Motor/controller/battery pairing

[Griswold]

I have an old Kawasaki KD80 I am planning to convert to electric for my son and wanted to get some feedback before I start buying the parts. The bike weighs around 140lbs and the rider is about 90lbs. It will be used like a dirt bike so torque for hills and rough terrain is more important than speed. I am good with it only going 25-35mph. After researching I am planning to go with the combo below

Motor - QS120
Controller - fardriver ND72360
Battery - lifepo4 51.2v 60ah 120amp continuous

Wanting to get some general feedback but mainly wondering if anything is oversized/undersized and is it powerful enough for my plans. Thanks in advance.

 

[harrisonpatm]

I have an old Kawasaki KD80 I am planning to convert to electric for my son and wanted to get some feedback before I start buying the parts. The bike weighs around 140lbs and the rider is about 90lbs. It will be used like a dirt bike so torque for hills and rough terrain is more important than speed. I am good with it only going 25-35mph. After researching I am planning to go with the combo below

Motor - QS120
Controller - fardriver ND72360
Battery - lifepo4 51.2v 60ah 120amp continuous

Wanting to get some general feedback but mainly wondering if anything is oversized/undersized and is it powerful enough for my plans. Thanks in advance.

For a kid, something lightweight like you've described, I'd say you're headed in the right direction. Considering you want to prioritize torque, and you've already picked out a 72v-rated controller, I would at least consider going up to a 72v battery as well. Volt up, gear down, and at 72v, you're gonna get some crazy torque.

But if you stayed at 52v, with the right gearing, it'll probably still be pretty good.

Range? If it's just for local tracks in a circle, you might even be able to get away with less than 60ah, but if you can fit 60ah in your frame, there's no other reason to go with less amperage besides weight and budget.

Looking forward to hearing more!

 

[Griswold]

For a kid, something lightweight like you've described, I'd say you're headed in the right direction. Considering you want to prioritize torque, and you've already picked out a 72v-rated controller, I would at least consider going up to a 72v battery as well. Volt up, gear down, and at 72v, you're gonna get some crazy torque.

But if you stayed at 52v, with the right gearing, it'll probably still be pretty good.

Range? If it's just for local tracks in a circle, you might even be able to get away with less than 60ah, but if you can fit 60ah in your frame, there's no other reason to go with less amperage besides weight and budget.

Looking forward to hearing more!

Thanks. The only reason I was thinking the ND72360 is because the fardriver website listed the watts as 2-3k. The lower option, ND72300 says 1.5-2k watts so I thought it might not be strong enough. But the ND72300 also lists the line amps as 70-110a so even at the lowest 70a I would have thought it could power 3,360 watts at 48v. Not sure how they come up with the motor amps.