Interesting failure. Guess what it is.

So, I was working on setting up my bike, and suddenly it doesn't work. Here's what happened:

I get everything all nice and running and test it. Works fine. I zip-tie the cords to the bike and saddle up with the backpack. I turn the throttle a little. A fraction of a second acceleration and then nothing. Needless to say, I was both pissed and confused. Everything had worked a few minutes earlier. It got even more confusing when I started testing things.

At first, I thought it was the throttle. I had similar problems with the first. The hall sensors signal and negative legs kept touching and stopping the motor. I opened it up and used a little hot glue to hold them in place. Got me nada.

I knew it couldn't be the breaker or Doc Wattson, because the Doc Wattson was giving its readings normally, and it's behind the breaker.

Worried now, I figured it might be the controller, or worse, my very labor-intensive wiring job. Unplugged the motor and attached a voltmeter to it's leads. Turning the throttle varied the voltage just like it should.

Now I'm starting to thing I did something terrible to the motor, somehow. I hooked up the voltmeter to it and spun it a little. Luckily, I got voltage out of it, so that wasn't the problem.

By now I'm almost completely at a loss, but I decide to go back to checking the wiring. Throttle signal is getting through. Voltage is present, so the wires have connectivity. Motor works fine.

I go through about every test I can think of, and eventually I figure out the problem. Guess what it is. I find it kind of interesting, actually, even though I have no idea how it managed to do this.

Brake cut off?

Nope. More unusual. As far as I know, I'm the only one here who this has happened to.

Zip ties cut a wire for an 'open' or squish the insulation enough to cause a short?

Nope. That would have resulted in a loss of voltage to the motor and the breaker tripping.

an insect crawled inside your motor and squished, shorting out the coils?

As...unusual...as that is, no.

Hint: Remember, I can get voltage at the motor teminals, and the motor itself is fine.

You plugged the throttle in a brake cut off thing?

You have voltage but no amperage.

Someone's dog urinated on your hub motor?

You plugged a brushed controller into a brushless motor?

You installed the motor in reverse ?

I'd bet EMF got it.

You blew the fuse?

Your motor connectors melted and fail to make contact.

Mathurin said:

You plugged the throttle in a brake cut off thing?

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I got voltage to the motor, so no.

kbarrett said:

Someone's dog urinated on your hub motor?

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I haven't the slightest clue how that would effect what happened, but points for the LULZ.

knightmb said:

You plugged a brushed controller into a brushless motor?

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Give me some credit .

Ypedal said:

You installed the motor in reverse ?

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That would have been a much bigger (and reproductively harmful) surprise than this.

OLIVIER said:

You blew the fuse?

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I don't even have them installed yet (have holders, but not fuses). I'm just hoping the little 14ga wire on the battery melts before I crash into anything .

TylerDurden said:

Your motor connectors melted and fail to make contact.

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A plausible answer, however it wouldn't have been instantaneous like this and the heat would have visibly messed up the plug and heatshrink.

EMF said:

You have voltage but no amperage.

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Full credit to EMF for his attention to detail and lateral thinking skills.

Partial credit to Mathurin for picking the person with the right answer.


Major bonus points to anyone who figures out how this actually happened:

After going over everything multiple times, I was too lazy to turn the dial on the DVM to "continuity check" and just flipped it to resistance. I checked the negative power lead. 0.00Ω reading. I checked the positive wire and...

WTF? Resistance > 200Ω? I practically flipped because this almost certainly meant something had happened inside my very tedious wiring job. Not only did I spend I long time putting everything together, I was out of 1" heatshrink. I couldn't put it back together if I tried without more heatshrink.

I go about looking for the problem by flexing the wire in different places and looking for fluctuations on the meter. Luckily, it was in the SAE plug that the motor plugs into, so I didn't have to do anything major to the throttle/power plug I put together. I had a couple extra, so I just put another on.

What befuddles me is how do you get a solid connection to go from almost nil to over 1kΩ resistance, instantaneously no less? Normally, I would suspect that the wire went bad inside and melted a little, but the connection wasn't consistent with that kind of failure. Normally, you would see on/off/little ohmage on the meter when flexing the plug. However, what I saw was the connection fluctuate between 400Ω and 1.6kΩ. It never went to zero and never disconnected, no matter how I twisted, pulled, or pushed the connection. Even more confusing is why didn't that happen when I was testing it? And why so suddenly?

:?

:? So, was the connection poor? Or was the wire defective or broken but still touching inside?

recumbent said:

:? So, was the connection poor? Or was the wire defective or broken but still touching inside?

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I don't know. Poor connections almost always result in a connected/disconnected thing happening when you mess with them. Maybe (though I've never seen it) a connected/disconnected/disconnected-with-a-little-resistance thing. I haven't the slightest clue how I ended up with a very-high-resistance-but-always-connected failure. Let alone when it worked perfectly before. I know it was internal at least, because it didn't matter where in the plug I stuck the DVM.

I recall reading about something like this on Power-Assist a few years back, a older bike with lead batteries. The wires weren't soldered on the terminals, instead they used those push on crimp connector things. It tested out flawlessly but just didn't work. Turns out the solution was to unplug the connectors, squeeze them with pliers and put them back on.

Those are fast-ons/quick disconnects. I use them, but they're all soldered on. Also this was on the SAE connector that goes to the motor.

Is there a prize giveaway after all that?

I suppose. Here's a little electronics-based ASCII art for EMF. Open it with Notepad or WordPad with wordwrap off if you have a low screen resolution.

http://h1.ripway.com/DeltaWound/ASCIIs/EMF.txt

Mathurin's partial-credit prize is that I upload mine, too.

http://h1.ripway.com/DeltaWound/ASCIIs/Logo.txt


BTW, why won't it allow me to upload a .txt file?

Let me guess. You forgot to charge your battery and it hit the LVC. Maybe it's the otherway. You hit the HVC and it won't move. Got too greedy?

Speaking of which i just dig up my 1000A Jump starter after forgetting to charge it for a year. It read something like 1.6V. My vector charger wouldn't even accept it. Had to jumper it with another 12v SLA and then start the charge. Got out the desulfator but don't know how many cycle and how long before it is back to working condition. SLA suck!