Bringing a VanMoof X3 or S3 Back to Life – Part 1 – Smart Cartridge

The VanMoof X3 was a perfect city bike for my partner but, after being stashed over winter, the battery had gone flat and it refused to take a charge. When this happens it’s possible that the bike’s charging circuits are detecting an “overly” discharged battery and are trying to protect the Lithium cells from damage. VanMoof’s bikes are technically clever but many of the components are proprietary and options for replacing or repairing parts are pretty thin on the ground.

In this technical support document, VanMoof let slip that there is a small secondary battery responsible for the electronics in addition to the primary battery used for driving the motor. I had a theory that perhaps this battery had gone flat which was in turn preventing the electronics in the Smart Cartridge from kickstarting the charging circuit for the main battery.

In this post I will lay out the steps and tools required to extract and deconstruct the Smart Cartridge from an X3 and recharge it’s small internal battery. These instructions, while not identical, will be understandable for owners of a VanMoof S3 not just the VanMoof X3 we own.

Before you start, follow the first half of this document from VanMoof to remove the Smart Cartridge from your bike. The video below is taken from that page. If you’ve removed all of the screws shown below but the Smart Cartridge still doesn’t want to slide out, remember there is one screw behind the seat tube that’s very easy to overlook.

Once you’ve got the Smart Cartridge free from the bike frame, you can take it over to your workbench for dismantling.

A Smart Cartridge from a VanMoof X3.

The real bulk of the Smart Cartridge is forward of the seat tube, so we first need to remove the extension that holds the rear light. A small flat-bladed screw driver can be used to turn the two plastic screws by 90 degrees, freeing the housing that hides the rear light’s power connector. The rear light can now be unplugged and removed. The rest of the seat tube extension can then be removed using a T6 torx screwdriver. There are two screws holding the top and bottom of the extension together and another two that hold the extension to the Smart Cartridge.

Now the Smart Cartridge has been stripped down to just the “brain”, you can open it up by removing the 8 T6 torx screws around its perimeter. When you separate the top from the bottom be careful as there are two sets of quite fine cables connecting the halves.

An opened VanMoof X3 Smart Cartridge showing it's circuit board and internal battery.

The main circuit board is connected to the dot-matrix display via the ribbon cable. This can be disconnected to give you more room to work, but is not necessary as long as you are careful not to damage the cable. The small Lithium-Poly cell is connected by the bundle of red, yellow and black wires. It can be removed from the top case by releasing the four clips. Unplug the connector from the main circuit board and you can remove the cell from the Smart Cartridge.

Carefully pull back the piece of foam and you’ll reveal the cell and you can read off its details. We will need this information to find a datasheet that can tell us how to charge the cell safely.

The internal battery of a VanMoof X3 Smart Cartridge with the protective foam removed revealing the battery's specification.

Searching the web for “iGreen Tech” didn’t give me any decent leads. There appear to be a number of companies around the world with that name, none of whom seem particularly relevant. Searching for “iGreen Lithium” does find one company that might be close, but it still didn’t get me any closer to a datasheet.

Instead, I tried a brute force search for all of the numbers on the cell, “922543 1050 3.7 3.89”. That was much more useful. It appears that 922543 is some sort of standard reference number for this kind of cell as many different “manufacturers” have sold 3.7V 1050mAh Li-Po cells with this code. I say “manufacturers” as it appears that a company called Shenzen BAK Technology will white-label their cell with your brand if you buy enough of them.

Stock photography of a Shenzen BAK battery which matches the specification of a VanMoof X3 Smart Cartridge's internal battery.

Further digging reveals that the Dubilier 922543 is compatible with the BAK 922543, so the datasheets should be similarly compatible. Finally, with all that in hand, I managed to track down a Dubilier datasheet for their 922543 Li-Po cell which matches our 3.7V 1050mAh specifications.

With that datasheet available, it’s time to figure how to use the information contained within to charge the cell. This video from Dave Jones of EEVblog goes over all of the details on how to charge Lithium-Ion and Lithium-Polymer cells.

Having consumed all the theory behind lithium charging another video, again from EEVblog’s Dave Jones, has practical advice on charging Li-Ion and Li-Po cells with a bench-top power supply.

I have a NANKADF 30V 10A programmable supply, so following those videos combined with the datasheet, I set the power supply to 0.53A CC and 4.20V CV mode and connected the cell. At this point there is a danger that the cell may have been damaged by the excessive discharge and recharging it this way could result in a battery fire. I monitored the power and temperatures over the recommended 3.5 hours charging period and observed nothing untoward, indicating that the cell was good to put back in to operation.

