[FIRST DRIVE] StreetScooter Repair and Reverse Engineering

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Heye
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[FIRST DRIVE] StreetScooter Repair and Reverse Engineering

Post by Heye »

Hey folks,

my name is Heye and this is my current (and also first) EV project. It's not a conversion, but I think it fit's the OpenInverter spirit best since there doesn't seem to be a StreetScooter specific community and I want to learn automotive reverse engineering with this project. In this thread, I want to document my efforts and maybe even enable other people to repair their own absolutely underdocumented StreetScooter.

About me: I'm a German computer science student with a long-time interest in electronics and have been participating in the climate movement for some years. But I also like cars/trucks (and fixing them myself), so buying a broken EV and trying to fix it is basically the perfect project for me.

So what even is a StreetScooter and why did I want one? Briefly summarized: The German postal service wanted a new fleet of EVs at a time where there weren't many utility EVs around. So they bought a startup from a professor at a prestigious German technical university (not mine, sadly), trying to develop just that. The company had its ups and downs (mostly downs) and recently the postal service sold the company (tough it keeps a fleet of a few tens of thousands of their vehicles) again, after which it soon had to declare bankruptcy (StreetScooter, not the Germany postal service). Somewhat recent news said that StreetScooter are trying to move production to Thailand, but it is unclear whether that is actually happening. StreetScooters never sold well outside of the Postal service due to their high sticker price of 40.000€.
Since the StreetScooter became publicly known, I always wanted one. I like utilitarian vehicles, the StreetScooter is made for cities (and I live in a pretty cramped one) and they can be had pretty cheaply (because they don't have all that much in common with modern "nice" EVs). In short, the StreetScooter is the "Slate truck we have at home", which is funny because the Slate truck, which I also like, probably won't be sold in Germany if it even makes it to market.

After scouring the online platforms for some time, I found a StreetScooter in the Netherlands that I absolutely fell in love with on first sight. It had a truck bed (those are around 500€ separately), the largest available battery (40kWh, which is frankly barely adequate) and, best of all, it was listed for 3500€, which I managed to barter down to 2000€. It is one of the few trucks that wasn't used at the postal service and instead was sold to a third party, probably some Dutch municipality It even has nice orange lights on the roof. On the negative side, it was listed as "not charging anymore, drove until the battery was empty". But no risk, no fun, right?

So I lent my fathers bus, rented a trailed and took my brother and my best friend on a Roadtrippy car-buying adventure to the Netherlands.

Image

After getting the car home, I firstly had to charge the 12V battery, which was completely dead. Luckily, after a few days at 14.3V it was mostly fine again. So I tried starting it, only to see it shutting off again. It looked like it was tripping an electronic breaker or something like it. Later, I learned a bit of Dutch: "Sleutel niet gevonden" means "Key not found". The car has a keyless go system, which I wasn't used to. The other key had a working battery, so I was able to activate the 12V system properly. Starting the car wouldn't work, with it just saying "Garage" (meaning "Workshop"). Charging it wouldn't work either, as I was promised, but I got two different errors! The first one was the fault light at the EVSE. I learned that you can't just use a Generator to charge your EV, you actually have to ground it! But the second one was more insidious: The EVSE was showing that it was charging and the light at the charge port was blinking green - but at the wrong frequency! If it's blinking fast, there's an error, if it was blinking slowly, it would be charging fine. 12V charging was working though - you can see the LEDs at the 12V charger through the grill.

It was CAN Bus time! But first, since there was no OBD-II port (at least I didn't find it and I assume there doesn't have to be one, since there are no emissions to be monitored), I had to figure out how to open the hood, since there's no latch and I don't have a service manual. But it's easy! You open the doors and you remove the highest screws you can see. Then you can pull the hood in the direction of travel and then take it off. I didn't find any documentation on any component inside the vehicle or even any connector. But finding the CAN-Buses was easy. I took the connectors off at the inverter, the OBC and the VCU (that one is over the passenger footwell inside the passenger compartment) and looked for twisted pair connections. Measuring them with my multimeter, I wrote down those that had a resistance of either 60 or 120 Ohm between them (depending on whether the connected device terminates the bus) and choose the bus connecting the VCU and the charger for my first experiments. Not knowing the baud rate and other parameters, I guessed at 500.000 baud and 11 bit addresses. And Bingo! I now had so much data to work with in SavvyCAN! This was the point where my great saviours from this board came in. Thanks to a post from LRBen, and Jacobsmess who found it, I had a DBC file that fit my car almost perfectly! I don't think I could have done all the CAN reverse engineering myself at this point. Who knows, I might even have given up the project in frustration! Sadly, I can't contribute much back for now because I actually have a different (probably worse) charger.

