Controller rated watts

[Welly_59]

If I had a controller marketed as 36v250w and another at 36v350w, is there actually any difference if the ampage is the same ie 12amp output?

As I understand it the wattage is a product of volts X amps, so in both instance 36x12 is actually 432w

Or is there some other ingredient I am missing?

 

[Nealh]

They would both be the same, usually watt marked controllers have differing current values.

 

[Welly_59]

Thanks, thought so!

 

[vfr400]

The rating of 250w or 350w is not how much power it gives, but how much it can run at continuously. 250w is roughly 7A, so if you ran at maximum power for more than a short time, it would overheat. 350w gives you 9 A continuous.

Note that 7A from a 14AH battery would last 2 hours. At 14 mph average, that would give you a range of 28 miles, which is probably a bit less than what an average ebiker gets, An average ebiker probably averages something like 4 or 5 amps on an average hilliness ride.

Note also, that setting maximum power for your ride only gives maximum power when you're riding slowly. The current goes down as your speed goes up until you get zero current at the motor's maxi um speed.