Now the small Lithium-Poly cell is charged, reverse the tear-down process and rebuild the Smart Cartridge. If everything’s gone to plan the Smart Cartridge should spring back to life and indicate that it’s in “Shipping Mode”. There’s a good chance your bike decided to enter this mode when it originally detected the battery draining to try to prevent the batteries from getting “dangerously” low.

A repaired Smart Cartridge from a VanMoof X3 indicating it is in Shipping Mode.

To get the Smart Cartridge out of shipping mode, follow the 3 step instructions in this VanMoof support document. That is, after re-inserting the Smart Cartridge in to the bike’s top tube, plug in your charging lead, press and hold the bike’s power button for two seconds, then short press any of the bikes handlebar or power buttons.

If an “unsafely” discharged Smart Cartridge was your only problem, your bike should reboot and begin to charge the primary battery in the bike’s down tube. If, however, your primary battery was similarly discharged to an “unsafe” level you’ll see the status light on the charging brick pulse red as it tries to start charging, but quickly return to green when the charge fails.

In Part 2 of this series, I detail the steps required to extract, dismantle and refresh the main battery pack.

Update — 2023-11-13

When I wrote this post, I didn’t want to include anything about how I physically connected my power supply to the battery as it was a bit of an off-the-cuff hack. However, I’ve since received a couple of comments asking from more information.

I just snipped the legs of a spare LED, bent them 90°, then inserted them in to the positive and negative places. The square profile of the LED legs meant they wouldn’t spin once connected, removing the risk of them shorting against each other.

I didn’t connect the centre pin as I didn’t have any facility for monitoring or logging that data. Since I was already using a CC/CV process and monitored the temperature of the cell during charging, I didn’t feel it was worth the extra effort.

A close up of the crocodile clips from a power supply connecting

I was worried that the “random” size of the legs might have subtly damaged the spring terminals within the plug, so I didn’t want to recommend that as a solution more widely. It appears that those batteries use standard Molex PicoBlade connectors which have an aperture of at least 0.5-0.7mm, so a standard LED leg of 0.5mm should fit just fine without any worry.


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9 responses to “Bringing a VanMoof X3 or S3 Back to Life – Part 1 – Smart Cartridge”

  1. […] Part 1 of this series, I extracted and deconstructed the Smart Cartridge from my partner’s VanMoof X3 with the goal […]

  2. David Ellington avatar
    David Ellington

    Hi Mike, great blog, I found it really informative and helpful. One question though – when you connected to the Lab power supply, how did you connect it – through the fitted plug? or did you bare the red and black wires and connect crocodile clips to them?

    1. Mike Coats avatar

      Hi David,

      Thanks for your feedback and question. I’ve included an update at the end of the post to answer your question. Luckily, I still had a photo in my archives to provide some more detail too.

      Cheers,
      Mike

      1. David Ellington avatar
        David Ellington

        Awesome, thanks – based om the information on your blog I have successfully recharged the battery in my smart cartridge. Unfortunately I’m still getting an error (ERR 6) so I guess I’m now going to move onto your Part 2.

        1. Mike Coats avatar

          Congratulations and commiserations! Good luck with the battery pack. It’s no more involved than the smart cartridge; it’s just a bit bigger so it takes a good bit longer to charge.

          Unfortunately, I’m now dealing with the dreaded Err44. If I had a spare/working e-shifter I’d be inclined to run a datalogger on the wires and try to reverse engineer the communications between it and the smart cartridge to see what I could come up with. Unfortunately, they’re like hen’s teeth.

  3. Elwyn Davies avatar
    Elwyn Davies

    Hi. Could you tell me which wires you connected to the charger please. I assume it was the positive and negative, and did not connect the third wire?

    1. Mike Coats avatar

      Hi Elwyn,

      I’ve updated the end of the post to address your question. I only connected the positive and negative terminals, leaving the centre pin unconnected.

      Cheers,
      Mike

  4. Chet avatar
    Chet

    Hi Mike excellent write-up. It has given me the confidence to attempt repair. I got a similar bench power supply as in the picture.

    When charging, it started with cc-mode at 4.2v & 0.53A. How do I change to cv-mode as shown in the other picture
    Thank you

    1. Mike Coats avatar

      Hi Chet,

      Thanks for your kind words, I’m glad you found this useful. To answer your question, the power supply takes care of the switch-over from CC mode to CV mode automatically.

      When you set the voltage and current values you’re in effect setting the maximum values the power supply will drive. When the cell is flat the voltage will be low, so the current draw will be pinned against your 0.53A current limit which puts you in constant-current mode. Once the cell reaches 4.2V the voltage limit has been hit so then it’s in constant-voltage mode.

      Cheers,
      Mike

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