After getting the car incredibly cheaply, this was my second incredible stroke of luck, since there is otherwise almost zero technical documentation on the vehicle. I am so very thankful!

Perusing the dumped data, it didn't take long for the problem to present itself to me: The BMS reports an undervoltage error! And yes, the voltages it shows are varying wildly - between 2.35 and 4.1 volts per cell. (Side note: Either the DBC file doesn't quite fit or something else is wrong, but I can only see voltages for 9 from 16 modules. All eight from the first string and only one from the other one).

I also learned that there are many different batteries for the StreetScooter. The one I have is "V6-16M". They are probably (I haven't opened it yet) organized in two strings of 8 modules of 13 prismatic Samsung cells each. So it's a 104S configuration. It is supposed to have battery modules from the BMW i3 inside, but that doesn't work out! All info I found online says that the i3 has 12S modules!

But I will be able to satisfy my (and maybe your) curiosity soon, because I will have to open the battery. I will charge the heavily discharged cells and try to find out what the secret CAN handshake between the battery and the car is, so I can work on both parts separately. I am a little worried about dendrites, but not too much, since I won't be driving the car at first. In the worst case, I will have to take one of the strings out, make the BMS accept it and live with the reduced capacity.

Opening the battery means dropping the battery first. That's easy enough with a lift, but I don't have one. And renting a trailer is expensive, so I had to make do with what I had - three shunting jacks, some wood and 6-Ton car stands. This was my procedure, which worked well:
  • Jack up the car and put it on the stands (doesn't need to be too high)
  • Remove the 12V battery and wait 10 minutes! The HV battery is not safe otherwise!
  • Remove the 2 nuts and 3 screws (10mm spanner) holding the protective plate in the middle at the front of the battery (it has a high voltage sign on it), then remove the plate
  • Disconnect the tool-less HV and auxiliary connectors, don't forget the grounding cable (10mm spanner). Especially don't forget it on reassembly!
  • Put tape over the receptacles and the plugs to avoid dust entering them.
  • Put two long wood bars under the battery as rails to drag it out sideways (you have the most clearance between the jacks there)
  • Support the battery with one jack in the front and two in the back (one in each corner)
  • Build three wooden cross stacks symmetrically to the points where the jacks are on the battery
  • Ensure that the jacks are still solidly supporting the battery, then loosen the screws (13mm hex head) fixing the battery to the frame. Don't put your head beneath the battery!
  • Slowly let the battery sink down using the jacks. Remove wood from the cross stacks as you do it.
  • When you are almost done, put round wood bars (like broom sticks) beneath the battery so you can roll it like the Egyptians did (dragging it was way harder than anticipated)
  • Roll it out and you are done!
How will I get it back in? No idea, that's a problem for future me.

Now closer-future me had a more immediate problem. Working on a battery is necessarily working on live voltage and you need protective equipment for that. To protect against electric shock and arc flash, should you stupidly drop and short something. Don't underestimate arc flash! I learned: That stuff is both heavy-duty and expensive.
And I'm a broke student. So what to do? I wasted a day asking local businesses for old equipment, which was a stupid idea. Broken protective equipments gets thrown away, not given away. You can't do it without thick 1000V rubber gloves, so I bought them from Amazon. Uvex brand, 50€. Too much for a one-time job, but oh well, it's my safety. I wouldn't trust anything worse. The face shield, which you also need, is stupidly expensive as well. My father has a different faceshield made from thicker polycarbonate, which I'm going to use. Alternatively, I would have used a motorcycle helmet, which should also provide at least some protection. Both solutions are not tested against arc flashes, but I'm quite confident here. For the rest of my body, I'm going to wear multiple layers of thick, pure cotton, work jackets and trousers, they are quite flame retardant and should also protect me well.

