Hi all,
Recently, my C-124 started reducing power occasionally while on my daily commute (9 miles each way). Today it died on me for a few minutes and I noticed that the dash LED was indicating 2 short and 3 long flashes, suggesting (according to the manual) that the power leads are overheating. However, after 3 minutes or so, it started up again and I made it the rest of the way home (just a mile or so).
Now, I did change the wheel out a couple of weeks ago because my bent rim needed replacing so I'm not sure if this could be related to how I re-installed everything. However, CurrentMotor had provided me with some really nice instructions so I was being pretty careful about re-connecting everything. I did check the lead connections on the controller tonight and they seemed tight.
Anyway, I was wondering if anyone has experienced anything similar or has some ideas on why they might be getting hot.
Cheers,
Jeff
I don't have any experience with a C124 scooter, but I would consider the following:
- where is the power cable temp sensor located?
- does the fault actually occur during conditions that would cause the cable to heat up, i.e. high amperage draw for prolonged time?
- can you reproduce the error by deliberately driving in a certain way?
- did the "reducing power occasionally while on my daily commute" start immediately after your rim repair?
- can you measure the temperature of the power cables? If yes, then you might be able to determine which cable is causing the trouble.
Increased heat in a cable is caused by increased resistance, possibly due to a poor connection or maybe a partial cable break from bending it too much. If it gets really hot, you might also see bubbling or discolouration of the insulating plastic cover of the cable, and notice smoke or smell.
This information may be used entirely at your own risk.
There is always a way if there is no other way!
Hi Mik,
Thanks for your reply. I managed to get a word with Terry the tech guru at CurrentMotor and he suggested that I look at the temp sensor, as you mentioned too. On the C-124 it's attached to a couple of wires that are basically pushed into the wheel hub at the axle, so all I should need to do it pull that out and for now will try replacing with a 1000ohm (quarter watt) resistor - until I can get a replacement.
I'll report back how it goes...
Cheers,
Jeff
Jeff Holmes
Wheels: Current Motor Co C124
Work: Encyclopedia of Life www.eol.org
Now that you know where the temp sensor is, you could measure the temperature with an IR thermometer, just to be sure to be sure....in case the temp sensor is sensing and reporting actual heat.
Unless the Tech can assure you that this (= a failed temp sensor giving false high readings) is a common failure mode, you need to be sure that the temp sensor is not reporting real heat.
This information may be used entirely at your own risk.
There is always a way if there is no other way!
I don't have an IR therm. but tried a test run with one of those meat cooking thermometers. I went about 1 mile and the max temp seemed to be around 99F. It did get up to 111F when I stopped back at home but then started falling again at rest.
Anyone have an idea what these power cables would run at normally? I can imagine they get warm under power but don't know what is reasonable.
Cheers,
Jeff
Jeff Holmes
Wheels: Current Motor Co C124
Work: Encyclopedia of Life www.eol.org
So I went for a more extended run (9 miles) and monitored the temp along the way. Never got over 100F except when I stopped at the end. Then it peaked at 110F and fell back down. Just talked to Terry as well and he let me know those temps are normal. He also said that the power won't be reduced until the temp in the cables reaches at least 140F. He is kindly sending me a new sensor next week. Thanks again Terry!!
Cheers,
Jeff
Jeff Holmes
Wheels: Current Motor Co C124
Work: Encyclopedia of Life www.eol.org
I don't know how to use a meat thermometer to measure cable temperature. Sounds potentially dangerous.
Make sure you do not pierce the insulation and zap yourself.
This information may be used entirely at your own risk.
There is always a way if there is no other way!
Likewise, you may be getting spurious LOW temperatures on your thermometer because of poor contact with the surface you are measuring. That's why the IR thermometer was suggested. Your hand is also a good sensor. 140 Deg feels very hot, but not frightening.
Look closely at the wires and any/all connectors for signs of excessive heat: melting, charring, distortion.
CuMoCos use of a thermistor to monitor power lead temperatures at the motorhub always seemed to me to be relic of over-caution from earlier product development days.
And Mik, the only way a shock is possible with DC would be if one completed a circuit through one's body to the negative pack terminal of other negative polarity part of the power circuit - and at about 80 volts, it needs to be thin and wet or cut skin to be dangerous. This is unlikely.
My C124 still has the loop of slack motor leads that was used in early "test pilot" scooters. This allows me to change a tire without making any electrical disconnections at all.