RobinC

I am assuming that these wires only carry a few mA so I plan to use some thin 6 way multicore cable - e.g. Maplin part no XR26D. I haven't decided about the connectors for this cable yet. Robin

The Tongxin 3 wire controller senses the voltages on the motor wires to determine the current position to control the timing. Perhaps a dodgy connection could confuse the controller and cause some sort of misfire.

Are you using the original Tongxin connectors Frank? Some have blamed connector problems for controller failure. I think Cytronex uses stock Tongxin controllers & motors but use high quality connectors, so if they are proving to be reliable the anecdotal evidence supports this theory. Robin

I have a similar project under construction at the moment so am facing similar issues. My Ping charger came with a socket supplied. Have you checked it isn't somewhere in the box? This round 3 pin mains connector used to be commonly available but it is years since I bought one. Are you using a 24V or 36V Tongxin? Which connector are you using for the motor? I am thinking of using Canon Sureseal connectors which are waterproof & available in 3 pin but I officially I should use some specialised & expensive tooling for crimping etc. If I can't get by with basic tools I will have to think again. I have seen speaker connectors used on some bikes. There are some connectors rated for tens of amps, but I guess not usually waterproof. For more obscure bits I would try Farnell or Radio Spares first. Robin

I guess this was for one of their V1.0 ebay batteries? My V2.5 36V 10Ah which I ordered from their website arrived last week which also got through customs without charge. Total cost including postage was £259 but it will depend on the exchange rate at time of order. It took 10 working days to build plus 5 days for shipping. Dimensions are as stated on website but weight is closer to 3.8Kg than the 3.7 claimed. It will be a while before it gets tested as bike is still a work in progress. Robin

My Mums Nexus-8 bike has one of these on the back. The braking response can be a bit non-linear but for a back brake on a utility bike I think they are OK. Some of the smaller roller brakes further down the Shimano scale are even weedier. Shimano is bringing out an improved version: Search for BR-IM80 Robin

Did anything turn up? I'd also be interested to read this.

OK thanks, that is reassuring. Some of the other failures I read about could possibly be explained by overheating or some other excuse but in this case I couldn't see any good reason. Has anyone experienced controller failures after zooming downhill? Someone on endless-sphere claimed: "...One note on the [Tongxin] controllers, they are vulunerable to high levels of back EMF. If you go down a steep hill, the voltage generated by the motor will burn up the mosfets, I suspect because the internal diodes are conducting. The work around is to add some protection diodes on the three motor leads, to GND and Batt+." An extra 6 diodes shouldn't add much cost so maybe Tongxin already do this on more recent controllers.

Did you figure out what might have caused the controller to die? A bit worrying if they can keel over for no good reason, I'm think of doing a Tongxin project soon. Robin (1st post)