I have a somewhat stronger 12V dc motor (stronger meaning it was a part of a door opening system earlier). I'm using it with a PWM motor controller.
After using it i noticed that if i give it a constant PWM signal then the voltage measured at its wire connection drops down like 8-9 %.
for example: i'm using arduino, i give the motor a PWM= 20 signal (at a range PWM 0 - 255 -> 0 - 12 V), the motor spins, i measure the voltage at the motor's connections (it's 1.93 V), i make the motor's shaft unable to rotate (the motor stalls), i measure the voltage again (it's 1.78 V).
I tried it with different input signals (the stalling was performed at a relatively low voltage and for short period of time (so it won't damage the dc motor too much) and i made the measurements with two different DMMs. The 8-9% voltage drops are fairly consistent in the range of used voltages (0.7 - 3.1 V), so i'm assuming it would be the same in the whole range of applied voltage too (0 - 12V).
What could cause this? Isn't just the current that changes at stalling? I measured the current too, and it changes respectively to the motor's datasheet (not higher not lower). I was thinking about stalling causing inner temperature causing voltage drops, but the voltage drops are too similar to me for this case, and also if i stop the stalling (let the motor run again), then the voltage imediately get backs to its original value.
After using it i noticed that if i give it a constant PWM signal then the voltage measured at its wire connection drops down like 8-9 %.
for example: i'm using arduino, i give the motor a PWM= 20 signal (at a range PWM 0 - 255 -> 0 - 12 V), the motor spins, i measure the voltage at the motor's connections (it's 1.93 V), i make the motor's shaft unable to rotate (the motor stalls), i measure the voltage again (it's 1.78 V).
I tried it with different input signals (the stalling was performed at a relatively low voltage and for short period of time (so it won't damage the dc motor too much) and i made the measurements with two different DMMs. The 8-9% voltage drops are fairly consistent in the range of used voltages (0.7 - 3.1 V), so i'm assuming it would be the same in the whole range of applied voltage too (0 - 12V).
What could cause this? Isn't just the current that changes at stalling? I measured the current too, and it changes respectively to the motor's datasheet (not higher not lower). I was thinking about stalling causing inner temperature causing voltage drops, but the voltage drops are too similar to me for this case, and also if i stop the stalling (let the motor run again), then the voltage imediately get backs to its original value.