Black Sabbath: Teleport Prime, Weldless Battery

[drdrs]

This bike (black and built while on sabbatical) is a typical hub motor with enduro frame build.

The unique aspects are:

- Teleport Prime 90 frame
- Custom weldless battery design (14s5p VTC6, 80 mOhm IR)
- ENNOID SS BMS
- CircuitPython-based dashboard display



Most of the parts were taken from a previous build (https://endless-sphere.com/forums/viewtopic.php?f=6&t=101184) and moved to the teleport frame.



The battery uses connector bars from Vruzend packs along with laser cut acrylic to hold the contacts and cells in place and provide mounting points.



The display is based on the Grand Central board from Adafruit and uses CircuitPython for the code. The repository is located here: https://github.com/dsoto/ASI-ENNOID-dashboard

 

[fechter]

Nice. What forks are those?

It will be interesting to see how the battery holds up long term. It looks like you have thru bolts between each cell? At least it will be possible to repair if a cell goes bad. I would predict contact failures before cell failures, but I don't have much long term experience with a setup like that.

 

[drdrs]

The fork is the garden variety DNM USD-8 with the badging removed.

I rode a Vruzend for a year without any noticeable contact degradation. That battery was the 2.0 contacts and didn't have the barrel bolts so I did external compression plates. I had contact issues before I got sufficient compression on the plates. The weldless design adds bulk and weight and contact resistance, but the ability to easily rebuild outweighs that disadvantage for me.

Correct, I went fairly maximal on through bolts. To keep watch for connection issues, I display max and min cell row voltages on my display during riding and charging. In the past, cell connection issues presented as a row that charges or discharges more quickly than the neighbors since it has N-1 cells in contact. If I go out of balance that will be the first thing to check.

My measurements suggest that I'm getting about 3 mOhms contact resistance per cell with polished bolt heads compared to 0.5 mOhms published values for spotwelding. Was about the same for the Vruzend packs I've done. So, about a 10% penalty on a 30 mOhm cell. There may be some more gains possible with increased surface treatments.

Hope to see you again at the next Lost Sierra festival.

 

[fechter]

That's a good point; with cell level voltage measurements you should be able to spot a connection going bad.