250W geared hub max voltage?
- Thread starter vex_zg
- Start date
dogman dan
1 PW
Depends on the load. Heavy enough bike and rider, you will fry it at 250w.
I would guess that under normal loads, ( rider under 200 pounds) the motor could handle up to 700w fine, 36v with a 20 amps controller. Amp hours of the battery does not matter, that is like size of a gas tank on a car.
I would guess that under normal loads, ( rider under 200 pounds) the motor could handle up to 700w fine, 36v with a 20 amps controller. Amp hours of the battery does not matter, that is like size of a gas tank on a car.
bchaney
100 W
Which motor? I have a Bafang SWXK that I take up to 850w from time to time (not continuous). It's on a 13s battery.
wesnewell
100 GW
Safe, continuously? Well it's rated for 250W, so that's the safe rating. Under normal use, maybe a little higher or continuous operation. Voltage won't matter much as long as you don't exceed the wattage. Of course there or other considerations like the gears/clutch stripping, etc., if you give it too much power/ wattage.
https://endless-sphere.com/forums/viewtopic.php?f=2&t=74403
https://endless-sphere.com/forums/viewtopic.php?f=2&t=74403
wesnewell said:
thanks all for answers, some clarification perhaps:
This is my commuter bike. It's really a really nice package, but...
well currently it tops out at around 25-28km/h. Don't know if it is because kv/rpm has maxed out with this voltage or with amperage of the controller is insufficient. My commute is cca 7km one way.
I'd like to be able to go cca 35km/h and have some 33% more uphill torque. I was thinking to rearrange the battery from 10s3p to 12-13-14-15s 2p, depending on what the controller / motor can take. I really don't need faster than some 35km/h, on this bike at least.
So it's kind of tricky guesstimate question with no guarantees: what amount of overvolting will in your opinion not kill the controller/motor?
Motor speed (kV) is the significant characteristic. It's impossible to make any judgements without knowing what that is. If you have a fast motor and increase the voltage, it will lose efficiency, become sluggish at low speed and overheat. A slow motor can take a lot of voltage increase. It sounds like your motor is restricted. You must derestrict it to find out what its kV is, or you could test it at a lower voltage if you had a suitable controller.
You know whether it's restricted when it runs the same speed with a fully-charged battery as a run-down one. The maximum speed with the wheel off the ground will always be proportional to the battery voltage if the motor is unrestricted.
When you know the motor's maximum speed, come back and tell us how fast it went at what voltage, then we can give sensible advice.
You know whether it's restricted when it runs the same speed with a fully-charged battery as a run-down one. The maximum speed with the wheel off the ground will always be proportional to the battery voltage if the motor is unrestricted.
When you know the motor's maximum speed, come back and tell us how fast it went at what voltage, then we can give sensible advice.
docw009
10 MW
I have a geared Bafang SWXH (250W) running off a 500W S09P controller, usually on 36V. I will run it all up to 52V on occasion when I ride it, but then I only use pedal assist. It will hit 35 kph on 700CC wheels at that voltage, but maybe that's abuse.
We had it up on the bike paths near the Keystone ski area in Colorado earlier this month. These are pretty gentle and the steepest climb is maybe 500 feet in 9 miles. For this trip, I mounted a 48V battery as my wife was the rider and she's not a strong pedaller. She had no problem going 25 km/hour and the motor never got warm. She never got bogged down going uphill, so she wasn't lugging the motor.
I couldn't talk her into taking on the steeper part of the path around Aspen. I would have liked to see how the little motor fared. I would have swapped her into my more powerful BBS02 if we had stalled. As it was, we turned around and it was 10 miles down hill. Fun.
We passed a bunch of other tourist bikers who were gassed out by the 9000 feet altitude. Love these e-bikes.
We had it up on the bike paths near the Keystone ski area in Colorado earlier this month. These are pretty gentle and the steepest climb is maybe 500 feet in 9 miles. For this trip, I mounted a 48V battery as my wife was the rider and she's not a strong pedaller. She had no problem going 25 km/hour and the motor never got warm. She never got bogged down going uphill, so she wasn't lugging the motor.
I couldn't talk her into taking on the steeper part of the path around Aspen. I would have liked to see how the little motor fared. I would have swapped her into my more powerful BBS02 if we had stalled. As it was, we turned around and it was 10 miles down hill. Fun.
We passed a bunch of other tourist bikers who were gassed out by the 9000 feet altitude. Love these e-bikes.
this guy is an inspiration, really pushed the small hub motor far beyond the limits. Filled the hub with ATF fluid. Stripped the gears then replaced them with metal ones.
http://www.bentrideronline.com/messageboard/showthread.php?t=90633
I'll figure out the no loaded/full charged/no speed restricted kv rating ASAP, today hopefully.
http://www.bentrideronline.com/messageboard/showthread.php?t=90633
I'll figure out the no loaded/full charged/no speed restricted kv rating ASAP, today hopefully.
dogman dan
1 PW
Again, depends on the load. If the load is enough, 250w will quickly kill the motor on a hill. Because it will max out at 5mph up that hill, heating up the motor with 200w of waste heat. Ever put your hand on a 100w light bulb? heats up real fast.
But if you pedal hard enough to feel it, and you don't weigh 300 pounds +, go ahead and give that thing 750w. At 14s, that's less than 20 amps.
Obviously, doc's wife is not a heavy girl, so no problem for her on a pretty long hill. The key thing, she does not bog it down. If you are not bogging down now, you won't be on 14s either, so no big problem.
