Compatibility between Battery and Rear Hub electric kit

[Zhelion]

Hello everyone, I would like to know what I should know to buy a battery for a 250W 48V rear hub.
Can I buy any battery? Does the controller have something to do with this? Could I install a 1500w 21Ah battery in my 250W 48V rear hub?

 

[vfr400]

You need to be more specific about which exact motor and controller you have. The controller decides the power, the motor has to be able to deal with it and the battery has to be able to supply it. All three have to to work together.

A battery that can supply 1500w can probably work with any 250w system, but don't think you'll get extra power from your motor without changing the controller.

 

[Zhelion]

You need to be more specific about which exact motor and controller you have. The controller decides the power, the motor has to be able to deal with it and the battery has to be able to supply it. All three have to to work together.

A battery that can supply 1500w can probably work with any 250w system, but don't think you'll get extra power from your motor without changing the controller.

So the controller controls the energy the motor receives from the battery, right? In that case, if the controller is 20A, will it always demand that amount of energy from the battery or does it only indicate the maximum amount of energy it can demand?

Ex: A 48V 17.5Ah battery is approximately 840W if I'm not mistaken. If the controller is 17.5A and the motor is 250W, would everything work correctly? They told me in another post that the battery should be 1.5 higher than the maximum demand of the controller to damage the battery less, but I do not understand everything.

 

[vfr400]

So the controller controls the energy the motor receives from the battery, right? In that case, if the controller is 20A, will it always demand that amount of energy from the battery or does it only indicate the maximum amount of energy it can demand?

Ex: A 48V 17.5Ah battery is approximately 840W if I'm not mistaken. If the controller is 17.5A and the motor is 250W, would everything work correctly? They told me in another post that the battery should be 1.5 higher than the maximum demand of the controller to damage the battery less, but I do not understand everything.

The listing of the battery should show the maximum continuous current that the battery can give. It needs to be at least 20 amps for a 20A controller.

The controller will give 20A at 48v to the motor, which is 960w. The motor will then give out about 620w of output power maximum. You only get the maximum current in the lower half of the motor's RPM range. Once it's up to normal running speed, it generates enough voltage to reduce the current that can come into it. The faster you go, the less current can get into the motor. The 20A is a limit on the controller, not how nuch it gives all the time.

Obviously, if you turn down the power or use low throttle, you'll also get less than 20A.

You're still getting Watts and Watt-hours mixed up. Say in the listing of the battery it says that the maimumum continuous current is 40A. It would then be a 1920w battery (40 x 48).
17.5Ah is its capacity, which is 840Wh (48 x 17.5).

 

[Surf_Wonder]

Hello everyone, I would like to know what I should know to buy a battery for a 250W 48V rear hub.
Can I buy any battery? Does the controller have something to do with this? Could I install a 1500w 21Ah battery in my 250W 48V rear hub?

Your battery need will depend on the average round trip distance and how many times you're expecting to charge. There's many online Battery pack calculators that can help you such as https://ebikeshq.com/electric-bike-battery-pack-calculator/#Calculator but also note ... the higher the Amp Hour and Watt capability of the pack, the more range capability you'll have but note the WEIGHT of the battery pack increases significantly the higher the battery watt rating and amp hour.