Having now ordered all the parts, I thought I'd sort out some of the bits that usually get left till last, like wiring, connectors and all that messy stuff. I hate messy wiring on a bike, it just makes the thing look a bit Heath Robinson, plus it ends up getting dirty and is hard to clean.
The Swift design presents a few challenges when it comes to mounting stuff, so I have decided to fit the controller and battery in the same box, and fit that vertically to the handlebar stem. This leaves the seat post free to move up and down to allow the folding mechanism to work, something that would be harder to do if I fitted the battery to a seat post rack (as I've done on my current folder). I also decided that I wanted a way to quickly and easily remove the battery pack for charging, without needing to unplug wires. Putting the controller and battery in the same box eases some of the messy wiring problem, but I still need to connect a fair few wires between this box and the bike, the three phase wires, three Hall wires, +5V, 0V and the throttle wire, plus, maybe, a lighting wire.
I'm only going to use a small battery on this bike, as I don't need more than around 10 to 15 miles range. 222 Wh should be fine, as my current folder only uses around 15 Wh per mile and this one should be a bit better. I've settled on just two 6S, 5 Ah Zippy packs. These are small enough to charge on a low power charger through the balance ports, so I also need to bring out 13 connections from the battery pack to connect to a balance port charger.
So, in total I needed to bring out three high current phase connections, plus about 18 other connections. I decided to have a go at making a connector that would connect simply by dropping the battery/controller box into a cradle fitted to the handlebar stem. I have to say it worked rather well. I cut out a couple of bits of 1/2" Delrin, milled some slots to accept DB25 connectors for the low power connections and drilled holes to accept RC type barrel connectors for the phase wires. One of these two bits of Delrin will be fastened to the bottom face of the alloy battery/controller box, the other will be fastened to the bottom of the cradle that holds it. To remove the battery for charging (or security) I should be able to just lift it out and the connectors will just pull apart. Here's a photo to show work so far:
The box that will house the controller and battery is the shiny thing under the connector, laying on it's back. The bottom face will be the one to the right of the photo. The box is about 2 1/4" deep and will just fit the Zippy packs inside with "just" enough room for a 6 FET controller and the wiring, plus some other gizmos. On the top face of the box, which is about 5 3/4" wide by about 2 1/4" deep, I plan to fit a display showing capacity remaining, power, voltage, current etc, a bit like an ordinary wattmeter, but with a memory, like the CA, so the pack can keep track of itself.
To charge the pack up I'll build another of the simple foolproof chargers I made for a friend, that will have a multicore cable that connects to the battery balance ports via the DB25 connector. I'll probably also make up a lead to connect this port to a Cellog, so I can occasionally monitor individual cell voltages to make sure things are looking OK.
The frame, motor etc won't arrive for a fair while yet, I expect, as all freight into the UK from abroad is being held up by the Olympic security stuff, apparently.
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