NEM0 - Electric Dual Sport Motorcycle
Temperature monitor is installed.
And the charger is swapped out for a 48 volt model.
I can do some test runs tomorrow.
I can get the same top speed at 48 volts if I switch the freewheel sprocket to 35 teeth instead of 30. But I need to find out if the voltage drop will resolve the thermal issues.
Being at 48 volts will also make it easier to upgrade to a lithium pack later on.
If your voltage goes down, but you keep asking he same effort from the motor (by requiring more torque by switching to a smaller sprocket), the motor will still go hot.
R has a point, just put in a bigger sprocket, you will lose speed at the same rpm, but lighten the load overall. bonus: you'll have more torque at the wheel.
The overheating issues were not because of current, but because at higher voltages I was reaching RPMs that the brushes could not handle.
Bike is currently running great. Temperature sensor is indicating that the motors are not getting above 120F, even at top speed.
Next I need to change the front sprocket so I can increase the top speed from 29mph to 35mph, and I would like to make a storage box for the charger cord that will fit in the upper most slot in the battery rack.
I've ordered the relays I need to make the motor wiring adjustable from a toggle switch on the handle bars that will control a pair of relays.
Doing this will give me a 2-speed manual electric speed selection.
Series wiring will be used for acceleration. Parallel will be used for top speed.
Doing this should also GREATLY reduce the power consumption during acceleration without sacrificing any performance (since it will in fact give me more available torque).
I will have to do practical tests once the relays are installed to determine what positive effect the configuration has on range. I'm hopeful that it should be a noticeable increase of 20 to 40%.
Finally, a video of some sort. Albeit just one to show the drive-train.
http://www.youtube.com/watch?v=ndVJ5Ost25E
I was worried that the freewheel had seized, but thankfully it was just in need of some chain lube.
The wiring bucket is getting a bit cramped. Good thing everything is labeled.
I've added a relay to the charger connector so that the charger is disconnected from the batteries once the ignition is switched on.
This prevents the charger from drawing power from the batteries, and it prevents it from getting confused about the charge state once the charger cord is plugged into a 110VAC outlet.
The charger isn't very sophisticated and isn't meant to be onboard, so I have to fool it into thinking I'm plugging and unplugging it.
I used a leftover brake lever and a toggle switch which I made a mounting bracket for. This lever will control the relays to switch the motors from parallel wiring to series.
And here are the relays and the resulting hairball of wires
The battery rack mounting holes have been moved so that there's enough space to install a larger front sprocket.
Left to do
1. Drill/cut new front sprocket
2. Finish reassembly
3. Testing
4. Adapt and install retractable cord reel in the empty slot of the battery rack
Vinyl dyed it black, then changed out the connectors on the retractable cord reel.
Drilled and cut a 40-tooth front sprocket.
Installed the cord reel in the now empty slot in the battery rack.
And after a great deal of annoyance trying to fix the cut-off relay for the charger, it's working.
The bike can now be charged from the built-in extension cord or the gas tank plug receptacle.
I'm just waiting for my replacement drive chain to come in the mail.
The series-parallel switching relays are working as expected.
The 40 tooth sprocket just made things worse.
The Series-Parallel switching works, but the series mode doesn't offer enough torque to be very useful for acceleration.
Top speed in Parallel is only 18mph.
Top speed in Parallel is 35mph.
And the battery pack is struggling to supply the demanded power.
http://www.youtube.com/watch?v=XrN3vfft_bs
So I put the 30 tooth front sprocket back on.
2kw Parallel Top speed: 30mph
1kw Series Top speed: 12mph
Estimated range: 12 miles
Performance is comparable to a stock 50cc bike. I'll hopefully be able to weigh the finished bike soon.
And yes I've learned a great deal along the way.
Nice to see your project nearly finished... I still think that with a smaller front sprocket (or bigger rear sprocket) you will extend your range and cool down your engines... Actually you have experienced with the worst choice, you know, increasing the size of the front sprocket does not help at all your torqueless engines. ;-).
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FKing SHT! You cannot possible imagine how I hate speaking English so badly that almost nobody understands me... Why the hell nobody speaks catalan here???;-)
Let me try it again: captainslug, PUT in your bike what you see very BIG in this picture.
Just stay focus on the very very BIG thing in the picture that you have very very SMALL in your bike.
Do you get it? It's called big sprocket, I think!
That would not triple or quadruple the total cost of this build, would it? And the engines will remain cold as ice.
I hope this time you'll understand the idea I'm trying to tell you.
Do you like the idea?
cheers,
R