Is motor too weak?

Lightweight / Folding / Portable EVs - seats optional
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gmacd1177   10 µW

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Is motor too weak?

Post by gmacd1177 » Apr 27 2016 11:41pm

Trying to make an electric long board for a class project and when the trigger is pulled to speed up, it 'clicks' as if it does not have enough torque to actually add power to the wheels. The motor is brushless so the clicking sound I imagine is from the magnets going back and forth rapidly (rather than actually turning over).

The motor that I bought is:

http://www.hobbyking.com/hobbyking/stor ... Glow_.html

This seems very similar to motors used in other builds so I'm not sure why it isn't working. I mean it works fine when nobody is on the board and will accelerate just fine, but when someone stands on it it lugs the motor too much.

If it matters we are using two 12 volt batters in series to power it. Any ideas?

Thanks!

stealth71   10 W

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Re: Is motor too weak?

Post by stealth71 » Apr 28 2016 12:59am

What kind of ESC, wheel size, and drive ratio?

gmacd1177   10 µW

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Re: Is motor too weak?

Post by gmacd1177 » Apr 28 2016 2:28am

This is the ESC:

http://www.hobbyking.com/hobbyking/stor ... _SBEC.html

Does the type of ESC make a difference?

The wheel size is ~4" diameter and drive ratio that we are going for is 3:1 (3 motor turns per wheel turn).

gmacd1177   10 µW

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Re: Is motor too weak?

Post by gmacd1177 » Apr 28 2016 2:41am

Also I should mention that the motor seemed very weak even by itself. I could hold it with two fingers and full throttle would not spin it. It just 'clicked' like I mentioned before. I feel like there is something wrong here because even cordless drill motors have enough torque that I cannot hold with my hand. Is there some time of setting or configuration that allows for more torque rather than high rpm?

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LEVer   10 kW

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Re: Is motor too weak?

Post by LEVer » Apr 28 2016 2:42am

its called cogging torque. try to kick first before using the throttle. once it gets going a bit, it'll be fine.

WeeChumlee   1 kW

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Re: Is motor too weak?

Post by WeeChumlee » Apr 28 2016 9:20am

Pretty important - What 12V batteries? Can they deliver the power needed?

gmacd1177   10 µW

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Re: Is motor too weak?

Post by gmacd1177 » Apr 28 2016 12:25pm

I think 3 cell batteries. I think they actually provide 11.1V each, but 12.2V in series.

WeeChumlee   1 kW

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Re: Is motor too weak?

Post by WeeChumlee » Apr 28 2016 5:47pm

Lipo batteries or what. What is their caspacity , as in amps per hour? If you don't know post a picture.
Best if you post a picture of everything.

gmacd1177   10 µW

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Re: Is motor too weak?

Post by gmacd1177 » Apr 29 2016 1:54am

It is a group project so I do not have the batteries in my possession at the moment but I believe 3500mA Lipo.

WeeChumlee   1 kW

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Re: Is motor too weak?

Post by WeeChumlee » Apr 29 2016 3:03am

You are using a pretty small motor with a pretty high KV rating - not a good combination.
Without load it probably flies but as soon as the board is loaded with the weight of a human then it will definitely need a good hefty kick start.
Once rolling along a smooth flat it should be OK with someone on it that is on the lighter side.
Don't try hills or lots of start/stops you will probably fry the motor very quickly.
What you really need to do is shell out just a little bit more and get a 63mm motor - KV range from 150 -> 250.

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