LaCroix Prototipo Rebuild | A Custom DIY Restored
Prologue
I have never posted a build thread before, and I figure that this is a good place to start. This is the first of a few to come, and in each one I’ll try to detail some of the story of the build, since there are often amusing bits here and there that add to the human element that surrounds the construction of an expensive toy.
This build isn’t an entire build, but more of a recovery. A recovery that I was so glad to be involved in, as it saved a very pretty LaCroix Prototipo from the bowels of incompetence.
Chapter 1: An Unfortunate Beginning
When the person who bought this board got it, it wasn’t working too well. It barely ran at all, wouldn’t charge normally, and the Neptune BMS was reporting some less-than-ideal numbers. Essentially, one P group was dead, and the rest were out of balance. The person was kind enough to trust me with poking around the board, and this was the first time we had met. He brought it over, I poked around with my meter, and found something that I thought was very cool.
Chapter 2: Unforeseen Circumstances
The dead P group had negative voltage.
I had read about cells having their polarity reversed from overdischarge, the shifting of ions from one side of the separator to the other and then the internal chemical unicorns rebuild their homes on the cathode and tank the real estate value of the annode. All very cool scientific-y stuff. However, I had never seen it in person, and I started smiling. The owner of the board noticed my joy and was relieved to see no worry. I then of course explained that this is actually a bad sign for the battery, but I had never seen that in person before and it was just really cool.
Oh, and also, here’s what she looked like inside:
Yes, that’s a folded nickel series connection with only 3 pieces of 0.15x8mm strips. Yes they popped right off when I went to lift the groups out.
More nickel popped off when I went to remove the pack, so that was fun. This was all after we had agreed that I’d build a new battery for it, since replacing the dead P group would technically fix the board, but it wouldn’t be a safe battery, and the new P group would be at the mercy of the rest of the battery, and it would be a tanking of however much that group would cost to make and install.
I also stressed that I wasn’t comfortable leaving that battery as is, and I couldn’t guarantee the condition of the whole pack after the group was replaced.
We then came to the agreement that I’d just go to town on it and give it back to him working. Which was a nice thing to hear.
Chapter 3: She’s Had Work Done
I removed almost everything from the enclosure, including the Neptune BMS. I’m not sure why one would use a Neptune for this…it seems like overkill and an unnecessary burden to set up and use. It’s a really nice BMS, but I didn’t personally think it was appropriate for this board. Either way, out it came after a very frustrating fight with glue and VHB. And also carefully removing all the balance leads from the battery and unbundling the wires. Blech.
The old pack really was a mess. It gave me tons of ageda taking it apart, especially since nickel was just falling off from weak welds. Nickel was double stacked, and soldered on to over the cells. There wasn’t much insulation, and there were bare cell wraps in contact with the corner of the BMS and pinching some wires.
I disassembled it into the constituent groups, wrapped them all up and boxed it for the owner to return. The Neptune BMS as well was set aside, and I recommended he sell it to help recoup some of the costs.
The new pack was also going to be made from Samsung 40T cells, because it seemed poetic and they were available from a reputable source. I had originally slotted some P42a cells, but this was before the recent batch came in and there was some drama of old rewraps and/or fakes from a vendor. If you were around the battery builder’s club a few months ago, you likely saw that whole thing. All the cool kids were there, it was a good time.
Anyway, the usual planning stage happened.
I checked all the cells for both voltage and IR, just to see if there were any obvious outliers.
Then the construction of the battery began.
In the following shots, I assure you that I did not weld in the center of the negative poles. The angles and framing betray the reality.
The PVC shrink wasn’t working like I wanted it to, and instead I wrapped the segments in an overlay of kapton tape, and then finished with Tesa tape on the ends. It’s under the Tesa that I used foam tape to secure it within the enclosure. It’s secure, yet not very difficult to remove if needed.
Daly 12s BMS fit more cleanly than the Neptune, and has always been reliable for most general purpose use. The balance connector is also conveniently placed so that group voltages can be checked without too much fuss. It looks cramped, but the connector has enough room to be removed and lifted upward to accomodate a check with a multimeter.
Chapter 4: Some New Kicks
Unfortunately I didn’t take very many photos of the last days of the build. However what I did change apart from the internals were the motors. What came on there were a pair of Maytech 6396 140kv motors. Now, I don’t personally have the greatest regard for Maytechs. Specifically because of that ridiculous thing they do where they just extend the motor windings out of the can and use that as the phase wirings. It’s clunky, makes it nigh impossible to cleanly change wire lengths due to the enamel coated wires, and also makes the phase wires stiff.
What ended up going on the board were a pair of Flipsky 6384 motors, 190kv. Originally, the top speed of the board was about 24-25mph. And after the build was done I got it up to 31mph.
Before all was said and done, the deck needed some inserts re-adhered into the holes.
And a Bamboo Puck was added as well.
Chapter 5: A New Lease On Life
This brings us to the end… She was put back together, set up, and then taken out to a very long smooth bike path that runs along the coast of the island (Long Island, NY).
She ran like a dream, carved like butter, and punched like a toddler who’s just been denied a Happy Meal.
I do have a video coming up with footage of the build, and some nice drone footage of the test ride.
She went about 22 miles and still had about 10% left in the tank. That bottom of the charge usually isn’t proportional, I know. But still, that isn’t bad for punching it at 25-30mph with a 190lb rider.
