# Overvolting a BLDC motor



## jumpjack (Sep 9, 2012)

How much voltage can I provide to a BLDC motor without burning it up? Which data should I read on the datasheet?
For example, how can I know how high can I bring the voltage of my 48V scooter to get higher speed? (But I have no datasheets for it...)


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## Salty9 (Jul 13, 2009)

Check http://endless-sphere.com/forums/viewforum.php?f=30


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## jumpjack (Sep 9, 2012)

Other tips?


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## gunnarhs (Apr 24, 2012)

jumpjack said:


> Other tips?


If you want to do that without data sheet, just by experiementing, you should measure current and temperature of the windings and calculate the change in resistance / heat due to higher voltage.
For this example of a 48V motor, I would start measuring this values at about 30V and then slowly increase the voltage an 5V steps.
Let the motor run at the specific voltage (and same load!) at least for five minutes before noting down the final current/heat values (but watch it every second when getting over 48V !)
For a BLDC (or PMSM) with stator coils and magnetic field in rotor (most types I know) you will notice a point where

1) The motor does not increase the speed as much as in prevous step
First indication of limit

2) The current drops, resistance goes up, rotor oscillates under load
Here the wonders of PMSM become a problem for Motor control Unit

3) The coils and motor start heating considerably (more difficult to measure when coils in rotor)
Danger of destruction.


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