Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: Kylepowers on July 31, 2011, 09:57:33 PM

Title: 12V motor 9.6V battery
Post by: Kylepowers on July 31, 2011, 09:57:33 PM

Can i run a 12V motor on 9.6V battery? If so does it cause the motor to draw more amps?

Title: Re: 12V motor 9.6V battery
Post by: Soeren on July 31, 2011, 10:18:09 PM

Hi,

Quote from: Kylepowers on July 31, 2011, 09:57:33 PM

Can i run a 12V motor on 9.6V battery?

Yes, but it will be slower of course.

Quote from: Kylepowers on July 31, 2011, 09:57:33 PM

Can i run a 12V motor on 9.6V battery? If so does it cause the motor to draw more amps?

Just apply a little Ohms Law here...
Assuming the motor takes eg. 2A at 12V. That means that the equivalent DC resistance of the (running) motor is 12/2=6 Ohm
If you apply 9V over 6 Ohm, the current will be just 9/6=1.5A

So, current is reduced, but worse, power is reduced by the square. At 9V it leaves only (9/12)^2=0.56 times the power at 12V.

Title: Re: 12V motor 9.6V battery
Post by: Kylepowers on July 31, 2011, 10:26:18 PM

All right it wont be that much slower in the end the robot wont be fast. The motors only turn at 58 rpms now. so it probably will only spin about 48 Rpms which is not that bad. I can deal with that because for what im working on i don't need something that zips around really fast at this time.

Title: Re: 12V motor 9.6V battery
Post by: Soeren on July 31, 2011, 10:56:59 PM

Hi,

Quote from: Kylepowers on July 31, 2011, 10:26:18 PM

The motors only turn at 58 rpms now. so it probably will only spin about 48 Rpms which is not that bad.

What gives you the impression that reducing power to around 56% will leave you with 83% of the speed?

Title: Re: 12V motor 9.6V battery
Post by: Kylepowers on August 01, 2011, 11:18:10 PM

not very good at math sorry lol.