Simple (sorta) XtraCycle build

[Skunkeye]

Hey, guys! I've been reading these forums for quite a while now, absorbing as much e-bike information as possible. Last year, I finally broke down and bought one of cell_man's geared rear-wheel kits and a Ping battery for my cargo bike. My original intent was to hack up a "Stokemonkey" style mid-drive, but I realized I don't really have the time right now for a build that complicated, so I finally (after having all the parts just sitting for several months) broke down and slapped the motor on as-is. My intention with this bike isn't really to blow anyone's doors off, anyway, it's just to have a little help with the hills and headwinds (and heavy cargo). I built a custom battery box to replace the XtraCycle deck and stuffed in a 36v 10 Ah Ping pack, along with a Turnigy watt meter to keep track of the electrons. The controller is bolted to the bottom of the battery box, so the whole effect is pretty stealthy, with most of the good bits out of view.

So far, I'm pretty pleased. With a moderate amount of pedaling and a load of groceries or the like, I get about 12-13 Wh/mile. Longest ride so far was 22 miles, and I think the battery still had a fair amount of juice left. The only outstanding issues are the chain (it scrapes and rattles on the chainstays in the high gear), and rigging up some kind of cutout switch on the rear (disc) brake. I've rigged up a guide sprocket to manage the chain, but the chain jumps off it during certain gear changes, so some tweaking is in order there. Also, the controller has an extra blue wire (bullet connector), the purpose of which eludes me...

Anyway, just wanted to thank the whole community here for the incredible wealth of information you've provided. The only problem is, when you're starting out from scratch, there are almost too many options...

[Xanda2260]

That is some fine work sir! Loving the snap deck replacement with built in battery - beautiful!

Welcome to the forum proper

[rojitor]

Welcome to the forum! Nice cargo you got there, i love the flash

[BikeFanatic]

Very nice, I love that deck. I wonder if you could post a pic with the deck open? I can't believe you can fit a ping in there.
I have an Xtracycle as well and no one suspects it is electric until I buzz by them at 25MPH.

[Skunkeye]

I had Ping build the battery as two separate packs, wired together with one BMS so I could get it all to fit. Each pack is about the size of a large paperback book, so it all just barely fits in the deck (I wanted to retain the same size and shape of the original deck as close as I could). The nice thing is, I don't give up any cargo space at all to the electric system, since I can still strap stuff to the top of the deck, or have a passenger back there or whatever, and the bags are completely empty.

I'll try to post a picture of the open battery case this weekend.

[dnmun]

way cool. make sure you use really large wire to connect the two 1/2 packs together in series.

when the pack is producing a lot of current, the voltage drop on a small wire in that middle connection will cause the sense wire on the bottom cell of the upper portion to detect LVC prematurely. monster had this problem last year.

so use 10 AWG or more, and connect that sense wire to the middle of the connection cable so the voltage drop can be split between the two cells to minimize false LVC shut downs.

really pretty. a townie too. BOL, dm

[Skunkeye]

Sorry for the delay - I finally got around to popping open the battery case to take some pics. Not much to see, but you can see how the split pack fits inside for a relatively low-profile deck.