I will open the battery either tomorrow and the day after and post pictures then. Until then, isn't this just an amazing sight?

Image
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Re: StreetScooter Repair and Reverse Engineering

Post by Jacobsmess »

Glad the DBC files has helped. I have a contract with someone one who has a few working SS vehicles who provided the DBC so let me know and I can reach out to them if you need.
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Re: StreetScooter Repair and Reverse Engineering

Post by Heye »

Thanks! I’ll definitely reach out if I get stuck.
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Re: StreetScooter Repair and Reverse Engineering

Post by ianlighting »

Apparently we have some in the UK aswell used for milk deliveries. I only found this after googling streetscooter because I hadn’t heard of it before.

Good luck!

https://www.milkandmore.co.uk/news/electric-floats
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Re: StreetScooter Repair and Reverse Engineering

Post by muehlpower »

I have dismantled an older one and used the technology for a show vehicle. Many of the CAN messages are the same. It no longer looks like a Street Scooter. ;)
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Re: StreetScooter Repair and Reverse Engineering

Post by Heye »

Here cometh the promised update!

I opened up the pack today with appropriate gear and was greeted by a few surprises. First of all, I was completely wrong in my assumption about what type of modules I would find inside. The type V6-16M does not contain prismatic cells, but 18650 cells! There doesn't seem to be any relation to BMW, but the actual manufacturer of the battery modules (maybe not of the BMS, more on that later) has a similar name: "BMZ". Searching the web, there are mentions that StreetScooter had batteries produced by BMZ, so that checks out.

Image
The battery and its modules.

Working with these modules was not as easy as expected. They are nice and symmetrical, but stacked two layers high, which has some downsides. More on that later. Here is how I dismantled the battery, with some added optimizations (note that I did all of this with appropriate rubber gloves, thick protective clothing and an appropriate faceshield):
  • Remove the bolts that hold down the plastic battery cover and remove the cover. A rattle gun is really nice for this.
  • Label the modules on top and take a photograph so you can put them in the same order on reassembly. I don't know if the order actually matters, but I would assume so until proven otherwise.
  • Remove all of the visible long metal bolts holding the modules down. There is a lot of them.
  • From every balancing cable, remove one plug. I always removed the short side and left the long side in place. You need to push in the latch and don't yank on the cable! Image
  • Now, to split the first string into two parts with 200V each, remove the bridge cover opposite of the HV plugs (don't remove the HV box cover until later!)
    You will notice that you can only do this for the upper string, the lower bridge cover is blocked by the upper modules. In my opinion, this is a stupid and service-unfriendly design. Removing the covers is needlessly difficult. You need a tool for this that is strong enough to bend the hook, but is either non-conductive or well insulated. I used a ground down glas fibre reinforced plastic rod. The hooks are really fragile, I broke a few while removing them. I will see whether I can 3D print replacements. Again, not very service-friendly.
  • Remove the bolts holding the bridge down and then the bridge.
    Image
  • With the added safety, now remove the bridges one step closer to the HV plugs.
    Image
  • Now you can remove the first module (labeled 5 in the image above).
  • You will see that you can't remove the other module (labeled 4), because it is held down by module 3. But you can lift it up a bit to remove the cover of the middle bridge of the lower string. Split that string now, for added safety.
  • Remove all bridges from the top string
  • Open the cover of the HV box containing the contactors and the BMS coordinator (I sadly don't have a great picture of this as my phone battery died before I could take one)
  • Carefully remove the busbars connecting the upper string to the HV fuse and the ground contactor. You will see that you can't remove the lower busbars yet. Great design, striking again.
  • Replace the HV box cover, but don't screw down the bolts
  • Remove all modules from the top string
  • Label the lower string and remove all bridges
  • Remove the lower busbars, then you can also remove the modules of the lower string
With one of the modules at my workbench, I started dismantling it. I found out that you don't need to (and also shouldn't) remove the plastic bolts holding the top and bottom module covers. The threads strip extremely easily. Instead, you can access the BMS board by pressing in one of the plastic clips on the side:
Image

The BMS "slave" board itself is quite an interesting (cost optimized?) design. There are no components on the bottom side and I can't see any transistors, which I would usually expect. But there are some big resistors, so maybe the single chip does all the balancing itself?

