battery voltage and watts

[Captain]

I have 500 watt Bafang motor with a 48 volt 13 amp hour lithium ion battery from the factory.
Can I use a lower or higher volt battery and diferent amp hour battery without damaging the 500 watt motor or do I need to stay with the 48 volt 13 amp hour battery?
Also, can i use a 1000 watt battery on a 500 watt motor without causing damage?

 

[indianajo]

Different amount of amp hours will not be seen by the motor or controller. Higher amp hour numbers will in general allow you to ride further than lower ones.
Voltage of the battery should be the same as the motor/controller you bought. This is not optional.
Some cells have a limit on the current they will deliver, as the flashlight cells that look just like the 18650 the bikes use are not suitable for bikes. So a "1000 W" rated battery will be fine delivering 500 W you motor demands.

 

[rich c]

Yup, the controller must be figured into the equation. What Bafang motor? Geared or direct? Do you have a display to program the controller? Some folks will hot rod with the numbers, but put a more conservative number in the display. This gives adjustable power and endurance curves for the bike. BUT, if you just lay on a throttle going up steep hills, something will fail by overheating!

 

[harryS]

It's actually the motor controller that determines what voltage is allowable and how much current to deliver. The motor can run at high/low voltages. With a commercial ebike, one should stay with the manufacturer's battery spec for voltage, but you can always go with higher AH, as that just means the battery has more capacity to increase your range.

In the DIY world, hobbyists can select the controller power and not have to match it to the motor, at their own risk of course. SInce I have both 36V and 48V batteries, I like my controllers to be able to run on either. I also lean toward higher current controllers because it's better to have more power and refrain from using it than to not have enough.

Batteries aren't really rated by watts. They're rated by AH. They will tell you the voltage and AH and often leave out the continuous/max current. The AH and continuous current are related, but don't have to be. Some cheaper batteries could have both a highAH rating, but not be capable of supplying high currents. WIth a commercial ebike, you just buy what they recommend as a replacement. WIth a home built bike, you have to make sure the battery can supply the max currents demanded by your controller choice.