<$1k DIY Neighborhood Electric Motorcycle - Page 21 - Fuel Economy, Hypermiling, EcoModding News and Forum

Christ · 09-24-2009, 01:42 PM

So there was never a need for two freewheel adapters, right?

I mean, the only necessity for a freewheeling sprocket was to allow the wheel to spin (thus allowing the chain to continue it's path) without keeping the motors spun up, right?

You may have covered this, but why didn't you add a freewheel to the rear sprocket?

captainslug · 09-24-2009, 01:49 PM

Quote:

Originally Posted by Christ

So there was never a need for two freewheel adapters, right?

I mean, the only necessity for a freewheeling sprocket was to allow the wheel to spin (thus allowing the chain to continue it's path) without keeping the motors spun up, right?

You may have covered this, but why didn't you add a freewheel to the rear sprocket?

I had two because the first drive chain loop setup covered both motors.
There's no space or a feasible way to add a freewheel AT the rear wheel. So the freewheel has to be on the motor.
Freewheels gain me an increase in range (through coasting) comparable to what I would receive by having regenerative braking, but without the cost of having a more sophisticated controller.

The solution I've come up with to mechanically link the two motors is to buy two small #35 sprockets, then drill and tap their bores to match the thread on the end of the drive shafts.
I will then have to make adjustments to the motor mount plate to update their spacing to be in line with each other and the rear wheel.

-$40

captainslug · 09-30-2009, 06:14 PM

Drilled and tapped the small sprockets to M12-1.75. The one on the lower motor will have to be tacked in place to keep it from backing off the thread.

Measured again and then modified the motor-mount plate.

captainslug · 10-01-2009, 05:02 PM

New power train works great.

But the bad news is that the motors are still getting very hot at speeds above 20mph.
I feel like I'm out of money and out of ideas. As a last-ditch effort I may try to water-cool the motors, since I already have the supplies to do so. Doing so just unfortunately complicates the bike more than I really wanted to.

Daox · 10-01-2009, 05:35 PM

What about some ducting to direct air to flow over the motors? Since it only gets hot at higher speeds, the ducting would become more effective when the motors need it most.

MetroMPG · 10-01-2009, 06:10 PM

Just got caught up on this thread, Cap'n. Continually impressed by your workmanship.

Also: will try to keep your determination in mind next time I run up against a roadblock in whatever things I'm trying to kludge together

captainslug · 10-01-2009, 09:19 PM

Scratch my previous pessimism. After I get the temperature monitor installed I will hook up the battery pack at 48 volts and see if the controller can handle the lower voltage. If it can I would like to do some test runs at that voltage and see if the motors stay a more reasonable temperature.
If the controller doesn't like 48 volts then I'll source a cheap one and do the tests.

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.

Christ · 10-01-2009, 10:00 PM

"Attaboy" for you.

As always, great update!

captainslug · 10-07-2009, 04:46 PM

Temperature monitor is installed.

And the charger is swapped out for a 48 volt model.

I can do some test runs tomorrow.

captainslug · 10-08-2009, 01:27 PM

Bike is 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, 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.