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Old 06-13-17, 10:02 AM   #1
Slipinn
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350 or 500 watt controller on a 250 rear geared hub motor?

I Have a 250 watt 36v rear brushless geared hub motor on a 8.8ah battery and would like to know if I can install a 36v 350 watt controller or a 36v 500 watt controller and 15ah battery and realize anymore torque or speed without harming the motor. the ebike is a ancheer folding mtb with mag wheels. I read a 250 watt motor could handle up to 500 watts safely on a few sites. I live in Florida and the land here is pool table flat.
Thanks for your help and sharing some knowledge with me

Chuck
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Old 06-13-17, 08:35 PM   #2
Doc_Wui
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The speed will not change, as the motor speed depends on voltage. You might feel more of a kick with a larger controller if you have a throttle.

I have a little folding bike with a 250W motor too, and its acceleration was nil with a 10A 36V controller, and a little stronger with a 17A 36V controller, but top speed is still 16 mph.

If you're changing controllers and batteries, although the latter sounds tough if the Ancheer has the integrated battery, why not upgrade to 48 volts? I put in a 36V/48V controller on my folder. Top speed, if I choose to run a 52V battery is around 22 mph, and short term power input is 900 watts. Probably not good, but I think 48V is safe.

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Old 06-18-17, 02:22 PM   #3
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You are either reading the wrong sites or did not read completely.

Can most 250-watt motors handle more wattage? The answer is almost always yes, FOR A LIMITED AMOUNT OF TIME. How long? Well, use a stopwatch, and when you see the smoke come out, that was just a little bit too long. After you purchase the replacement motor, don't do it for that long again.

There are various motor simulators which can give you a decent estimate of overheat times, if you know the brand name of the motor.
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Old 06-19-17, 07:47 AM   #4
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I had the 48V battery mounted on my wife's folding bike with its 250W motor yesterday and she never went much over 12 mph except for a hill. I rode my regular bike, knowing she is slow.

In the evening, I took her bike out to see what kind of power was being used. It has an LCD meter with power use. About 120W in first level PAS. Up to 200W in 2nd level, which was 14 mph and then I blew a tire. Had to walk home 1/2 mile. See. That's what big power does to us.

Seriously, I have three motors that are small diameter, less than 110mm hub diameter, and had no qualms installing 500W 48V controllers on them. Just common sense on use. I've never run a motor to the point where it gets uncomfortable to touch, like 120F or more. If it feels that hot, and you run it hotter, the plastic/nylon gears are sure to melt.
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Old 06-22-17, 11:04 AM   #5
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250 watt geared hub motor

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Originally Posted by Doc_Wui View Post
I had the 48V battery mounted on my wife's folding bike with its 250W motor yesterday and she never went much over 12 mph except for a hill. I rode my regular bike, knowing she is slow.

In the evening, I took her bike out to see what kind of power was being used. It has an LCD meter with power use. About 120W in first level PAS. Up to 200W in 2nd level, which was 14 mph and then I blew a tire. Had to walk home 1/2 mile. See. That's what big power does to us.

Seriously, I have three motors that are small diameter, less than 110mm hub diameter, and had no qualms installing 500W 48V controllers on them. Just common sense on use. I've never run a motor to the point where it gets uncomfortable to touch, like 120F or more. If it feels that hot, and you run it hotter, the plastic/nylon gears are sure to melt.
Thanks for the replies. I'm 70 yrs old so no longer hot dog my bikes or motorcycles. I use the bike for local commuting but would like a little more torque. I was reluctant to go 48v on it due to heat so thought maybe the best thing would be to stay at 36v and just push more watts to it. I did see a chart that showed that a bigger ah battery would feed more watts to the motor if the controller amp rating was sized to accept more amps. So was thinking to go from the 8.8ah battery which is a bag mounted battery to a 15ah and then going to 350 or 500 watts on the controller. Thought that might be the lesser of the two options to help ensure durability and less chance of motor damage.
What I find with this mtb is that in 21st gear and throttle wide open the motor is running faster than any pedal input so the pedals simply spin and give the motor no added help. I think is I change the crankset from its 42/32/22 to a 48 tooth final drive that it will allow me to help the motor at top end to reach its max rpm and result in a little more top end in full throttle and PAS. My former bikes were all bigger. The last I built was a 1200 watt 20ah bldc front drive trike which went 36mph but sold that to an neighbor who injured his ankle and could no longer use his road bike. Just wondered if anyone had upped the power to a 250 geared hub motor to higher watts or volts and find its been dependable.
I thought about changing the motor but the bike has mag wheels and the hub motor fits into the rear mag. Not sure if motors this size that are more wattage are the same diameter. All I find on the actual motor is an id number of 36v J16110330 . Would be nice to be able to buy a higher wattage motor and just remove the motor from its hub and drop it into my mag wheel hub. I imagine many of these small motors are basically the same size and the mfgr just made mag wheels to fit the 250 watt geared hub motor that was already available. Just not sure how to ID them so as to get a replacement in higher wattage bu the same demenitions .
Thanks to all who responded thus far and looking forward to hearing more on this.
Chuck

Last edited by Slipinn; 06-22-17 at 11:22 AM.
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Old 06-22-17, 01:41 PM   #6
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Hey Slipinn,

Generally, it is safer (less heat) to get more power by increasing the voltage than the current. But more voltage will give you more speed, if you just want more torque, you need more current.
In general, yeah, you can put 48v volts or maybe 20% more current through a motor if you are not climbing hills, or doing anything where you would be using full throttle at less than have the maximum cruising speed for less than a couple of minutes. Any of these changes would need to be done with the controller.

Bigger batteries do not feed more power to the motor, only a bigger controller will give you more current. An 8.8ah battery is the same as a 15ah battery in this case. (to get detailed, the 8.8ah battery probably won’t be able to give you much more current than what you have, so to get more current you would need to modify the controller, and then get a battery that can handle the additional load).

For small motors and controllers:
250 watt controllers are generally 24 volts
350 watt controllers are generally 36 volts
500 watt controllers are generally 48volts

The above could all be the same motor. The above also assumes you are using a very small controller with a 15 amp peak and 10amp average draw. Obviously if you increase the current to something above the minimum current, you can get any power level you want (theoretically).


I don’t know the specifics of your motor, so I’m just generalizing. It all could be wrong. But yes, most of the small 250 watt Chinese motors are of a similar design.

Yes, a 48 tooth crank is a great idea.
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