Confirm Wiring Diagram

(Originally posted in the .builders site) So, I’ve read a ton of similar posts of people asking to confirm their wiring. And from all those, I think I’ve figured out how to wire my setup, but I’d like to pass it by all of you just to confirm that I won’t fry my components or light my house on fire.

My battery is a 12s2p Li-Ion from MBoards, which has a built-in BMS and a charge port (not pictured), and I’m pretty sure the battery meter I bought has a little switch on it itself, but if not, I can always add a momentary switch if I find that it’s an issue.

I’m not too sure about whether I need a fuse or not, I’ve seen people post both ways. If I should add a fuse, what Amp rating should it be? If both motors have a peak current of 45A, should the fuse be rated for 90+ A?

Also, there’s an XT60 connector between the battery and fuse, I just forgot to draw it. I’ve seen setups with many more connectors between the VESC and the rest of the wiring (left). Is it necessary or just a convenience?

Full Parts List

Any feedback would be appreciated! Thank you!

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Personally i like the xt90s as the removable key on a loopkey. Just easier to mount the xt90 on the enclosure cleanly.

Also i think if you have your battery gauge between loopkey and esc you won’t be able to monitor battery level while charging unless loopkey is in.

Yeah but he could just pop the key in to check charge level. Better than leaving the meter running constantly.

I.e. Meter turns on when board is on

Every battery ive had thus far has the metr wires coming directly from the battery.

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Same here. They’ve also all had an auto time out on the screen and a button to wake it up.

There are 2 main commonly talked about fuse locations:

  1. fuse between esc and battery.
  2. fuse between the board’s charge port and battery.

Fuse 1 is to protect your speed controller from pulling too much power (whether or not the controller can actually handle it) from the battery in a tough situation (steep incline from low speed). Some people here, myself included, prefer to run unfused because I know that the speed controller can handle a higher amp spike for a few seconds and don’t want the fuse to blow and throw me on my face. Others really want the protection of blowing a fuse, not a controller.

Fuse 2 is a requirement. If protects your battery from something bad happening with the charger or charge port. If the charger starts freaking out for whatever reason and doesn’t stop sending current to your batteries, it will start a fire. The fuse in this case will blow, saving your battery/house/family/life.

In each case the fuse should be rated dependent on the system. Fuse 1 rating depends on battery/bms setup and esc. Fuse 2 rating should be a bit higher than your chargers charging Amps.


I think @DerelictRobot fuses the charger rather than the charge port.

I know @b264 fuses charge port.

Sorry I have no idea why that copy pasted so much over

Thanks for the input! The battery I’m getting is from MBoards and it appears the charge port simply connects to the battery’s BMS (see 2nd and 4th picture). To follow through with the “Fuse 2” solution, I should just splice a fuse into the positive lead on the charge port wire? It looks like the charger outputs 1.5A so a 2A fuse should be fine, right?

As for Fuse 1, my speed controller can handle 150A instantaneous current per motor (300A total), and the motor specs state that its max current is 45A (I can’t find the motor curve but I’m assuming that 45A is the peak current when stalled), so the VESC should handle it.

The charger should be fused internally

Sometimes things happen where a fused charge port itself is desired, for example if no charger is present and there’s an issue.

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Stay away from mboards - do a quick search and you’ll see that they’re pretty unreliable and there batteries are not built well. If you pm me I can build you the same 12s2p battery but better, safer and cheaper!