# how much voltage can a 48v 13.7 kw motor take?



## Pierre spiteri (Apr 13, 2009)

hi i have a motor is a 13.7kw 48v i still need to measure it regarding inches. How much voltage do you think i can give it?. I would like to give it at least 72v i am still looking for an affordable and efficient controller. I want to power a small car ,which is about 1000kg or less , in Malta we have a lot of hills so i think that the extra torque is needed for stop start hills. I am not thinking for racing yet. can you give me some advice pls?


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## piotrsko (Dec 9, 2007)

you probably can do 72 volts. Count the commutator bars and multiply by {I think} not more than 15 v per segment to get ballpark idea of maximum input voltage.

pictures of the data plate would help, and major should be along to better the cause soon.


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## major (Apr 4, 2008)

piotrsko said:


> you probably can do 72 volts. Count the commutator bars and multiply by {I think} not more than 15 v per segment to get ballpark idea of maximum input voltage.


Hi guys,

I am always reluctant to tell someone how high they can take the motor voltage. There are always many variables. On your volts per bar there, remember to divide by 4. The positive and negative brushes are 90º apart on the comm. But 15V/bar sounds high. Even at 72V I'd use 5º advance. And maybe an extra degree for every 15-20 volts above that.

There is a real nice thing which has happened lately. Controllers can now be programmed to limit motor voltage. It really doesn't require real high motor voltage for the common EV. So you can do a decent battery pack design and figure a way to watch commutation and find an acceptable motor limit. 

Regards,

major


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