The fancy fairing in front is both a fender for road spray and where I house the controller and switching deck. Being in the airstream there improves cooling for the controller
I was actually thinking of asking about it... the shape seemed so weird. My initial thought was that you had salvaged it from another bike, and that the electronics were mounted in the frame (which would have acted as a passive heatsink while also benefitting from the airflow while in motion).
It's funny, I didn't remember you were an engineer. Whether you are or not, you deserve a degree in my book. You've pretty much taken everything into consideration, which is more than I can say about the engineer who put a large, shiny, BLINDING BLUE LED on the power button on the front of my computer display (woe to him).
But I digress...
I agree with you that Lithium batteries are still too expensive, tho unlike you I tend to need much smaller batteries (and in greater number) to power robots and wireless sensors. This has led me on a quest to find cheap LiPo cells. And that quest, my friend, has been successful, so I'm sharing my results with you. First, however, I have to point out that your mileage may vary (pun intended) due to the fact that the Euro is currently stronger than the US Dollar, and that I've explored markets that may be very different in the US.
First, LiPo batteries are slowly but inexorably becoming THE battery technology for R/C aircraft modeling. It's the weight thing, obviously. a123, which I already mentioned, actually has products dedicated to R/C but they are very expensive. However it's very easy to find individual (3.3 / 3.6 volt) flat, naked LiPo cells that can be used to create your own battery. All dimensions are available, from postage stamp to postcard (and obviously thicknesses vary with capacity).
This American vendor has prices a Frenchman will consider cheap.
Second, look for clearance sales on car entertainment systems : I've recently bought a total of 40 Ah (7.2) of battery for around $150 dollars, at an 85% discount : these were external battery packs for now-obsolete portable DVD players. The great thing is, they are prepackaged, with a charge indicator, output regulation AND contain their own charger which you can plug on your car's 12V, so it's a lot more than naked cells.
Naked cells can be combined in series and parallel like any batteries HOWEVER this is serious, potentially harmful business. If you're interested, I can post how to do it safely. If you make your own battery you'll also need to add battery supervision chips to it for safe operation (i.e. avoiding over- and under-charge). A bunch of these chips can be obtained as free engineering samples from companies like Texas Instruments. If you can make a high-current motor controller, you will have no trouble understanding how they work.
In the end, you should be able to get your high-capacity batteries for less money, plus you'll get the freedom to shape them like you want. Me, I would place them AND the electronics inside the wheels, for four reasons :
- The basket area could be used for carrying something useful
- The rotation of the wheels will enhance cooling
- Wiring is simplified
- The wheels become heavier which should help with stability at low speed
Ah, and just for fun, you might want to have a look at this
really nifty hybrid car being considered by the US Army. With its wheels retracted, it will fit inside the belly of a V22 or a large helicopter. That wouldn't be possible without the in-hub electric motors and drive-by-wire.
Nefastor