[DRIVING] StreetScooter Repair and Reverse Engineering
Posted: Mon Mar 16, 2026 1:42 pm
Hey everyone,
it's been a while!
I recently took some time to work on the car, for procrastinatory reasons. Firstly, as I mentioned in an earlier post:
Dropping the pack (and especially raising it again later) sucked about as much as the first time. I also discovered that I had broken the vacuum-formed battery cover. So it isn't water-tight any more. Well, I hadn't planned on driving through water anyways.
After separating the pack halves (huge thank-you to my former self, being able to do that without dismantling the whole pack is a godsend). I took off the HVJB cover and, just to confirm my theory, measured continuity of the fuses, which actually existed! This left me puzzled. Logically, I checked for continuity between the fuses and the positive contactor and measured an open line, even though I could clearly see the cable! To be sure, I dug through the bundle, and followed the line. I measured again, and suddenly there was continuity! No matter how much I wiggled the cables, I couldn't get it to break again. I was doubting myself and the first continuity measurement at this point and I was really afraid that there might be a loose contact on that line, which I know to be dangerous.
The only way to remedy this that I could be sure would work was to completely disconnect the line that I suspected to be faulty and replace it with a new and completely separate one, which I did. While disconnecting the old line and connecting the new one, suddenly a crimp on the factory line came apart! This had been the issue all along! It now serves as a charm of luck dangling from the roof in the cab
After raising the battery again and verifying my success, I returned everything to factory state and now the inside of the engine bay looks as good as new.
With fresh motivation, I started fixing small issues. The driver-side electric window lifter motor hadn't been working since I got the car. From a forum post I had found earlier (but which I sadly can't find right now), I suspected the wiring in the door hinge. I took apart the door (which is easy, but you will have to destroy the vapor barrier, sadly). Of the 6 pins on the motor connector, only two are actually used. I didn't write down the model number of the motor properly, for which I'm sorry. But it's a common one that should be easy to find. The two pins are just positive and negative that can commutated to switch between raising and lowering the window. In my case, actually both cables were completely broken. It seems that the insulation on the window motor cables is much stiffer than the other cables, which contributes to them breaking earlier.
Another issue that had been driving me crazy is a stripped knurled nut on the bonnet. I fixed that with a 3D-printed part. It isn't perfect yet (I should have printed it with 100% infill) but it does the job for now.
Because I know that the BMS doesn't balance properly, I want to know the minimum / maximum cell voltages at all times. To not have to have a laptop with me in the car all the time, I set out to build an auxiliary display. I designed a 3D printed case for the LCD2004 module of my old 3D printer, added an ESP32, a voltage converter and a CAN transceiver. The software is very crude at the moment, but does work. It's written in Rust. I sadly can't share the source code publicly at the moment for legal reasons, but if you are interested, hit me up privately! The thing it's missing most is a CAN-based bootloader for the ESP32. Maybe a project for the future.
In other news, I had the weirdest malfunction just now. I had been charging the car over night at a public AC charger, as I often do. When I approached the car, I wasn't able to unlock it wirelessly, as I usually am. This might have been due to a low battery in the key, or some other issue. The wireless unlocking fails to work relatively often. So I unlocked the car manually, but to disconnect the charging plug, I had to use the manual override. When I first started the car, the dashboard showed me a fully charged battery and a range of 160km and my custom display showed min/max voltages of 4.035 and 4.110. Not great, not terrible. But also, the dash displayed the "electric drivetrain" error, that usually seems to come from the inverter or rather the DC/DC converter in the same module. It usually goes away by restarting the car, which I did. Afterwards, my range hat dropped to 0km and the SoC to 19% (about the value at which I started the charge cycle). Even worse, my custom display now had a minimum voltage of 0.000V on it! None of the contactors would close (Main, OBC, PTC Heater). Reconnecting the 12V supply didn't bring any change either. Nothing that I tried helped. I was already considering having my car towed to the only specialized workshop nearby, when I realized that the fault had to be within the BMS (because it reported an obviously wrong diagnostic voltage) and that I hadn't been able to unlock the car properly (even though it usually complains when I try starting it and it can't find the key).
