veloman said:
I have an old EvT 168 electric scooter with a 1500w brushed hub motor. I know its old tech, but it still works and the scooter was very cheap. I noticed the motor slows down quickly and I don't coast very far when riding. So my thought is - this could be regen if I had a controller with that function. But I am not getting regen, so this must be 100% heat loss - very bad for keeping the motor from getting hot. Maybe its only 50w drag. But my ebike with a clyte ht hub coasts way better than this scooter.
I assume you've already checked mechanical sources of loss like brakes or bearings?
If you're geting zero current back to the battery then that means all the power is being wasted inside the hub *or* the contorller.
If you have an external shunt on your CA or watt meter, you could put it in series with the motor/controller wires, instead of the battery/controller. Then you can see if there's any power going back to the controller, the FETs may be turning on partially and shorting out the motor coils a little, draining momentum from the motor/wheel.
If no power is going back to the controller, then it's possible there is simply a lot of frction on the burshes/commutator, either from springs that are too strong or something else isnide the hub. I guess it's possible alos that magnetic eddy currents from the magnets into the coils or laminations could also heat things up and slow it down, but I don't know enough about that part--brush friction is a common issue with brushed motors, though.
is there any way to easily mod to get some regen power on this scooter?
If the controller is designed for regen, you could probably do it easily enough--but it is possible to design a brushed contorller so that it can't do regen, AFAIK, and if they did it that way tosave money, you'd have to change the controller. I don't remmber the physical differences off the top of my head, but if you go ot the 4QD website there is a tech section that discusses the beginnings of brushed motor control and I think talks about that specific thing.
I am pushing the hub pretty hard with 67v and 100amps peak, so it gets warm after even 3 miles. I'm not sure it will handle the summer heat here.
What's the continuos current? and how often do you acclerate hard enough to see that high peak A, and how long do you see anythign that high on it?
Remeber also that hte higher voltage you use on a brushed motor, the more wear and heat you get on the brushes and comm, plus you get more RFI spikes back into the FETs on the controller from brush arcing, and that can damage the controller. (sometimes the spikes get thru the FETs and damage the gate transistors without damaging the FETs noticeably, according to a couple of guys I talked to about that years back when I was first learning about motors).
My big issue with this scooter is that the kds i hooked up is making it really slow off the line. I have it on max power settings. It pulls great once above 20mph. Any ideas?
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KDS? Is taht the controler?
Do you get a lot of voltage sag on the battery? If so, that'll cause your slow off the line issue just cuz there's less total power being delivered, at the higher current of startup.
It could just be that the motor is wound so that it is ssetup for higher speeds and not for high torque? At least, in the size wheel it's in? I think that is the big issue I have with both the HSR3548 in 20" wheel, and 9C 2806 in 26" wheel, that i've used most recently on CrazyBike2. If I use both motors together at startup it's quicker off the line than either alone, with several seconds difference between 0-20MPH on one motor vs two. Once I get close to 20MPH either one gets up there quick, but not off the line. Part of it is the controller; only 40A max on one and 20A on the ohter (tested both combinations of motro/controler with same results).