I suspect you will get to 30-35 kph on 14s, 35 kph takes about 400-600 watts for most, so it should handle that continuously fine. Again, if you pedal so you can feel it, you will drop that to 300-500w continuous to go 35 kph. The motor can handle that for sure.
Give it 14s at 25 amps controller, then you are above 1000w peak, and could give the motor too much for it to keep its cool even with a bit less load. But even then, 35 kph cruise on flat ground would still be ok, still be only about 600w max.
You just have to consider the load, because that variable is the one that most affects whether a motor bogs down and smokes itself, or not. 35 kph cruise on flat ground, no wind, rider around 100 kg, should not be that big a load.
But if you pedal hard enough to feel it, and you don't weigh 300 pounds +, go ahead and give that thing 750w. At 14s, that's less than 20 amps.
Obviously, doc's wife is not a heavy girl, so no problem for her on a pretty long hill. The key thing, she does not bog it down. If you are not bogging down now, you won't be on 14s either, so no big problem.
I suspect you will get to 30-35 kph on 14s, 35 kph takes about 400-600 watts for most, so it should handle that continuously fine. Again, if you pedal so you can feel it, you will drop that to 300-500w continuous to go 35 kph. The motor can handle that for sure.
Give it 14s at 25 amps controller, then you are above 1000w peak, and could give the motor too much for it to keep its cool even with a bit less load. But even then, 35 kph cruise on flat ground would still be ok, still be only about 600w max.
You just have to consider the load, because that variable is the one that most affects whether a motor bogs down and smokes itself, or not. 35 kph cruise on flat ground, no wind, rider around 100 kg, should not be that big a load.
so, with a full battery (10s=42V) and no load (wheel spinning freely in the air) the motor tops out at 26km/h, therefore I believe it to be reaching its max speed restricted by voltage, not amperage.
with the wheel being 29" this equals to some 3,12 rotations per second at max speed, or 187 rotations per minute. So increasing the voltage by 50% should give 39km/h unloaded top speed, but I have don't know how many amps/watts does sustaining some 35k-40km/h on flat ground require. I can check this with my other bike running mxus, but don't know if the results are comparable.
After climbing uphill for 500m with minimum pedalling the controller & motor are mildly warm perhaps around 35*C
Ideally, I'd like to use 15s2p (because I only have space for 30 cells in this battery case. If I go for 13s2p then I have 26 cells (so a bit lower capacity).
So 15s or 13s ? I don't care so much if I fry the motor, that I can easily replace, but the controller is neatly integrated in the battery case so wouldn't wanna fry it.
edit: All answers and info was already given to me in previous posts so it is more of a rhetorical question. I'll decide between 13s / 14s /15s considering the controller-frying-risk mostly.
with the wheel being 29" this equals to some 3,12 rotations per second at max speed, or 187 rotations per minute. So increasing the voltage by 50% should give 39km/h unloaded top speed, but I have don't know how many amps/watts does sustaining some 35k-40km/h on flat ground require. I can check this with my other bike running mxus, but don't know if the results are comparable.
After climbing uphill for 500m with minimum pedalling the controller & motor are mildly warm perhaps around 35*C
Ideally, I'd like to use 15s2p (because I only have space for 30 cells in this battery case. If I go for 13s2p then I have 26 cells (so a bit lower capacity).
So 15s or 13s ? I don't care so much if I fry the motor, that I can easily replace, but the controller is neatly integrated in the battery case so wouldn't wanna fry it.
edit: All answers and info was already given to me in previous posts so it is more of a rhetorical question. I'll decide between 13s / 14s /15s considering the controller-frying-risk mostly.
LewTwo
1 MW
Just keep in mind that many controllers are built with components that are rated for a maximum of 60Volts. The popular 14S "52 volt" packs come in at 58.8 volts when fully charged to 4.2 volts. Of course you could try lowering your charge voltage to 3.9 volts.vex_zg said:
How do you come to that conclusion? You need to try again with a run down battery, say 32v, to see if it runs at 20 km/h maximum before you can say that. I'm not aware of a normal 36v hub-motor that runs that slow. That would be a 160 rpm one. The slowest I've seen is 180 rpm. More common is 200 to 230 rpm, but some are as high as 260 rpm.vex_zg said:
dogman dan
1 PW
I would have thought more than 180 rpm no load at 36v. That is one slow wind motor.
But it surely will help to give it as much voltage as your controller can stand. one option for 15s, is just to undercharge slightly, like to 4.1v.
61.5v, not much past the limits, and it certainly will be under 60v in a block.
13s and 14s is easy to find a bulk charger for that voltage. 15s most likely would be harder to find.
But it surely will help to give it as much voltage as your controller can stand. one option for 15s, is just to undercharge slightly, like to 4.1v.
61.5v, not much past the limits, and it certainly will be under 60v in a block.
13s and 14s is easy to find a bulk charger for that voltage. 15s most likely would be harder to find.
well, the funny thing is that the max unloaded motor speed does not seem to depend on voltage. With battery at 60% it is the same as with battery at 100% which probably means that controller is limiting RPM. So by raising only voltage I would not gain more speed.
d8veh said:
this is the manual of the LCD
https://electricbikereview.com/forum/attachments/57689dbfa8e43-pdf.11837/
i can get access to password protected settings. Increasing the actual speed limit works, but the RPMs still are limited to very similar amount.
dogman dan
1 PW
Factory set speed limit is definitely a possibility. That could explain the lower than typical no load rpm.
If it cannot be changed, there is always the option of a cheap 36v 20 amps controller, no display, and a throttle.
If it cannot be changed, there is always the option of a cheap 36v 20 amps controller, no display, and a throttle.
