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Sunday, 9 February 2014

Failure at Golders Green

I had a great day planned. I was going to park near Golders Park, do a nearby cache, zoom up to Golders Green for the multi there, then cycle down to London and commit mayhem amongst many caches there.

It started off badly. I parked, got the bike out, loaded up two saddlebags with batteries, food, tools, and all the other supplies I might need for a full day in London, and cycled to Golders Park, where I totally failed to find the first cache.

After I gave up on that, I went to Golders Green. I'd already worked out where the final for the multi would be, so I went straight there, and there it was.

And then the bike started to play up.

It's either the motor, or (more likely) the controller. It would go for a few yards, then the motor would refuse to turn; the effect was as if the brakes had been put on, hard. I tried it a few times, I rebooted the controller, but eventually I decided to bike back to the car and open up the wiring, maybe water had got in, or there was a loose connection? Neither of those, and it just continued to misbehave.

And if I tried to use it with the motor switched off, I was getting a lot of drag on the motor wheel. So, no chance to use it as a non-electric bike.

So I went home.

I now have a fan heater on the motor, and another on the controller; maybe water has got inside? When I was out last week, I went through a very deep body of water, about a yard deep. I held the motor out of the water, but maybe not well enough? I don't see how I could open up the motor, and opening up the controller will be my next resort.

Meanwhile, I've gone to a web site I know and I've ordered a new controller. I ought to have a spare anyway, even if this one is OK.

 ... update ...

No water in the wiring. So I got a couple of fan heaters, pointed one at the motor and the other at the controller, and left them.

Mistake.

One heater is 2000 watts, the other is 3000, so that's 8 and 12 amps amps. The pair were drawing 20 amps from a 13 amp circuit. I had them on a long, coiled extension. The extension got hot ... very hot ... and blew a circuit breaker. That cut power to a dozen computers, and it was at that point that I discovered that I'd totally unbalanced my PSUs, so that one was doing almost nothing, and the other was doing almost everything. So the PSU ran down before I knew what had happened, and a dozen computers went down.

I rebalanced the PSUs, and got the computers back up again (which is quite a long process after an uncontrolled shutdown like that). Eventually, I had all the computers up and running.

So, what about the bike? The motor ran fine. So I took the bike out for a longish run, and it was still OK. My conclusion is that there's water in the controller, and the heat has gotten it out. I'm applying more heat (but not at full blast, only one heater, and not via a long coil of extension). I've sealed up the wiring again - I'm using an old plastic oil can, and then duct tape to seal it all in.

Next weekend, weather permitting, I'll try that London excursion again.

... update ...

The long coiled extension is dead. I examined it, a lot of the insulation has melted, and it's now dangerous to use as an extension. I've taped up the sockets, so it won't get used by accident. The reason I haven't thrown it away, is that most of the cable is salvageable, all I have to do is not use the melted bits.

So then I plugged the second fan heater into another socket, but now each of them is inline with an adapter that tells me how close to the 13 amp maximum they are (one is 4, the other is 6 amps). So that should be safe. I really shouldn't make stupid mistakes like that!

After the heating/drying process had been going for a while, I thought it would be a good idea to see if the motor was still running. I've been charging up the battery that I used for testing before, so I just switched the battery main power outlet to the harness that puts two batteries in series.

The balance leads immediately started to emit thick smoke. Uh-oh. What I'd forgotten, is that connecting the two batteries like that in series, while they're still connected in parallel via the balance leads, is going to send huge currents (probably more than 100 amps, although I didn't actually try to measure it) through the balance leads. I disconnected as fast as I could, but the parallel balance lead is now kaput. It joins the long coiled extension in my trail of destruction today.

Lesson learned. If I'd thought about it before I made the connection, I'd have worked it out. Probably. But for sure, that's a mistake I won't make again.

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