I finally made some progress on the drive-side box. I mounted the VESCs on standoffs. The nuts on the motor side of the VESC were scary close to the phase wires, so I put some heat shrink over them. (Those M2.5 nuts are damn tiny !) Same thing for the PPM pins. I had to shorten the battery wires on each VESC in order to tame the spaghetti monster somewhat.
Tomorrow I’ll tackle the mechanical side and mount the motors on the board and maybe hook everything up for a bench test.
Your battery wires are going to end up being pretty long with the spegetti and the wire connecting your 2 boxes. The vesc come with 3 beefy capacitors to deal with this however your wires are so long I think youre pushing the limit. You should probably shorten your spegetti monster a bit to cope with this. Good luck with the rest of your build.
Finally found the time to put the drivetrain together. Belt alignment seems to be acceptable, will have to see how it goes once I can spin the wheels with the motors. These Enertion R-SPEC motors are a thing of beauty.
Note to self: don’t forget threadlocker on all bolts before first ride 
I also managed to hook up the Nunchuck RX to a longer set of wires so I can put it on the other side of the box. I put the RX back into its little case to give it some protection. I’ll probably hot-glue or double-side-tape the RX into the box somewhere.
I powered up the VESCs for the first time today. Updated the firmware using the 2.5 BLDC tool for OSX without a problem. Configured them as master/slave. I tested the Nunchuck connection to the master VESC, all seems to be OK.
Is there any way to ‘listen in’ to the CANbus communication to see if the VESCs are talking without having to power up the motors ?
In the next few days all will be coming together.
I just took a second look at the BLDC tool and managed to answer my own question: In the realtime data tab you can listenin to the CAN data coming from a slave by clicking CAN Fwd and entering the slave ID:
I got realtime data from my slave VESC so all is looking good for a bench test under real power soon.Another note to self: set input voltage shutoff to correct value before test ride.
Hi, could you post pictures of both your ESCs connection? pretty please 
and your power supply wiring.
Hi @NIK, I don’t have access to my board at the moment but if you scroll up you’ll find a picture of the drive-side box containing the VESCs.
The battery leads come into bullet connectors, from which I run a wire to each VESC so thats 2 wires per bullet connector, soldered on.
The CANbus connection is just a set of connecting wires between the two middle pins on the 4-pin connectors.
I’m not sure this answers your question, feel free to ask.
I’ll post a picture of the finished box later today after I’ve finished my post-christmas chores
That is super clear wiring pictures. Thanks, dude and merry Christmas
I didn’t let having only one VESC VESC stop me from doing my first test ride today. I left the unused motor on the board but removed the belt. I was quite surprised to find only one motor was sufficient to drag my 90kg ass up some hills. I can’t wait to find out what 2 motors will do !
I added a tie-wrap around my battery box to make sure I wouldn’t spill my cells on the pavement on my first ride:
Weather was great for the time of year, and carving on the 90mm flywheels was buttery soft:
Some stats: Distance covered: 10.8km Average speed: 18.23kph Max speed: 39kph (I had the ERPM limited, this was downhill)
Peak current: 23.27 A Peak power: 1114.6W Battery charge used: 2139mAh
Start voltage: 49,87V End voltage: 46,11V
I’m not happy with the range of these Multistar 5200mAh batteries, it appears their capacity spec is inflated, I have only been able to draw rougly half the charge of what was specified. Towards the end of my ride I could clearly feel the batteries increasingly not being able to cope with the hills, which was a bit of a disappointment. I might go for a second set of Zippy Flightmax cells after all.
I was very pleased with the Nunchuck connection, no dropouts at all. Pretty impressive range too. At one point I had my youngest daughter riding the board with me on the stick and at about 10-12m distance I would typically lose the connection.
Excellent build. Im really looking forward to your dual motor stats.
A lot of people are surprised by single motor power but there’s this myth of dual motor being the only way floating around here.
We’ve never needed 2 motors to climb hills. I weigh 200lbs and haven’t had an issue with speed or hills from day one. 63mm motors, 150a car escs @ 6s and 15mm belts has always worked well. The dual motor hype started with boosted. Twin 63’s @ 12s is overkill.
Second test ride today. This time on flat ground (23m climb) and pretty steady speed using the cruise control
Distance: 9.36km Avg speed: 18.3kph Peak power: 1035W Peak current: 22,5A Charge used: 2019mAh End voltage: 45,9V
Max speed on this run was 30,5kph, which corresponds nicely to the theoretical speed I calculated using a max ERPM of 30000 (which corresponds to approx. 4286 mechanical rpm on a 14pole motor) I had set in the VESC to protect me from myself
The batteries suck, they should be giving me double this range. It was only 12°C but I don’t think it’s the temperature. I think I got what I paid for.
No nunchuck dropouts.
I did manage to trip the VESC hard (ie not soft) twice, each time it happened when I tried to overtake a cyclist and accelerated hard. I have no idea why this happened. Any ideas ?
Hi trbt555,
It looks like you are using 12S, so shouldn’t you be able to safety run on voltages from 50.4 to 38.4 (assuming starting at 4.2V per cell and ending at 3.2V per cell)? It looks to me that you should have quite a bit of capacity left if your end voltage is 45.9V.
I experienced similar behavior with my now dead VESCs. I pushed them hard, they cutout, and never came back. Ended up faulting the DRV chip on one and a temp sensor on another. I am not sure if this is an issue with that batch of VESCs or what. I have one coming from @chaka with heat sinks that I will try out next.
OMG @Jeff you’re right I don’t know how I came up with 3,7V per cell !? Thanks for the wake-up call. I had somehow set my cutoff voltage and hadn’t given it any further thought. Apparently I’ve been leaving half the capacity in the battery.
I retract my earlier statements regarding the Multistars pending further testing.
On the issue of tripping the VESC: I’ll see if I can log someting on my next ride but it does seem similar to what I saw on my bad VESC: push the stick and the VESC just shuts down and reboots.
You were most likely tripping the low voltage cuttoff if you had it set at 44.4v. The voltage will sag under high current use. One way to combat voltage sag is by adding more capacity.
Yep, probably the Multistars not being able to cope. Am I correct that I could counteract this by limiting the battery current in the VESC ?
Yes, adjusting your max current settings will help. You may not need to once you adjust your low voltage cutoff.
@trbt555 Thanks for these updates; I appreciate the testing and the feedback. When you say that you tripped your VESC what did that feel like? What was the result? I’m thinking back to a few times I thought that I lost controller signal with a nunchunk, and I think that they were all during hard acceleration and before I fully configured VESC for my setup. If you were accelerating hard and the VESC reboots, did you get tossed?
I think @chaka could be right, because my low voltage cutoff was set so high, I was probably tripping it by demanding too much from the batteries. I don’t think it was the nunchuck.
What did it feel like ? I hit the stick to overtake a cyclist and all of a sudden I’m no longer on the board but running. It just cut off all power.
I’m actually very happy with how the nunchuck/VESC control feels. Very precise, braking is just right. @onloop made it very easy by putting default r-spec settings in the VESC.
On the mechanical side, My board seems to have a few rattles that are bothering me, I’ll need to straighten those out too. I’ve owned Flywheels before, but these ones tend to “creak” like a new shoe when rolling. I hope this is only part of the run-in process.
