Volts, Amps and Power

[DJH]

Continuing in my search for knowledge after my previous post 'Talk Torque', I would now like to explore the relationship between volts, amps and power. I have a 24v 10ah battery with a 250w hub motor. If I had, say, a 36v 14ah battery with a 250w motor would that effect the amount of energy I had to put in to climb a hill. I realise with the more powerful battery the range is increased but I just wondered what effect it had on the power as the motor is still 250w?
Many of these issued could be sorted out practically if there were dealers close by, but as they are few and far between in this part of the world they can only be answered with facts and figures through the ether.

 

[NRG]

You would require the same amount of energy to climb the hill, the controller limits what the motor draws from the battery. Infact if the new battery was larger and heavier you would require more energy to get up the hill!

The larger battery will give you more range given the same motor and controller combination. A good way to think about this is in Watt Hours (Wh) 36vx14Ah is 504Wh, given, say an average consumption of 12Wh/Mile you can work out your range, approx 42Miles.

Of course this depends on your fitness and the terrain you cover.....

I should add the larger battery will also hold up better under load, due to the higher capacity the voltage will sag less under load than the 10Ah giving the feeling of power for longer...

 

[Scottyf]

In simple terms.

The larger battery the more watts you have to play with (watts = volts x amps)

Using hub motors - More volts = faster rpm. More amps = more torque

The controller is the restriction box. This basically stops the motor drawing as much current from the batteries as physically possible. Else your battery would just try to dump all its power ASAP.

Electric motors will take any combination of volts or amps. They will draw power untill they fail on heat.
This is why a controller is used.



If in the above example. you went from a 24v 10ah battery and changed it for a 36v 14ah battery you would increase speed and total watts