NEM0 - <$1k Electric Dual Sport

[Jay64]

I know you said you found one, but just for others reading along, they sell them cheap at Harbor Freight.

[captainslug]

I know you said you found one, but just for others reading along, they sell them cheap at Harbor Freight.

I actually got the best deal on a spring-retracting reel via Amazon.

http://www.amazon.com/Alert-Stamping-92 ... 666&sr=8-8
Ended up being $26 shipped.
Any reel you get will probably require that you change out the connectors since you'll be best served by having the NEMA 5-15 male end as the one fed out of the reel. I happen to have an extra plug in my parts bin.

[captainslug]

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

[captainslug]

Vinyl dyed it black, then changed out the connectors on the retractable cord reel.

Remade the arm for the chain tensioner. Drilled and cut a 40-tooth front sprocket.

Installed the cord reel in the now empty slot in the battery rack.
Made new footpegs out of steel bolts and aluminum.

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.

[gwhy!]

This is looking really nice... great job. Do you have any specs for the weight of the rolling chassis before all the electrics were fitted.

[captainslug]

This is looking really nice... great job. Do you have any specs for the weight of the rolling chassis before all the electrics were fitted.

It weighed 90 pounds (frame, forks, swing arm, and wheels) when it arrived in January. I've added roughly the same amount of steel I cut off.

Current total weight should be around 210 pounds. But I still need to get around to actually weighing it.
In all previous tests performance was comparable to a 70cc bike.

[captainslug]

I give up.
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.

The bike is too heavy. The motors are too small in wattage for the weight. The batteries don't have enough capacity.
All of the above issues could be resolved with a larger pack of lithium batteries, but I'm not wiling to spend that kind of money right now.
And I can't afford to work on this project any further for the time being.
http://www.youtube.com/watch?v=XrN3vfft_bs

[vanilla ice]

From your vid, I'd consider it a success if it were mine. After all it is only a moped. At 35 would be an illegally fast one in CA I might add! I'd ride it as it sits, hammer those cheap bats with miles until they die. At that point look at replacement options. Its somewhat difficult to build an expensive ebike, much more so to build a cheap one.. I think you've done awesomely.

[captainslug]

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.

[gwhy!]

From your vid, I'd consider it a success if it were mine. After all it is only a moped. At 35 would be an illegally fast one in CA I might add! I'd ride it as it sits, hammer those cheap bats with miles until they die. At that point look at replacement options. Its somewhat difficult to build an expensive ebike, much more so to build a cheap one.. I think you've done awesomely.

I totally agree.

[captainslug]

It likes mud

[TylerDurden]

I think you've done awesomely.

I totally agree.

+1

[captainslug]

Just wanted to note that the freewheel ate itself this evening. I'm going to have to weld it solid because it's no longer functioning properly and I don't have any way of removing it without also potentially destroying the freewheel adapter.

So word of warning for future builders: freewheels can only handle so much torque and temperature abuse.

Thankfully the motors are not terribly resistant to coasting, so the difference in performance will be marginal.

[recumpence]

I have pushed 20hp through a White Industries freehwheel without any problems! Of course, that is a $75 freewheel.

Matt

[liveforphysics]

Taking apart the ENO you find 3 big wide strong paws and deep pockets for them to sit. Take apart a $10 entry level Shamano BMX freewheel with 2 little paws each about 1/2 the thickness of the ENO paws, and sitting in shallow little indents.

I think the torque handling difference could be as great as 5x more with the ENO freewheels.

I would definitely look into getting one.

Great project! If the motors aren't overheating, start saving up for some LiPo, which should solve the weight problem, the power problem, and the endurance problem all in 1 neat upgrade

[Robomaniac]

I really like what you did!

Can't wait for "NEM0 2 - >$1k Electric Dual Sport"

[captainslug]

Quick update after I took a long break from this project.
I would like to retest this bike at 60 volts, but first I need to install a much stronger freewheel.
I managed to grind down and remove the motor linking sprocket, found the previous destroyed freewheel, and remove it from the freewheel adapter.

So next I need to
1. Order this freewheel

http://sickbikeparts.com/catalog/produc ... ucts_id=62
2. Attach a sprocket to it at the right spacing
3. Install it on the freewheel adapter
4. Make a replacement motor-link sprocket
5. Reconnect chain drive
6. Swap out the battery charger
7. Reinstall 5th battery

[captainslug]

Good news: I found the original footpegs and thefront brake rotor in a box at work.
I reinstalled the rear foot-operated brake which will give me more control and safety. Especially when the roads are wet (when front brakes are almost useless).


Now I just need to buy a new freewheel and get the chain drive back together.

[Thud]

How did i miss this build?????

Very nicely done CS.
I read through a couple times looking for the doner chasis make. Is it some china import?
great job on the lighting & fit. I like everything about it.

[captainslug]

I've ordered a 2.65HP treadmill motor to be used as hopefully the last and final power plant for this project. Its rated for 2.1kw peak, 1.6kw constant @ 95VDC.

And here's what I eventually want the frame to look like. Whenever it is I can get around to painting it.

I read through a couple times looking for the doner chasis make. Is it some china import?

A very chinese Xmotos XB-31XT.

[captainslug]

Motor arrived today. It's the perfect size, weight, and ratings. It also includes a hall effect switch for monitoring RPMs which will be very useful because I will need to use that in order to select the right gear reduction ratios.

I will test it at 60 volts with the controller tomorrow.

This motor spins so smoothly I'm contemplating not bothering with a freewheel. If I do ditch the freewheel I have the option of later adding motor braking of some kind (regenerative or not).

[vanilla ice]

Sweeeet, how much was it?

[j3tch1u]

fantastic build--one of the best i've seen. you should take that to production!

[captainslug]

Yesterday I removed the pair of motors and started work on designing the revised motor mount.

I'm waiting on a laser tachometer to arrive in the mail so I can measure the peak RPM of the motor at 60 volts. Then I can determine what reductions are needed.
The drive shaft of the motor unfortunately has a mix of imperial and metric dimensions. The tip is left-hand threaded 1/2-13, but the rest of it is 17mm.

I'm probably going to end up making a V-Belt pulley for it from scratch.

Edit: And now I have the motor mount finished.

Sweeeet, how much was it?

$90
Used treadmill motors are very easy to find at reasonable prices. This one was brand new and unused.

fantastic build--one of the best i've seen. you should take that to production!

Thank you very much.

[captainslug]

Motor-mount finished and assembled. Can't do much else until I have a tachometer with which to measure the motor with.

However if the tap arrives in the mail today I will be able to finish the custom drive pulley.