notvhere

I haven't put a rack on but I did do proper mudguards. Although there are tapped eye holes for attaching, I did find them a right faff to get to fit -- so much for the extra clearance around the tyres for a "gravel" bike

Putting some information in this thread, for future browsers. I have just taken delivery of one of these, and am thus far happy with it. Now, to the information: The controller comes from Hangzhou VeloFox Intelligent Technology Co,. Ltd. It's the DM03 model. The manual can be found on the internet from searching, I used ebike controller with "advset" as a required term which got me there. In google put it in quotes to require it in the results. Holding the button on the left of the unit for a second or two soon after startup accesses the menu. You want to get to "AdvSet". The password for the metroneer ebike controller is 1657 Note when you search on the internet it's in the images of unit in the manuals! Passwords of 2480, 1486, and 3632 are around, but 1657 worked for this bike. In AdvSet you can change many things, including the top speed.

I know you've all been waiting with bated breath for my updates. Found (and fixed) the issue. It might have been obvious to some, but it was a bit insidious. The positive wire inside the battery pack had a poor connection, that had started to blacken, to the output port. There was still connectivity, so there was still 42V at the output ports, but there was about 50 Ohms resistance just through that wire. I've snipped off the end, re-tinned it, dug through about 6 miles of glue to get to the pin, and re-soldered it and it has good continuity. All fixed! Thanks for taking the time to read and reply, and help walk me through.

New rabbit hole. Why don't I simply bypass the battery BMS? It's on the (-) line, (+) goes right out to the port. Jumpering from the (-) port to the (-) battery simply bypasses the BMS. I won't benefit from the balancing the BMS presumably does, but for a 10 second test...

Updates: Tested each of the 10 cell packs inside the battery. 8 test at 4.17V, 2 test at 4.16V. The pack hasn't been charged since Friday night (it's Tuesday), so I don't think any pack is failing. Running the e-bike using the charger instead of the battery pack (up on a bike stand with the wheel in the air so there's no real torque and therefore current draw needed) works just fine. Works exactly as expected. I think this leads me to the little BMS board inside the battery pack. It has 4 N-mode mosfets on it, and I've located the data sheet for them ( CRSS052N08N ). Testing the source to drain in diode mode shows them all as shorts. Visually they seem fine. I think they test as shorts in circuit is because there's a resistor in circuit between them, so I'd have to take them out of circuit to test. I can do that next, assuming people agree I'm chasing down the correct rabbit hole...

Great, thanks, will try that today and report back.

The only part I didn't follow was the "voltages at the discharge". Do you mean at the battery output terminals (not the charging port)? If so, yes, exactly and only there. Or did you mean voltages while trying to pull some power from the battery? Testing each cell group is next up. I tested the battery first, got 42.1v at the output ports normally going straight to the controller, and then went down, "well if the battery outputs 42V, what is next down the line that could be bad?" route.

Hello, I've happily put on about 5000 miles over 5 years on a yosepower KT-based rear wheel system. I've had one or two breakdowns in that time, but now I am having a time diagnosing/fixing this latest one. (Still very happy with the system) It's a KT controller attached to a bottle-style 36V battery, with KT-LCD3 display. On Friday, bike gave a judder and quit, electrics off. Holding the power button makes the display light up for almost a second, before it shuts off. Thinking this was some type of short-circuit protection kicking in, I went into diagnosing mode, disconnecting, isolating, simplifying. In all the tests in the next paragraph, everything else is disconnected, including motor, but also PAS, brakes, etc. I've tried with each of them connected, and the behaviour doesn't change, so assume they're all unconnected in the below. I replaced the cable between the battery and controller. Same behaviour. I replaced the KT-LCD3 with a KT-LCD4. Same behaviour. I replaced the actual controller with a KT-compatible no-name one off amazon. Same behaviour! All permutations between new and old parts have been tested as well. The LCD display can light up momentarily, almost every time. The only thing left un-replaced is the actual battery pack. This battery pack fits is the bottle-style type, where the controller is in the mount. In the replaced-controller tests, I directly and correctly attach the new controller to the +/- of the battery pack. I faked the battery by using the battery charger hooked up to the controller (42V/2A), with the controller and LCD display only. Obviously I can't/shouldn't hook up the motor as the current draw would be too much for the charger. This happily powers the LCD controller and I can press buttons on it, change settings, keep it alive for as long as I want. The battery pack was partly depleted on Friday due to riding around. I of course charged it overnight. It charged up, the charger LED was green in the morning, from being red (charging) before. The little 5-led display on the battery agrees it is fully charged. A voltmeter on the +/- of the battery itself gives 42.1V, which should be perfectly fully for a 36V battery. I was originally blaming the controller, since many posts on here talk of leakage current through the controller mosfets giving enough power to almost power the display, even though the battery itself can't give much actual power when turned on, but I replaced the whole controller with a different one. How do I best test the battery? Have tools including a good fluke multimeter. The blade fuse in the battery was good. I can test the cells inside for equal voltage. Can the BMS inside the battery be at fault here? Can I just wire the battery pack to some incandescent bulbs in series (to drop the current to e.g. 5-10A) as a load test, or will that freak out the internal battery circuitry? Thanks for reading this long post! I can add more details/tests if helpful!