16 volt motor and resistor

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Printed Date: May 01, 2025 at 12:31 PM

Topic: 16 volt motor and resistor

Posted By: troy8143
Subject: 16 volt motor and resistor
Date Posted: May 18, 2011 at 10:54 PM

I race drag slot cars and I am trying to reduce the voltage of my motor from 16v to 1v.

To be safe im going to assume it pulls about 4 amps at 16 volts. (64 watts) At 1 volt I am assuming it will pull about .85 amps

Basically i need to pick out a resistor (or multiple resistors) that will not burn up, I dont know much about different resistors in anything more powerful than a small pocket amplifier.

What ohm rating and wattage would i need? where do i buy resistors?

Replies:

Posted By: oldspark
Date Posted: May 19, 2011 at 2:52 AM

V=IR => R=V/I

R = (16-1)/.85 = 15/.85 = 17.6

Hence 18 Ohms (a preferred value).

P=VI = (16-1)*0.85 = 15*0.85 = 12.75W.

Hence 20 Watts (preferred size).

Hence an 18 Ohm 20W resistor based on your info.
(Likewise, the motor will have ~1.3% of the original ie, 1/75th the power from 1*0.85/16*4 = 0.85W/64W = 1/75)

Posted By: troy8143
Date Posted: May 19, 2011 at 8:32 AM

Thank you very much. I appretiate you showing the math with it. Now if i can just find one locally for less than 5$ ;)

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