Image

This is the text on the chip:

Code: Select all

AA1N14T2A
MC35771ATA1
CTAL1820D
I wasn't able to find a Datasheet for the chip. Volkswagen was mentioned in the search results, so that might be a clue.

That's it for now! At some point, I might post about the insides of the HV box, but for now I want to focus on charging and balancing the modules. Tomorrow, I will start designing a safe connector.
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Re: StreetScooter Repair and Reverse Engineering

Post by muehlpower »

my googling has led me to this link.https://tr.aliexpress.com/item/1005008459058700.html. The MC33771ata is sold there, the photo shows a MC35771ata. Further googling shows that it is a BMS chip from NXP. The datasheet at mouser https://www.mouser.de/datasheet/2/302/M ... 517286.pdf. I think the two are at least very similar.
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Re: StreetScooter Repair and Reverse Engineering

Post by Jacobsmess »

Dimensions and weights of the cells would be interesting for the wiki. Thanks
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Re: StreetScooter Repair and Reverse Engineering

Post by muehlpower »

This description states that the “33” only describes the destination market. The entire type designation is also explained there.
NXP.png
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Re: StreetScooter Repair and Reverse Engineering

Post by Heye »

That's great! Thanks for looking it up. Seems like I need to work on my Google-Fu. I have decided that I will not build electronics to interface with the BMS child modules, but I should still find out whether their ordering inside the pack matters. The datasheet says that connecting an external EEPROM is possible and there is an unmarked 5-pin chip on the board that might be an EEPROM. It also lists "Addressable on initialization" as a feature, so maybe the EEPROM does not store the position in the string and order really does not matter? That would be nice.

Jacobsmess, I took these measurements. Are they sufficient?

523mm (including the terminal protrusions) x 282mm (including the side
protrusions) x 76mm (excluding stacking protrusions).

The width between the case sides without the protrusions containing the bolt holes is 257mm.

On the bottom of the module, there are stacking protrusions that increase the
height by 6mm. The distance between the outside of the module case and the
center of the bolt holes is around 6.5mm on both sides.

I can't take very precise measurements right now, so all these numbers are +/-
1mm.

I don't have a scale with an appropriate rating, so I can't really measure the weight right now
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Re: StreetScooter Repair and Reverse Engineering

Post by Heye »

Current progress: I made a plug that connects to the side of the battery so I don't have to get 14 connections right 16 times but only once.
You can find the CAD files on Thingiverse: https://www.thingiverse.com/thing:7060814

An active balancer and a BMS should arrive this week and with those I should be able to get these modules charged. My most capable power supply can go up to 50V, so with around 3.84V per cell it should be enough to charge and balance them for now, even if I can't charge them up completely and do a perfect top balance.
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Re: [WIP] StreetScooter Repair and Reverse Engineering

Post by Heye »

Time for another update (and the next one probably won't come earlier than in about a month).

