(Photo courtesy Jake Saunders)
The other bit of fabrication you need to tackle on a conversion is the battery mount. In most amateur conversions this is the least elegant part of the project- with all kindness, most builders put together some variation of steel angle-iron or box, and then cover it up with a fairing. My problem is my old buddy Bryce Larrabee. He’s a machinist and fabricator, and every time he sees an angle-iron construction he says it looks like a farmer built it. I can’t escape my early imprinting.
The other part of my problem is my basic notion of the beauty of a motorcycle. A pure motorcycle is a pure machine- one of the highest expressions of “form follows function”. A beautiful motorcycle is a design where everything is essential to the operation of the machine, and is honestly, and elegantly, presented. The batteries on an electric motorcycle are a huge challenge- it seems like there’s no way to make them look like big blocky afterthoughts.
One solution is the Brammo frame- it’s tied together with an extruded aluminum I-beam where the batteries sit. They’re using six Valence batteries, and they’re riding above and below that I-beam. It’s a logical solution, but the heaviest part of the entire build- the batteries- ride pretty high on the bike, making a fairly high center-of-gravity. This is the same strategy that Brammo uses on the Empulse- a naked-streetfighter/roadracing style, that is just awesomely cool looking for all the right reasons. Every bit is visible, and it’s all presented beautifully.
Another beautiful solution is the MotoCzysz design. Using smaller and more batteries- I believe they’re using the A123 cells- they assemble packs that attach to the main central core member, shown here.
This gives you something that looks like this, in full race trim- below.
Construction like this may be beyond the scope of an amateur builder- indeed, conceptualizing something like this is beyond the scope of normal mortals- something I don’t consider the designer, Michael Czysz, to be. There is simply nothing that I’ve seen that this guy hasn’t touched that isn’t brilliant- including his riding prowess, as demonstrated at the TTXGP this summer. But I digress.
The Czysz design inspired my own drawings to make modular battery packs center mounted, that could take various sizes and shapes of batteries, depending on what I decided to run at a future point. Here’s my mockup.
In practice, I made a rudimentary rack on my tube frame that allows me to clamp batteries in place. It’s made of aluminum, and can handle shelves, as shown here, that hold these AGM batteries, or lithium cells like Thundersky. It could also handle the packs I showed above, or an array of Headways. That said, it carries the batteries really high in the frame- although this bike weighs in at 250 lbs, (very, very light) the center of gravity is really high. If I added another 100lbs of batteries in this configuration, you’re looking at a really nasty handling problem.
I think one of the things we’re going to see in the coming years are some really resourceful designs for battery housings. Things like fast-switch packs, like what Zero is running, ultra-low battery mounts, integrated battery/frame designs- it’s of critical importance, and there’s a whole lot of room for improvement.
Oh, by the way- if you talk to any builder and they say they’ve never used zip-ties, duct tape and bungee cords to hold batteries in for the “test run”, as shown above from Jake Saunders’ creation… they’re lying. And duct-taping batteries? …an art all of it’s own.