Problem with generic hubmoter kit

[sethmasia]

I bought two kits -- a 250 watt 36v kit for my wife's old steel Miyata frame, and a 1000w 48v kit for my old Bianchi klunker. Installation was straightforward. My wife's bike runs beautifully and she uses it for shopping trips two or three times a week.

On the 48v system I didn't bother to connect the pedal-assist input, nor the power-interrupt brakes.

The 48v kit ran well for a half-mile uphill test. But after I shut it down, it would never again power up. No power-meter LEDs, no response to throttle.

• I measure 53v at the leads into the controller. Good continuity through the on-off switch on the throttle.
• Got a replacement controller under warranty. No help.
• Replaced the throttle with a brand new unit. No change.

So I think I'm reduced to testing voltages and continuity at the leads through the hub motor itself. But I don't know what those values should be.

Seven wires involved: Four control leads (black ground, red power, yellow and green), three power leads (blue, yellow, green). What should be the values for voltage and resistance through the combinations?

Other questions: Is there a voltage limiter? Does the system shut down if it senses more than 52v for instance? If so, why did it run on initial start-up?

Perhaps a similar issue has been dealt with elsewhere in this forum, but I can't find it.

The vendor is in Hong Kong with a warehouse in the LA area. Shipping on the original kit took only a couple of days. They have been responsive (they did send a replacement controller, from Hong Kong -- took two weeks) but can't provide any sort of technical support, even in the form of an internal wiring diagram for the motor.

Any helpful ideas? Thanks in advance.

 

[flymeaway]

Any helpful ideas?

After changing the controller you still don't receive any power on indication? No LED's? Is the controller a separate component from the input device? If it is, there are only two possibilities, a bad input device, or battery. Measuring voltage without a load is OK unless the battery or BMC can't handle any load (amperage). Measure the amperage output (note: follow instructions on the multimeter used exactly!! Do not deviate from the instructions) or if you can, try another battery (best option)

Court J.

 

[sethmasia]

Thanks for the response, Court.

Correct -- after changing controller, no change in system behavior (or in this case, nonbehavior). I can measure amps between battery and controller. How to measure amps between controller and hubmoter, given that there are three power leads? What do you mean by input device? My components are throttle with three leds for battery level, controller, battery and hubmotor.

 

[flymeaway]

What do you mean by input device?

Depending on the kit there is often an LCD screen with input switches and an on/off switch separate from the throttle. If you are able to measure amperage between the battery and the controller that should be sufficient to confirm the battery can power under load which means at the minimum without powering the motor you should see the battery LED. Since you've swapped out the only two components between the motor (throttle and controller) and you can get an amperage reading between the battery and controller but still have a dead system you've done everything short of replacing the motor the only other possibility is the items you didn't install. Without knowing what the the kit is, try plugging in those components and see if the bike will power on you don't have to actually install them on the bike, but there may be a need to at least plug them in to complete the circuit.....I'm assuming you did try it (plugging them in)????

Court J.

 

[sethmasia]

I get .001 amp (10-amp DC setting) between the battery and the controller, with of course no increase when I twist the throttle.

Will repeat amps test with the cadence sensor plugged in, but I've already tried to run it with that sensor plugged in with no joy. Remember that this system ran just fine for 300 yards without the cadence sensor and brake cut-offs installed, and then died when I turned it off.

 

[sethmasia]

Attaching the cadence sensor makes no difference. Same amperage reading.

 

[sethmasia]

More data -- the system works! But only with the ammeter in the circuit between the battery and controller. .078 DC amp with the throttle switch on, 1 amp and up with the throttle advanced and the motor spinning. 53.6v to the controller. As I understand it, the ammeter shunt imposes a tiny voltage drop -- why should that make a difference to the controller circuit?

 

[sethmasia]

I hooked the battery to a 40w AC incandescent bulb and discharged it to 52v, then put everything back together. It works! So it was a battery overvoltage issue. Wish there were some kind of warning for that. I'll have to figure out a way to monitor future charge-ups to make sure I don't go over the controller's voltage tolerance.

Anyway, we're in business and I'm happy with the way the bike runs.