Battery and VESC in Detachable Box - Thief Safe


I want to build a city e-bike with a detachable hard case that contains a 100/250 VESC and a battery. I plan to take this case with me when I lock and leave the bike.

I haven’t found much information on using the controller in this way. Could this work?

For the connectors, I am considering a 3D-printed solution using three bullet plugs for the phase wires and a D-sub or HDMI connector for all other connections.

The top of the case will be made from a heatsink, to which the VESC and the BMS will be attached.

I read that I can do without an anti-spark switch by bridging the anti-spark XT90 or QS8 connectors, which I will use only the first time I connect the battery and if I don’t ride the bike for more than 1-2 weeks.

For daily use, I plan to rely on the on/off function of the VESC. If I understand correctly, the VESC will be on if I bridge the turn-on pins and will turn off if I disconnect them. This way, I can put a switch on the handlebar, but the controller will also turn off if I unplug the DIY connector coming from the battery/VESC case, as this will open the loop.

I don’t have any experience with VESC, so I am concerned that there might be something I don’t know which could cause problems. For example, a loose connection could happen sooner or later, which might be dangerous if it occurs while riding or could damage the VESC.

Also, what would happen if I accidentally turn on the controller while it is detached? I would greatly appreciate hearing your thoughts and recommendations.

If the vesc you choose even has those. Not a given on every model.

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I’m considering a 20s build, so I’ve been looking into the Tronic 250r or Trampa 100/250. I’m also open to other suggestions and also suggestions for BMS. Maybe the Nexus 20s BMS?

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I’d recommend checking aliexpress for some high current waterproof connectors, and running a separate waterproof connector. I like the Weipu SA series but I’m not sure if they offer one with high enough current rating for your use. I don’t see an issue with unplugging/replugging in the esc wires as long as they plug in the same way, but it may fuck with the resistance and phase readings. I’m no expert in vesc so I’m not sure what kind of impact it would have. I think it’s ok to just run bullets but it is best to have some sort of waterproofing in case of splashes and rains. Also, quick disconnect connectors are just sexy lol.

In terms of BMS I usually go for DALY but there are plenty of smart 20s bluetooth compatible bmss in Aliexpress or other.

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Sounds like a fun project. Here are my thoughts:

  • I think your connector plan sounds OK. You might also consider this connector which has gained popularity in the DIY onewheel scene. SuperFlux Female connector – fungineers
  • Inside your case, I would make a physical separation between the vesc and the batteries. I have seen phase wires fail and I wouldn’t want that heat near the battery.
  • I would add a button to the case for on off. IP67, latching for anything without vesc express, otherwise momentary. VESC express supports auto off.
  • Loose connections cause high resistance which can cause wires and connectors to fail. Everything in a mobile build has to be very secure.
  • No issues if you turn it on while disconnected as far as I know. It will probably fault but will clear once connected.
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Just use a QS8S or XT90S loopkey for turning it on or off.

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You might want to reach out to @AmericanFietser on twitter for how he secures his ebike in urban settings even when there is bike rack to use. from what I’ve seen he has had no issues just using a rear wheel lock on his e cargo bike but idk what the heck that is tbh

edit I meant to say when there is NO bike rack :person_facepalming:

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