Originally Posted by
Doc_Wui
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