I'm currently charging and balancing the modules one after another. This works fine, but takes lots and lots of time (at least I don't have to actively do anything). I am using these components:
  • Two 140W Lenovo laptop PSUs in series. This works fine if you use a plugs without an earth connector (IEC 60320-1 C8) and modify the receptacle (IEC 60320-1 C5) inside the PSUs to accept them
  • Ruideng DPH5005 Buck-/Boost module. Usually, this is my lab bench power supply. Now it's being used as a charger at its maximum settings. It's limited to 5.1A, but that's fine. If the whole pack were to be charged with a current of 5.1A, it would consume around 3.8kW, which is the power a normal European circuit can provide. 50V is slightly below the theoretical module voltage of 54.6V, so I can only charge each cell to 3.85V.
  • No-name Amazon BMS. I rely on this to stop the charge if any cell reaches 4.2V so the balancer has time to pull it down again. I don't expect that to ever be the case though because I only charge each cell to 3.8V so there is a lot of wiggle room. I'm also monitoring the voltages myself.
  • Daly Smart Active Balancer. (1A, the one with the two UART ports. Daly doesn't seem to have real type numbers.) I bought this, because it is relatively cheap, balances much faster than the resistive balancers on most BMS and allows me to read out the voltages using Bluetooth. The Android app (you do need it for setting up the balancer) is utter crap. I have a hard time understanding how you can fail so hard at building a simple app. I didn't manage to get it to run on Lineage OS. The voltage readouts don't always seem quite right, but they move in unison so maybe an internal voltage reference is bad? Anyways, it does the job but buyer beware.
  • Raspberry Pi B+ with a Bluetooth dongle
The Pi is the fun part! Standing on the shoulders of giants, I cobbled together a proof of concept Prometheus exporter that reads the cell voltages over Bluetooth. It doesn't work very well, but work it does! Now I can monitor and graph the voltages without the crappy app. Here you can find it: https://github.com/hamadmad/python-daly ... xporter.py

This is one of the better modules beginning to charge (and you can see a finished module that took three whole days to balance).
latest.png
It's quite interesting to see that on some modules the 5th cell is low, while cell 1 and 13 are usually high. On the previous BMS child-boards, the area around the bleeding resistors showed brown discoloration, while the conformal coating on this board is completely clear. I think it's possible that this is not only due to unmatched cells but also due to bugs in the BMS software.

Finally, a question to you all: Can anybody recommend a better active balancer (or an alternative fully automated and remotely observable solution) that doesn't break the bank? Currently, this is my main bottleneck because I can charge a lot faster than I can balance. I would be fine with paying around 50€ for anything significantly better than what I currently have (and I know that's very little money, I would just like to know whether I missed any much better option).
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Re: [WIP] StreetScooter Repair and Reverse Engineering

Post by johu »

There's this https://openinverter.org/wiki/16-cell_BMS but it balances very slow. Merely meant to keep cells balanced not to balance a very uneven pack
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Re: [WIP] StreetScooter Repair and Reverse Engineering

Post by Proton »

This is what I used to balance one pack at the time. balances with 4Ah. It is very fast.

Same balancer I use on my battery for my solar system. I do not use a BMS but just this balancer and my solar inverter starts and stops the charge based on the pack voltage.

This is the latest 8amp version but the 4 Amp version is cheaper.

https://www.aliexpress.us/item/32568029 ... pt=glo2usa

I would have used this on my car because is very very reliable but you need 6 and they do not communicate together. Also it is bluetooth and no can messages. I have 2 running on 2 different batteries and they are solid as a rock.
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Re: [WIP] StreetScooter Repair and Reverse Engineering

Post by Heye »

Quick update:

I'm now charging module 14 out of 16, hoping to reassemble the battery some time next week. I'm quite occupied with my studies at the moment so I may have to delay that a little longer though. I'm quite certain now that either most modules have been opened before or not assembled very well. There were quite a few broken plastic clips that I'm quite sure I didn't break myself. No module of the upper string has had discoloration on the BMS child module so far, while all bottom ones did. Voltages were way, way worse on the bottom string. Interesting. Moulding quality of the module cases wasn't always great either.

I was able to read "SAMSUNG INR1865" on the cells through the plastic vents, but the rest of the model code is obstructed.

