Electric bikes – summer must be here!

Because, once again, my bike is off the road! Early this week I had the following problems all in the same day – a puncture, a broken spoke nipple causing the whole wheel to go out of alignment, another melted connector between the controller and the motor, and the same random cut outs at the top of the hill on the way home. 13 gauge spoke nipples are slightly rarer than hens teeth in NZ, so I have ordered a supply from my chinese supplier, but I may have found a local supplier and may be able to get the bike back on the road by the weekend! I think the random cutouts may be down to the 45 amp Anderson connectors not being up to the job. I have melted two now on the controller/motor connections, so there is no reason to believe they will be any better on the battery/controller connections. I’ll just have to find something better (and probably more expensive) or resort to soldering and screw connectors.

Posted in Electric Bikes
4 comments on “Electric bikes – summer must be here!
  1. Dave says:

    Hi Phil,

    There seems to be two possible problems with the Andersons. I am not using a dedicated tool, as the connectors are pretty simple. However, putting enough force into my Jaycar crimper is quite difficult, so I may not be getting enough compression on them. However, if I do get them compressed enough, there is always some straightening to do to get them into the plastic parts! The second issue seems to be at the point of contact, which is actually very small. Even when the Andersons were working fine, the three motor controller connectors would be running very hot, and eventually the plastic housings melted around the connection point.
    So given that I am pretty useless at putting Anderson connectors together, and the doubts I am having about the source of the connectors (buying in bulk from Australia – may be cheap chinese copies), I feel the XT60s have been the perfect solution so far, they are tricky to solder well, but when it is done properly, the coonection is massive and strong. The amount of contact in the three bullet connectors is quite large, and the bullets are very high quality materials.
    Soldering the andersons was something I was going to try, but 50 amp cable is a heck of a heat sink, I was worried about getting the good connection on the lightweight anderson connector! Good luck if you go with it and let us know how it goes.

  2. Phil says:

    In my battery pack I am only using the BMS for balance charging. Having a separate charge connector to the battery and the discharge connector (bullets) to the motor controller. As you say on a 300 watt motor/controller 18 amps should be the absolute max 18 amps x 36 volts = 648 watts but I think this is typical for a nominal 300 watt continuous motor. So, a 45 amp Anderson Powerpole should have not trouble with your connection. I should add the caveat that I am an a accountant but avid Endless Sphere ebike reader! I have a Bafang BBSHD – 1000 watt motor coming (possibly not strictly kosher) but the controller on this is 30 amp – and Andersons seem to be highly recommended. I had a Bafang BBS02 500 watt (limited to 18 amps) motor – the bullets were fine on this. I think the high current draw must be due to some short somewhere in the controller or motor. Your range would be a major snag and other components must be getting HOT!
    Enjoying your blog 🙂

  3. Dave says:

    The random cutouts may be down to the low current connections between the battery cells and the BMS. I have half suspected this before, but as part of testing the cells, I have put my 6 cell voltmeter in line with each set of 6 cells at a time. When plugged into the first set, the cutouts still happened, but the 6 voltages all stayed normal. This was good, as it was one of these cells I suspected. So I plugged it into the second set. This involves splitting the connection between the battery and the cells, and putting a short set of cables with the same male and female plugs, into which are spliced the voltmeter connections. Since then, the bike has not cut out. Time for some new low current BMS connectors, maybe some 9 pin D connectors as used for computer connections. The automotive connections may not be doing the job.

  4. Dave says:

    Found the 13g spoke nipples and fitted one, repaired the puncture, but the tyre is pretty worn, so have ordered another tyre and a couple of inner tubes. That just leaves the cutting out problem. Time to start looking at issues such as overheating, high resistance and flaky cells in the battery! When the final parts come for my 16 cell recording voltmeter, I can start tracking bike and battery conditions as I ride!

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