Batteries to correspond to Motor

[amaroq]

On Cyclotricity I see that they offer 48v batteries for 1000W motors and 36v batteries for 500W motors. Does it follow that 24v batteries are only suitable for 250W motors?
Is there a rule of correct and appropriate correspondence between Motor W and Battery V ?

I was looking to self-build with a kit and looking to purchase a bike someone else has already built and looking for some knowledge and confirmation. This e-bike conversion has a front wheel 1000W motor but the battery is only 24V, which he acknowledges is inadequate but will it do for now until there's money for an upgrade?
I don't know how, but he says that the battery recharges while cycling when the motor is off or something... So, unsure what the setup is. Going to look at it...

 

[trex]

it's more a case of matching battery to the controller.
The battery has to be able to supply enough current to support the controller without too much sagging. For example you have a 20A controller and a 10AH battery. When the controller pulls 20A from of your 10AH battery, you may see a 3V drop in the voltage. If you use a 15AH battery with the same controller, you would see 2V drop. You may think 1V difference is not important but that extra drop is inside the battery where it causes prematured failure.

 

[Alan Quay]

On Cyclotricity I see that they offer 48v batteries for 1000W motors and 36v batteries for 500W motors. Does it follow that 24v batteries are only suitable for 250W motors?
Is there a rule of correct and appropriate correspondence between Motor W and Battery V ?

I was looking to self-build with a kit and looking to purchase a bike someone else has already built and looking for some knowledge and confirmation. This e-bike conversion has a front wheel 1000W motor but the battery is only 24V, which he acknowledges is inadequate but will it do for now until there's money for an upgrade?
I don't know how, but he says that the battery recharges while cycling when the motor is off or something... So, unsure what the setup is. Going to look at it...

There's no theoretical correspondence between volts and power, since
power = Volts x Amps

This means that with enough current, you can get just as much power with a lower voltage, however......

Batteries have a finite amount of current that they can deliver at any one time, so in practice, more V allows for more P.

To get 1000w at 24v you are looking at 40+ Amps. This will require thick cables, beefed up connectors and a very high capacity battery.

1000w at 36v is around 30A, and 20A at 48v.

As for batteries recharge in while you pedal, even if it does work, it won't be worth having.

I would also be weary of '1000w' motors. Most are direct drive (no internal gearbox) which makes them poor climbers, although fast on the flat.

I'd also be careful of that much power in the front.

All in all, I'd avoid it unless you have some very specific requirements.



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