecting several packs in parallel to maximize flight time. Will 2S be enough for these motors? I tried the calculators posted in another thread, which seem to suggest that 2S will be enough, but I'm not sure I entered all of the parameters correctly. I would much prefer to use the 2S if possible.

The motors draw about 20 continuous max, and I'll be experimenting with both the 10 and 12 props.

Thanks,
Nate

Feliksayk
05-15-2010, 05:08 PM
3S batteries would be better, both for weight savings and lower current draw from the battery. You will also most definitely be better of with a single larger battery than 2 or 3 smaller in parallel. I'd recommend at least the 4000, the 4400mah, or even the 5000 mAh. I am currently looking into using a 5800mAh pack for up to 20 minute flight times, but thats just me.

RoyLB
05-22-2010, 02:26 AM
So I've decided on motors and ESC, but still need some assistance with battery selection.

Motors
http://www.hobbypartz.com/alpha-480--910kv--outrunner-brushless-motor.html

ESC:
http://www.hobbypartz.com/30a-electronic-brushless-esc-speed-controller--volcano-series-.html

Any recommendations for battery size? I am on the fence between 2S and 3S, but I know I need the 20C rated packs. I'll probably be getting a few 1800-2400mAh capacity, and connecting several packs in parallel to maximize flight time. Will 2S be enough for these motors? I tried the calculators posted in another thread, which seem to suggest that 2S will be enough, but I'm not sure I entered all of the parameters correctly. I would much prefer to use the 2S if possible.

The motors draw about 20 continuous max, and I'll be experimenting with both the 10 and 12 props.

Thanks,
Nate

Nate,

Have you had a chance to try out those motors? How was the experience with hobbypartz.com? It certainly looks like a you get a lot of nice accessories with these motors, and the price seems very good. They don't give enough performance data, however.

- Roy

Raihan
06-27-2011, 08:03 AM
CAN I USE THIS BATTERY?

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9932

It's a 3S 1P 30C 5800mAh Battery.......

What charger should I buy for this battery? Which will be perfect?

kha
06-27-2011, 08:15 AM
CAN I USE THIS BATTERY?

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9932

It's a 3S 1P 30C 5800mAh Battery.......

What charger should I buy for this battery? Which will be perfect?

I have this http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=7386

It can charge up to 10A which allows fully charging 5800mAh battery in a little more than half an hour.

It needs an external power but laptop power bricks are good if you're not charging with full 10A