When reassembling, I will have to put both strings in parallel again. This could potentially be quite dangerous and I don't have much experience with it, so I have some questions:
  • Is it fine if I split the upper string into four modules each, connect the big busbars putting both strings in parallel, equalize resistively at the split point and then reconnect the busbar/bridge that I removed to split the string? This way, I should only ever see a few volts of difference max, not the whole pack voltage.
  • I was planning on using some 0.22R resistors with a 5W rating, with one in series per volt of difference. I obviously need to have a difference of far less than 1V, so do I have to decrease the resistance further by putting them in parallel once I get below 1V? How long should I leave the resistors connected? Is it more in the range of minutes or days?
  • What voltage difference is acceptable for reconnecting the bridge?
  • Do the resistors need to stay connected while connecting the bridge?
  • Is it fine to use cheap 1000V DC PV fuses for added protection? Or do I really need to get something better?
Finally: It seems that I have arrived at the point where I finally should get a clamp meter. Do you have recommendations for a model that:
  • Works well
  • Doesn't break the bank (I was planning on spending at most 50€)
  • Arrives within the next week (ideally not from Amazon, my account there is broken at the moment)
  • Ideally has Bluetooth or a serial connection for continuous monitoring
  • Has a True RMS function
I know that's quite a lot to ask so I will also be happy with any other remarks on clamp meters, be they positive or negative. I'm certain that I will learn something.
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Re: [WIP] StreetScooter Repair and Reverse Engineering

Post by marcexec »

Danke für die detaillierter Beschreibung - wäre schön, wenn Du das durchhalten könntest!
Awesome (first?) project and we're obviously the right place :)
I'd love to see some more pictures if possible and what you want to use the truck for?
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Re: [WIP] StreetScooter Repair and Reverse Engineering

Post by gb993 »

Heye, looks like you have done some good digging.

The Samsung prismatics you assumed you had I believe we're fitted on both earlier and later vans.

With the charge inlet port - they are susceptible to taking on water so be careful charging after any rain or washing.

When they short - they smoke the OBC and as yet I have not found a replacement.
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Re: [WIP] StreetScooter Repair and Reverse Engineering

Post by Heye »

Thanks! That's very interesting. It's a lot of fun to me to see all the variants out there and to observe the evolution and the experiments StreetScooter carried out. I will be careful with the OBC, although it's quite possible that mine is broken as well. After all, they told me that it wasn't charging until the battery ran out. This might be the next project after reinstalling the battery.

For now, I just want to give a quick update since it's been some time. Sadly, I didn't have much of it to work on my project.
I managed to reassemble the battery pack tough, so here is my report on that.

It took a few weeks to charge all the modules separately. Measuring their voltage, they only drifted very small amounts, which was good to see. I used soapy water and compressed air to clean the shell, in which some dust and tree debris had accumulated. This time, I didn't follow the complicated procedure of the disassembly process. I did wear the same PPE, but I modified the battery slightly to make reassembly safer.

