Small Hub Motor for a Small bike?

[Dauntless]

http://arthurpage.wordpress.com/2008/06/06/electra-voy-phantom-4-electric-moped/

What I really like about the Voy Electra is that they made it a REAL bike, even if it's small and for kids. It carries all 200 pounds of me up to 17mph, if you believe the speedo as many don't. Not sure what they cost new, mine cost pocketchange because it wasn't working.

What I marvel at is that the 180 watt hub motor is better than the 250 watt hub motor on my eCycle Dashes, which are better than the 350 watt Currietech, etc. All that speed and range at 180 watts????

So the Voy is the inspiration for a build I wish to undertake. Using a 16" wheel bike, available for $5-10 at garage sales because they don't look good enough for a parent to want it for their 4 year old, I wish to configure my own with a larger hub motor, perhaps 300 watts. That would get me up the hills coming home. I also need something easier for a big guy like me to pedal. At the mention of my name, the hills would then tremble.

What I need to understand is about the possibility of an AC hub motor. I find conflicting opinions online of what the Voy really is, AC or DC, brushed or brushless. The performance makes me think it just has to be AC. Could such a wheel be available?

If not, maybe there could be a 300 watt AC motor I could use with the bicycle wheel.

These are all just the right color, mine's red.

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[dogman dan]

Likely it's DC brushless. The starting point is going to be finding out what it's wattage really is. Ideally with a wattmeter between the battery and the controller. At least, if there are markings you can decipher, by taking the actual amps the controller is set for, and multiplying by the actual voltage of the battery.

Bet it's more than you think. The small wheel does really improve torque, but only more watts is more power. Lots of ES folks are loving 3000w-6000w on 20 inch wheels.

 

[fechter]

If you look at the existing motor, see how many wires are coming out if it.
A brushless (AC) motor will usually have 3 heavy wires and 5 smaller ones.
A brushed (DC) motor will usually have only two heavy wires.

Before replacing the motor, you might try running more power into the existing one. If it burns up, then you can replace it. Increasing the power usually involves getting a higher powered controller and/or increasing the battery voltage. Replacing the controller requires some messing around to figure out the wiring and if not done properly can blow the controller, so requires some skill.

If you're really cheap (like me), it may be possible to increase the existing controller's current limit by modifying the shunt resistor inside. If you try to increase it by too much, the controller will not survive, but if the alternative is to replace it, you don't have much to lose by trying.

With the existing setup, you can touch the motor and controller after riding up a hill to see how hot they are getting. If they are toasty, then you probably can't get a lot more out of them without smoking something.

 

[Dauntless]

Well, there's soft tubing/conduit around the wires as they come off the hub. From squeezing it with my thumb I'm thinking I feel 4 wires. Don't want to cut it open just yet. The other end runs to a junction, hard to say what's happened there without cutting it open.

(I've dabbled with the shunt on a 350 watt Currietech, the problem is it didn't mean much. I had a 600 watt Currie that was quite a bit better but not ENOUGH better, the 350 watt with a heavier shunt and an extra 12 volt battery didn't match the 600 watt. The 180 watt Voy is at least close to that 600 watt Currie. I'm guessing that a 300-360 watt version