Selecting a Motor

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Re: Selecting a Motor

Postby Bazinga+ » January 16th, 2016, 3:20 am

Well said.
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Re: Selecting a Motor

Postby iwonder » January 21st, 2016, 7:15 pm

windu34 wrote:Brushless A/C motors will not be able to maintain a steady position without some serious algorithms


I'm a bit late I know, but most all brushless ESC's I've seen have a brake feature that stops the motor. One of the best features of BLDC motors (imho) is that they have a holding torque, and it's pretty straightforward to implement.
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Re: Selecting a Motor

Postby rk9109 » January 30th, 2016, 8:43 pm

Here's one thing I don't get. All of the brushless motors I've found tend to run at rather high voltages - how do you manage to run them with only a 9V power supply available?

We are currently using basic DC motors for 2 of the wheels running at 4.5 V each - I can't find any brushless motors that would take such a small voltage.

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Re: Selecting a Motor

Postby InfiniCuber » January 30th, 2016, 8:47 pm

rk9109 wrote:Here's one thing I don't get. All of the brushless motors I've found tend to run at rather high voltages - how do you manage to run them with only a 9V power supply available?

We are currently using basic DC motors for 2 of the wheels running at 4.5 V each - I can't find any brushless motors that would take such a small voltage.

Use a voltage step-up converter:)
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Re: Selecting a Motor

Postby Bazinga+ » January 31st, 2016, 5:40 am

InfiniCuber wrote:
rk9109 wrote:Here's one thing I don't get. All of the brushless motors I've found tend to run at rather high voltages - how do you manage to run them with only a 9V power supply available?

We are currently using basic DC motors for 2 of the wheels running at 4.5 V each - I can't find any brushless motors that would take such a small voltage.

Use a voltage step-up converter:)

I wouldn't. Which brushless motors are you talking about? All the ones I've seen are run by 2-3 cell lithium ion batteries or 5-8 Nickel cadmium batteries. A 6 cell buckle battery is 7.2 volts, so definitely in specs. I recommend a nice castle or turnigy brushless motor/esc combo.
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Re: Selecting a Motor

Postby InfiniCuber » January 31st, 2016, 11:38 am

Bazinga+ wrote:
InfiniCuber wrote:
rk9109 wrote:Here's one thing I don't get. All of the brushless motors I've found tend to run at rather high voltages - how do you manage to run them with only a 9V power supply available?

We are currently using basic DC motors for 2 of the wheels running at 4.5 V each - I can't find any brushless motors that would take such a small voltage.

Use a voltage step-up converter:)

I wouldn't. Which brushless motors are you talking about? All the ones I've seen are run by 2-3 cell lithium ion batteries or 5-8 Nickel cadmium batteries. A 6 cell buckle battery is 7.2 volts, so definitely in specs. I recommend a nice castle or turnigy brushless motor/esc combo.

Um..why not? If you honestly need the voltage (and I know I did) it works like a charm. There's no harm in trying one. Although if you do find one that only requires the small 7.2 volts, go for it!
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Re: Selecting a Motor

Postby Bazinga+ » January 31st, 2016, 6:29 pm

InfiniCuber wrote:
Bazinga+ wrote:
InfiniCuber wrote:Use a voltage step-up converter:)

I wouldn't. Which brushless motors are you talking about? All the ones I've seen are run by 2-3 cell lithium ion batteries or 5-8 Nickel cadmium batteries. A 6 cell buckle battery is 7.2 volts, so definitely in specs. I recommend a nice castle or turnigy brushless motor/esc combo.

Um..why not? If you honestly need the voltage (and I know I did) it works like a charm. There's no harm in trying one. Although if you do find one that only requires the small 7.2 volts, go for it!

Voltage converters are better avoided if possible. In case you don't know, voltage converters have resistors in them, meaning that some of your energy will be lost to heat, not to mention the risk of something heating up and burning up is much more present. Also, when you use a voltage converter the voltage you receive fluctuates a bit more than when its coming directly from a battery, and not to mention most microcontrollers don't work as well at voltages higher than 9.
Innovation =/= success

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Re: Selecting a Motor

Postby InfiniCuber » January 31st, 2016, 7:19 pm

Bazinga+ wrote:
InfiniCuber wrote:
Bazinga+ wrote:I wouldn't. Which brushless motors are you talking about? All the ones I've seen are run by 2-3 cell lithium ion batteries or 5-8 Nickel cadmium batteries. A 6 cell buckle battery is 7.2 volts, so definitely in specs. I recommend a nice castle or turnigy brushless motor/esc combo.

Um..why not? If you honestly need the voltage (and I know I did) it works like a charm. There's no harm in trying one. Although if you do find one that only requires the small 7.2 volts, go for it!

Voltage converters are better avoided if possible. In case you don't know, voltage converters have resistors in them, meaning that some of your energy will be lost to heat, not to mention the risk of something heating up and burning up is much more present. Also, when you use a voltage converter the voltage you receive fluctuates a bit more than when its coming directly from a battery, and not to mention most microcontrollers don't work as well at voltages higher than 9.

I've used many many voltage converters, and it really depends on which you get. The one I have gives a continuous voltage output even with a load, and barely heats up. The single problem I have had is that my battery dies faster because I have my battery going to the voltage converter and then driver and then in parallel I have another lead going to my microcontroller, (arduino) so the voltage isn't an issue. Plus, the battery charges up quickly. Sure, the risk is there but if you buy a good one it isn't much of a problem. I have a larger problem with my driver heating up than my voltage converter, and even then, yes energy is lost but I get sufficient power to run my vehicle how I want it. Again, it really is only an issue of keeping your battery charged. I recommend using them if you need to, but I understand why you avoid them. Just nothing to be scared of though!
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Re: Selecting a Motor

Postby Bob_117 » February 9th, 2016, 12:27 pm

I was going to use a brushless motor but I smoked while trying to figure out the coding :? . So I went with a relatively cheap 55 turn crawler motor and have been getting times under 2.5 seconds for a 9m run. I could go faster but I have brake before 8.5m.
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Re: Selecting a Motor

Postby InfiniCuber » February 9th, 2016, 4:49 pm

Bob_117 wrote:I was going to use a brushless motor but I smoked while trying to figure out the coding :? . So I went with a relatively cheap 55 turn crawler motor and have been getting times under 2.5 seconds for a 9m run. I could go faster but I have brake before 8.5m.

If you can find i way to go backwards, you don't have to brake before 8.5m.
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Re: Selecting a Motor

Postby Bob_117 » February 10th, 2016, 1:18 pm

InfiniCuber wrote:
Bob_117 wrote:I was going to use a brushless motor but I smoked while trying to figure out the coding :? . So I went with a relatively cheap 55 turn crawler motor and have been getting times under 2.5 seconds for a 9m run. I could go faster but I have brake before 8.5m.

If you can find i way to go backwards, you don't have to brake before 8.5m.

Thats what I was going to do but it takes about 4m for my car to come to a stop and at previous competitions there hasn't always been that much room for stopping. So I'm braking about 3m before target distance and then backing up to the line.
There is nothing like the last minute rush to get your cheatsheets organized the night before the big day :D

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