This is the (slightly simplified) process as I recall having done it.
  • I placed all lower modules back on the aluminum tray and connected the busbars to the HV box. There is no real risk of an electrical short because the other sides of the modules are not connected.
  • Connect the BMS data leads between the cells first, this makes reinstalling the cable ties easier.
  • One by one, I reinstalled the flexible busbars connecting the modules to each other, leaving out the bridge at the end opposite of the HV box. This way, there are only two times 200V across the length of the battery and there is no risk of short circuits while working on the HV box. After installing each busbar, I protected it with its plastic cover.
  • Before placing it on the modules, I cut away the outside-facing side of the halfway bridge cover that was preventing me from splitting both strings in half during disassembly. This is the modification I mentioned earlier. I temporarily put duck tape over it to avoid any danger while continuing with the reassembly process. If I ever have to work on the battery again (which is likely), this will make everything a lot easier and safer.
    photo_2025-07-31_22-19-12.jpg
  • I then put the upper modules on the lower modules and followed essentially the same process. I added duck tape to keep the plastic covers with broken latches in place. The tape will likely degrade, but I don't think it's going to cause problems. Don't forget the BMS data leads before connecting the busbars.
  • After connecting the busbars between the upper string and the HV box (still not much danger of shorts, though be as careful as if there was), I connected the BMS data lines (don't forget them!) and closed up the HV box.
  • Before connecting the busbar completing the lower string, I was surprised to measure around 300V between the terminals. Some highly resisitive load inside the HV box seems to draw some quiescent current. I verified that no measurable current was flowing when connecting the terminals over a 10k resistor. Additionally, my father was standing ready with a wooden kayak paddle to push me away in case of an ark flash. Nothing happened though.
    photo_2025-07-31_22-19-29.jpg
    I put the plastic piece of the cover I cut away earlier back into its former place with some duck tape.
  • The voltage difference between the upper bridge terminals was around 500mV at that point, if I recall correctly. So I connected my contraption for equalizing the string voltages. It consists of two contacts made from nickel strips with magnets inside of heatshrink tubing, connected over a fuse on each side that's definitely not rated for DC at this voltage (a cut corner, but better than nothing, I suppose), connected over flexible cable and single-strand copper wire to two Wago-connectors with exchangeable power resistors.
    photo_2025-07-31_22-19-42.jpg
    I only have 0.22 Ohm 5W resistors, but those are nice because they make the calculations easy. The resistors can handle 5A at a 1V drop, so you can put as many of them in series as you need with one resistor per volt of difference. Once you are below one Volt, you can use the inverse voltage as the number of resistors you need to put in parallel to draw 5A. At 500mV I started out with two resistors in parallel and went up to three resistors in parallel at 300mV and directly went up to 5 resistors in parallel at 200mV. The voltage dropped faster than I initially assumed. After about half an hour iirc I was down to 200mV and another half hour with 5 resistors connected later the difference was only 30mV. At that point I installed the bridge completing the upper string and then disconnected the magnets. You might wonder why I didn't equalize the strings at the HV box side like you would do with smaller batteries (at least I wondered how to do that safely before thinking about it more). I simply wanted to avoid the hazards of arc flash and electrocution that arise from working on "high" voltage in a small area. Dropping a tool there or slipping could be catastrophic. When equalizing two strings of batteries, you form a circuit where current flows between the strings, but obviously also through the strings. That's why it doesn't matter where in the circuit you place the equalizing resistor, even if it might seem unusual at first.
  • With the electrical part done, I reinstalled all bolts holding the modules down. I used a rattle gun at the lowest setting and tightened the bolts by feel. I didn't want to put too much torque on them as they are screwed directly into the aluminum bottom.
  • Finally, I put the vacuum-formed plastic cover back on. Many bolts didn't fit well into their holes and it was hard to fit a socket between the bolt and the plastic cover. I had to tighten some bolts by hand.

Notes:
I torqued all electrical screws to 18Nm. That's likely too much, as the flexible busbars were bent a little bit.
I broke the clips on most of the plastic cover over the busbars. I don't think they are meant to be reused. It shouldn't matter, because the lower ones can't move anyways and the upper ones are held in place by duck tape.
If you do use duck tape (which I don't recommend you do), it's a lot easier if you don't have to prepare the pieces with rubber gloves on, so a second person would help a lot here.
Ideally, you should use isolated tools. I don't have those, but I carefully planned all steps so I didn't have to use them.

That's it for now, the battery is still sitting on blocks on the ground under a tarp. The weather hasn't been great lately. And when it was good, neither my brother nor my friends (to everyone stressed out preparing for "Mathe 3", I'm rooting for you all! You can do it!) had much time. Installing the battery with floor jacks is definitely a job for multiple people. I am currently desperately procrastinating on starting my bachelor thesis so I really want to get going again. Maybe the weather improves soon.
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Re: [WIP] StreetScooter Repair and Reverse Engineering

Post by evMacGyver »

What OBC does this one have? Could it be same as here:
viewtopic.php?t=4608
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Re: [WIP] StreetScooter Repair and Reverse Engineering

Post by Jacobsmess »

It is and gb993 was actually the provider of the CAN information so has been a massive help on that front.
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Re: [WIP] StreetScooter Repair and Reverse Engineering

Post by gb993 »

I've actually managed to get 2 of my vans back up and running again so am happy to do some data logging and decoding if needed at all for any others here.
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Re: [WIP] StreetScooter Repair and Reverse Engineering

Post by gb993 »

Heye wrote: Thu Jul 31, 2025 10:18 pm Installing the battery with floor jacks is definitely a job for multiple people.
We found 2 trolley jacks, one in opposite corners the way to get the battery up and down.

We also used a wooden euro pallet underneath the main body of the battery to 1. Keep it off the floor for easy lifting and 2. To reduce the distance on the event of it dropping.

