Why? Did you figure out what the ratio would be?Hi,
Would it be ok to use a motor running nearly at half its rated speed because of the load? It like to use a 895 DC 3000-6000rpm motor with a 80T sprocket connected to a 12T sprocket to reduce the stall effect
So you see this is for an diy electric bike. I want to use a 895 dc motor that runs at 12v 3000rpm 5kg/cm torque and at 24 6000rpm 10kg/cm torque . I can gear it down with a ratio of 8 to 1, so the rpm would become 375 at 12v and 750rpm at 24v. The bike will go at to maximum of 25km/h, after that the motors will stop working (because of the law). but even just 12v 375rpm is about twice as much as the rpm that the wheels will have at 25km/h. So i'm worried this will not be efficient/ effective at all? I mean will it even be able to exert some torque in this scenario?A typical DC motor can be ran at any rpm usually, you just need to observe the wattage rating.
Gearing is the more efficient/preferred way.
When ran a really low RPM, cooling may be needed also.
Max.
Gear it down more (16:1 ?), then run the motor at full power - far more efficient, and you'll get much better performance as well.So you see this is for an diy electric bike. I want to use a 895 dc motor that runs at 12v 3000rpm 5kg/cm torque and at 24 6000rpm 10kg/cm torque . I can gear it down with a ratio of 8 to 1, so the rpm would become 375 at 12v and 750rpm at 24v. The bike will go at to maximum of 25km/h, after that the motors will stop working (because of the law). but even just 12v 375rpm is about twice as much as the rpm that the wheels will have at 25km/h. So i'm worried this will not be efficient/ effective at all? I mean will it even be able to exert some torque in this scenario?
Doesn't look like he has the room, it is a small dia roller driving the bicycle tire directly.Gear it down more (16:1 ?), then run the motor at full power - far more efficient, and you'll get much better performance as well.
Yes i'll make it with a chain and a freewheel. the motor i'll use is this: https://www.ebay.com/itm/254457889235?ul_noapp=true , which with the wheel size being 27 inches should give me 25km/h at 250w 2000rpm , which is the legal limit.In one of these many forums, he said he will use a sprocket and chain system instead of the silly wooden roller wearing out the wobbling tire.
I do not know any product that uses a cheap brushed DC motor running for an hour or more when heavily loaded. Won't the brushes quickly wear out or burn out soon in this bike application? Don't real electric bikes use brushless motors that last forever?
That depends on how the controller has been designed.I was thinking, would it work if i replace the potentiometer input with a 5v DAC input from the Arduino?
it would be easy to make a spoke counter and measure the time between spokes interrupting an optical beam, or, better option would be spokes reflecting an optical beam. you'll have to cut out the motor if spokes are passing the semsor faster than once per (about) 18.5mSec with a typical 27" tire.It has to shutdown the motor after 25 km/h,
Real similar to what I suggested in one of his other threads.Here you go Max.
Is 27 inches the actual tire diameter, or is it the rim size? either way you need to do some more math. You need to figure out the tire circumference to find out the RPM to make your 25km/h and then find what gear ratio is needed to get that speed.which with the wheel size being 27 inches should give me 25km/h at 250w 2000rpm