Scooter battery for ebike

OliUK

New Member
Hi all.
I am.at the planning stage of building my own ebike.
As we all know one of the most expensive parts will be the battery.
I already own a xiaomi M365 scooter with a 36v 7800 mHa battery in it.
Do you think I could use the battery for both vehicles if I create a suitable carry case for the battery when it's on the bike?
I'm thinking of using a 500W front wheel e-bike conversion kit.
Any thoughts would be greatly appreciated.
 

indianajo

Well-Known Member
Volts are volts and watthours are watt hours. If you have a scooter battery that actually works, a vise hacksaw & a drill motor, more power to you.
I built a mount for a 17.5 ah LiFePo4 scooter battery I bought for $300. It would work for 7 miles before voltage dropped to 7. I got my money back from Amazon, bought one from E-bay. It would work for 11 miles before failing, voltage bounced back to 50+ as soon as I turned the motor off. I had to pedal that one 26 miles to town and load it with a 10 ohm resistor to prove it was going to 11 volts under load from full charge. Didn't get my money back on that one, took too long devising a test to prove it was garbage. Both batteries used insulated .250" flag terminals on the wires. If your controller can draw 25 amps or more buy the taiwanese or US made crimp terminals. The ****ese ones melt out at that current. Pull test your crimp for quality after making it.
I use a front wheel hub motor kit. I have the battery mounted over the front wheel for weight. Works fine, but not on ice, mud, wet steel or rock or wood bridge decks. There I pedal myself or walk.
 
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OliUK

New Member
Thanks for that indianajo 👍. One of my concerns was the BMS, do you know if this would this cause problems of incompatibility?
 

indianajo

Well-Known Member
As far as I know, BMS is only active during charging. Use your existing charger. While discharging BMS has no function.
 

harryS

Well-Known Member
A battery will run an ebike, if it has enough power. The AH rating will tell its capacity, but you need to know the maximum current the pack will sustain. You need around 20A to run a 500W controller. You might get by with 10-15A if you never crack the throttle and ride slow in lower assist, but you will want that current. It's not often listed for scooter packs.

I've run my 500W controllers on scooter and hoverboard packs. Some have the capacity. Some don't. Actually, most won't. These packs are only 4AH-6AH, and I use two in parallel.

So build your ebilke, and if your xiaomi happens to be strong enough to be re-used, well that's great. If you are going to run your bike on 36V though, another consideration is to wire it in parallel as a helper battery. The main caution for safety is you can only hook them together when both are at the same voltage, usually freshly charged. You have to take them apart to charge too,

I have several small ebike batteries, only 7AH to 8AH. For a longer ride, adding 5AH-10AH in parallel works for me.
 
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OliUK

New Member
A battery will run an ebike, if it has enough power. The AH rating will tell its capacity, but you need to know the maximum current the pack will sustain. You need around 20A to run a 500W controller. You might get by with 10-15A if you never crack the throttle and ride slow in lower assist, but you will want that current. It's not often listed for scooter packs.

I've run my 500W controllers on scooter and hoverboard packs. Some have the capacity. Some don't. Actually, most won't. These packs are only 4AH-6AH, and I use two in parallel.

So build your ebilke, and if your xiaomi happens to be strong enough to be re-used, well that's great. If you are going to run your bike on 36V though, another consideration is to wire it in parallel as a helper battery. The main caution for safety is you can only hook them together when both are at the same voltage, usually freshly charged. You have to take them apart to charge too,

I have several small ebike batteries, only 7AH to 8AH. For a longer ride, adding 5AH-10AH in parallel works for me.
Thanks very much @harryS , I have just looked up the full spec of the battery and it reads as follows. So I am confident that I will be able to use it. Thank you for your detailed reply

Nominal voltage: 36 V
Core Brand: Imported LG
Capacity: 7.8ah
Nature: 30 knots 10s3P
Output Current (A): 15-20
Power: 280WH
Driving mileage: 30 km
Charger rated input voltage: 100-240V~, 50/60Hz
Battery charging limit voltage: 42V
 

indianajo

Well-Known Member
I already own a xiaomi M365 scooter with a 36v 7800 mHa battery in it.
I'd much rather have 7.8 AH instead of 7800 milliHas. 7 Has must punctuate a pretty good joke.
15 A limit would get you 540 voltamps. Pretty good.