Here is my little problem. I installed a 48 volt controller (YK42-4) on my MX500 with the stock 500 watt motor. The bike has the stock throttle and one brake cut off going to the new controller. It has 4, 12 volt batteries and runs great at half and three quarter throttle but when I open it up it has this stutter/hesitation for just a mili second at a time that comes and goes. Any ideas?
What is happening is that your controller is pulling more amps out of the batteries then they would like. So the voltage drop of those batteries is pretty severe and causes the lv to trip in your controller. It stutters because as soon as you hit full throttle, the battery v drops, controller shuts of the system, batteries regain voltage, system starts woking, voltage drops, controller shuts off system, and repeats this very fast (ie the stutters).
I spoke to Chris at TNC Scooter and he said the problem is my 500 watt motor. He said a lot of these motors are 24 volt even if they say 36 volt right on them. He thinks that if I move up to a 750 watt 36 volt motor I should be good to go. By the way he is a great guy and really knows his scooters.
That doesn't really make sense to me. When you give a motor too many volts it doesn't usually stutter.. they do some other things, but stuttering isn't usually one of them. EB's reply makes more sense. What is your battery setup?
My battery set up is the exactly the same as stock, except I added one 12 volt. I put the front tire of the bike against the wall last night and gave it full throttle with a volt meter on the battery pack. It never went below 45.8 volts. The controller directions say it will cut out at 42 volts, so I'm not going below that at WOT. Hummmm?
Ah ok, maybe I'm wrong then. I guess it could be arcing or something strange going on inside the motor. I've never seen that before even with more than double voltage on a 24v motor.. but all motors are different.
What controller are you using? If you are using a controller that's rated 50amps and over, I'm absolutly surtain that the voltage of you 12ah lead-acid pack is sagging below 45v.
When I switched my batterie from my stock 12ah pack to a larger, more robust 18ah pack, my problem stopped and I still had the 36 or 24v motor in it. So this might just be sales-pitch by Chris even though a 750w would increase performance (but not stutters). Tell chris to send you 4 12v 7ah batteries to parrallel to your existing pack. This would decrease voltage sag dramatically as the lod is spread out more evenly and kill the stutters.
Edit: That was the solution for me.
Last edited by electricbike : 11-14-2009 at 02:16 AM.
If the stuttering is because the bats cant hack the amps, you can lower you amp limit by grinding on your shunt. Or you can ditch the lead and pony up for some better batteries.
14ah? Stock mx500 batteries are 12ah. If you added a 14h battery in series as the extra battery , it does not make the pack 14ah.
Adding the 48v 7ah pack in Parallel to the existing pack, would increase the batteries capacity from 12ah to 19ah and keep the batteries voltage to 48v. You charger is based on voltage, not capacity so it would do just fine. With a 19ah pack, you would not have stutters.
You would not notice the weight of the four 12v 7ah batteries as they are relativly small. The weight of those four 7ah batteries is the same as two of the 12ah batteries in your bike. Im sure you could find room in your bike for them; mkroberge got eight 12ah batteries in his!
All im trying to say is, that it's not your motor that's causing the stutters, it's something else. I suspect it's the battery because that was the problem and the solution for me.
What kind of batteries do you have? Are they rated for EV use? Not all batteries can be run at 50amps. You can have two the same size and same 20hr ah rating, and one will do 50a and the other wont. You should be a little more free with the details if you want real help. List everything you are working with.
It could even be something stupid like a wiring problem.
I did some more testing witht the volt meter on Sat. with the bike on the road and the volts did drop below 42 when I was moving. I then wires up another battery and now my stuttering is gone. I now have five on that little sucker now, 60 volts. The motor gets real warm but it hauls *** now. I figure when the 500 watt motor takes a crap I'll pop in a 750 watt 48 volt motor.
Don't be surprised if the motor outlasts the bike.. or when it at least outlasts your controller! From what I've seen they do fine up to double the volts. Just don't thrash it too hard and it should be fine.
My little 500 watt 36 volt motor is getting killed with 60 volts running to it (it does haul *** though). It smokes real bad when I run it hard and stinks up the garage when I park the bike. Do you think guys think I should go with a 36 or 48 volt 750 watt motor. I know the 36 volt will be faster but I don't want another smoker.
Lmfao. That burning is the red hot wire inside burning up the enamel. It's gonna go any second now. Run it till it dies LOL. I've ran a 750W motor at 60V. Hauled ***.
It actually never died, it just got so hot everything started melting (Worked darn fine though). Decided to tear it down and replace the wire in it for larger gauge with less turns.
The stuttering can be traced to thin wire. Thicker wiring is needed.
The stuttering can be traced to thin wire. Thicker wiring is needed.
Mine was beacause when I ran the bike at 48 volts it would jump below 42 volts at full throttle and the controller would cut the power. Running the system at 60 solved the problem because the battery packs would never go below 42 volts at full throttle. Was that 750 motor you ran at 60 volts a 36 or 48 volt motor?
its not the motor size or wire size, its the controller, i have this in my bike and it stutters.. its because you dont have enough amps and hr. i have 4 12v 12a 20hr and jerks/stutters after a minute or two i also run a 48v lb37 controller a little slower off the start but same top end with no stutters
My stuttering is all gone with the 60 volt pack I run now. It's just that the little 500 watt 36 motor runs real hot to the point of a little smoke out of it after hauling a** around on it. I thought if I put a 750 watt 48 volt motor in the bike it would handle the volts a little better and still have some of the high rpms (not as high as the 36 volt motor) since it's still over volted.
This thread is an excellent real world example of how much sag effects performance.. a 48v saggy pack doesn't really give you 48v when it counts. It gives you maybe 39 or 40v at wfo. So one is forced to go to 60v to get similar performance as a stiff 48v pack would provide at 50 amps.