If you have a screwdriver that fits the holes on the battery case and use it to help line bolt holes up, it's not too bad to refit.
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Re: [WIP] StreetScooter Repair and Reverse Engineering

Post by Heye »

I appreciate the advice! We managed to get the battery installed in the car again. The procedure was much easier than I was worrying. We were very lucky that we had almost no rotational misalignment, so some adjustability in two directions was all we needed. Here are some pictures:
photo_2025-08-07_16-36-44.jpg
Notice the broomsticks we used to roll the battery under the car.
photo_2025-08-07_16-37-11.jpg
After lifting the top of the battery inside the cavity, we but it back on blocks to finely adjust its position.
While adjusting the position of the car in the direction of travel (resting it on the blocks worked really well), I noticed that the parking brake has almost no effect. Oh well. Probably nothing I can't fix. Final adjustments while putting in the bolts were done with a crowbar against a woodworking screw clamp on the frame.

Sadly, the car neither drove nor charged. The dashboard display says I'm at 56% charge now, which sounds fine. After connecting the EVSE, contactors clicked and the charge port LED indicated successful charging, but the current (as reported on the CAN bus) was a 0A. Possibly, the OBC (ACDC in StreetScooter terms) is broken. But I was expecting that, since I bought the car as "driving, not charging". The HV cabin heater works as well. A little too well, maybe. It either has a huge thermal mass or there simply is no way to fully turn it off once turned on. Running just the fan for multiple minutes didn't seem to make the air any less hot. While debugging the heater, we found out that disconnecting the 12V battery while the car is running (or even "shut off") doesn't actually do anything since the onboard DC/DC connector keeps supplying 12V and the HV contactors stay closed. This might be a problem, since the official way for emergency services to disconnect the HV battery after an accident is to cut the 12V cables! For now, I will assume (and later verify) that the cable coming from the DC/DC converter runs along the battery cable so it will be cut at the same time.

I can't put the car "in gear" and I can't start it. It says "Press Brake to start" and when I do that it just says "Werkstatt" (Workshop in German). Additionally, a red P in a circle is lit on the screen, indicating a malfunction in the parking lock. This might be the reason for the car not driving, but I would assume that it can drive even if it can't be safely parked? We can pull it around without issues, so it definitely isn't engaged.

At this point, I think I should read out / reset the errors in the VCU. The DBC file indicates that StreetScooter does use UDS, but it doesn't say which content so send as UDS messages. I contacted the only local shop that works on StreetScooters and they told me that they use a special diagnostic tool made by StreetScooter to read out the diagnostics and could read it out for me for 50€. They were shocked (shocked!) that I do any work on my own EV ("No, you don't! That's extremely dangerous! It has a high voltage battery! You don't have the certification!"). So I will need to be careful what I say around them. Because I would have to rent a trailer, it would cost me more like 100€. Before I spend that money, I definitely should build a reliable CAN logger with a big SSD...

I will also have a closer look at the CAN dumps I took. While I was inside of the car, nothing looked too out of place (other that the error messages the VCU sent to the dashboard regarding the parking lock and the "Workshop"), but maybe there is more I didn't see.

Regarding the OBC: I'm not sure that it's actually the same, I think it looks different visually:
photo_2025-08-07_17-17-25.jpg
photo_2025-08-07_17-19-11.jpg
That's it for now, I hope you all have a nice weekend!
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Re: [WIP] StreetScooter Repair and Reverse Engineering

Post by muehlpower »

Since I may need to build another show vehicle with Street Scooter technology, it would be great if you could measure your battery. The overall length and width are particularly interesting, because the battery in my chassis is installed transversely behind the seat. In the photos, the battery looks different from the early model I used.

Gruß aus Bayern
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Re: [WIP] StreetScooter Repair and Reverse Engineering

Post by gb993 »

For getting it started, any time I've had the 12v off, I essentially have to cycle the ignition on and off several times before the vehicle will drive.

On mine, the instrument cluster/buzzer makes sound once it is ready to drive.

On my one with dead obc it doesn't prepare to charge at all and visually appears to stay initialising.
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