So I started mashing the buttons on the key again and oh joy, oh glory, I was able to lock myself inside of the car! (Unlocking didn't work yet, but you can't have everything I guess). In any case, after that the BMS started to behave normally again and I was able to leave the time-limited parking space I was on. Unlocking also started working again.
Not today, vendor-specific (extortionist, overpriced, rude) workshop, not today!
As most immediately obvious problems are solved now, I have to mark this thread with DRIVING, I think. But that doesn't mean that I won't post updates here, since I won't stop repairing, modifying and improving the vehicle. One of the things I would very much like to do is, for example, to add an HV inverter. We will see! Have a nice week in any case, everybody!
it's been a while!
I recently took some time to work on the car, for procrastinatory reasons. Firstly, as I mentioned in an earlier post:
As it turns out, I was wrong again! My brother had convinced me to drop the pack again, since we had a Saturday with exceptionally good weather and to fix the fuses properly instead of building a custom Y-cable. I had already ordered them (from Voelkner, including shipping around 10€ a piece). By the way: should you need them, they are "EATON 20CT" fuses. If they are hard to get, contact me, I have 4 spares.
Dropping the pack (and especially raising it again later) sucked about as much as the first time. I also discovered that I had broken the vacuum-formed battery cover. So it isn't water-tight any more. Well, I hadn't planned on driving through water anyways.
After separating the pack halves (huge thank-you to my former self, being able to do that without dismantling the whole pack is a godsend). I took off the HVJB cover and, just to confirm my theory, measured continuity of the fuses, which actually existed! This left me puzzled. Logically, I checked for continuity between the fuses and the positive contactor and measured an open line, even though I could clearly see the cable! To be sure, I dug through the bundle, and followed the line. I measured again, and suddenly there was continuity! No matter how much I wiggled the cables, I couldn't get it to break again. I was doubting myself and the first continuity measurement at this point and I was really afraid that there might be a loose contact on that line, which I know to be dangerous.
The only way to remedy this that I could be sure would work was to completely disconnect the line that I suspected to be faulty and replace it with a new and completely separate one, which I did. While disconnecting the old line and connecting the new one, suddenly a crimp on the factory line came apart! This had been the issue all along! It now serves as a charm of luck dangling from the roof in the cab
With fresh motivation, I started fixing small issues. The driver-side electric window lifter motor hadn't been working since I got the car. From a forum post I had found earlier (but which I sadly can't find right now), I suspected the wiring in the door hinge. I took apart the door (which is easy, but you will have to destroy the vapor barrier, sadly). Of the 6 pins on the motor connector, only two are actually used. I didn't write down the model number of the motor properly, for which I'm sorry. But it's a common one that should be easy to find. The two pins are just positive and negative that can commutated to switch between raising and lowering the window. In my case, actually both cables were completely broken. It seems that the insulation on the window motor cables is much stiffer than the other cables, which contributes to them breaking earlier.
Another issue that had been driving me crazy is a stripped knurled nut on the bonnet. I fixed that with a 3D-printed part. It isn't perfect yet (I should have printed it with 100% infill) but it does the job for now.
So I started mashing the buttons on the key again and oh joy, oh glory, I was able to lock myself inside of the car! (Unlocking didn't work yet, but you can't have everything I guess). In any case, after that the BMS started to behave normally again and I was able to leave the time-limited parking space I was on. Unlocking also started working again.
Not today, vendor-specific (extortionist, overpriced, rude) workshop, not today!
As most immediately obvious problems are solved now, I have to mark this thread with DRIVING, I think. But that doesn't mean that I won't post updates here, since I won't stop repairing, modifying and improving the vehicle. One of the things I would very much like to do is, for example, to add an HV inverter. We will see! Have a nice week in any case, everybody!