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Old 04-24-2016, 12:58 PM   #1 (permalink)
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Join Date: Sep 2012
Location: Victoria, BC
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Firefly EV - '98 Pontiac Firefly EV
90 day: 107.65 mpg (US)

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90 day: 33.35 mpg (US)

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Turtle My electric bikes & projects

Thought I'd start a thread, since there seems to be no end to my electric scooter/bikes. They tend to come to me in various states of distress, and those which don't, end up in such a state pretty quick.

Really, I love battery-electric powered doo-dads that do something useful and enjoy working on them, and I like the freedom of riding without a cabin/cage around me, so it's no wonder I keep coming back to these and jump on any good deals that come my way.

Let's start with my original, a Luyuan electric scooter(that conforms to Canadian electric bicycle laws) sold around hear a decade ago as a "Green World EV":

...complete with my kid, when she was 3 years old. That was a while back. That's one of those child carrier seats, and I built the bar it sat upon, so she would be in the safest spot. She and I, or she and my wife, rode around four a couple of years like that, until she outgrew the seat.

Bike was neglected. Batteries were pretty weak, but it was a starting point.
The 48v, 350w motor went nicely, until you got on an above-average incline, then it would grind to a halt. Wasn't long before I modified the controller to permit more current. It worked quite well, but the already weak batteries didn't survive long. I would still use it for short trips, but the range was non existent after that.

I don't seem to have any older pics of my second one, that came a few months after the first. It's current state can be seen here beside the blue one, where they currently sit "decommissioned":

I traded a motorcycle that I got on the cheap for it and fixed up, when the carbs on said motorcycle started acting up again and I got fed up with it...

It too is a Luyuan/GWEV, but has a 500w motor on it instead. It had good batteries, and since the bike was identical in all but running gear, the battery fit the blue bike as well. Hence how I got a couple of years out of the blue bike. If I went with my daughter, we'd take the (slower) blue bike. And if I was going out on my own, I'd take the more powerful black & silver.

Being greedy or some such, I tried modifying the controller for the black one, but at some point I screwed up and fried it. I recall shorting something out on the board with a screwdriver or a screw or something when testing it out after, and I probably fried the 5V bus. One year, I'll get around to trying to fixing it.

Instead, I dropped a new 1500w, 72v ebay controller in to it and had fun getting the phase/hall wiring right and rewiring the bike with heavier wiring and a switch setup for dual voltage - 72v & 48v, because it would go illegally fast on the road at 72v. It did about 45km/hr on level or slight inclines, and more with a downward incline. It was fun, but I only got a couple of uses out of it before the battery selection switch fried. Apparently, they're not built to withstand the intense discharge of all those capacitors in the bigger controller when dropping from 72v down to 48.

I replaced the switch, figuring I'd just be more careful/give the capacitors time to self-discharge before switching, until I felt like adding some minor circuitry to prevent it. Well, the new switch didn't hold up well to the large current flowing through it, and also died within a couple of rides. It was late in the season, so I just packed it away and satisfied myself with the blue one instead.

I mentioned rewiring it. This was the instrument cluster I put together when I did that:

Active voltage, current (100a shunt mounted under the leg shield), and a much more accurate speedo...since the new controller didn't have a speed output to run the old, inaccurate one. And it didn't go high enough, either.

It was nice to see exactly how much power was being sucked out of the batteries, which was up to 40 odd amps. The motor got luke-warm to the touch after a while, but that was it. Lost regen braking with the cheap controller, mind you, so slowing/stopping became pretty hairy.

As a side note, for those who don't can trick one of these motor controllers in to powering on in spite of being above or below it's operating voltage range by having a different voltage going to the power(on/off) then is going to the main battery input for the controller. IE, the controller circuitry was seeing ~72v, even though I was only feeding 48v through the controller to the motor. (if the FETs and capacitors were rated high enough, this could mean feeding 84v or 96v through the controller while the control circuitry only sees 72v)

Some day, I'll come back to this bike and/or re-purpose the motor. I doubt it compares well to modern ones, but it was certainly powerful and fast enough for my purposes.

That will do for the first post...

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