Solve the battery or ignition problems of your xiaomi scooter

This tutorial aims to help people who have scooter power on issue. It seems that some owners of scooters dating from 2016 have problems due to poor management of Regenerative Braking system . We advise all those who have one to put “WEAK” the level of ” Range of charge mode” in your ninebot app or mi home app

This article is a synthesis of infos found dealabs  (thanks b18685) and forocoches  for pictures

1er case, the easiest

Disassemble the protection that protects the battery pack

Without disassembling anything else, just unplug the large red and black wires from the green round control console (no need to remove the battery!)

  • Connect the power supply to the scooter as if to recharge and wait 30 seconds
  • Disconnect power cable
  • Reconnect the large red and black wire connector
  • Press the start button on the scooter

If this works, close the battery cover and set the” Range of charge mode” setting to “weak” on the ninebot or Mi home app until firmware version 1.31 is available. You can adjust your rear brake manually so that it is a bit more efficient without rubbing on the disc.

2nd case more annoying but feasible: connector desoldered

A connector has been desoldered or made a bad contact (red circle, we do not see all of them in this picture)

Check their connection and redo the solder especially by unplugging ALL the wires that connect battery to the control console and of course by locating them beforehand with a small drawing (no need to disassemble the battery)

Also check that cables are not damaged

  • After welding, reconnect the wires
  • Connect power cable for 30s
  • unplug power cable
  • Power on the scooter
  • If she turn on close the battery cover

3rd case / A fuse has blown

motor brake when the battery is 100% sent too much juice during a throttle lag) (if you are in “middle” or “strong” mode and firmware version <1.31) the system has blown the “Z” fuse ”

Detailed tutorial coming soon




227 thoughts on “Solve the battery or ignition problems of your xiaomi scooter

Add yours

  1. I’m at dead end 😦
    Xiaomi support is terrible. I still receive this error (BMW password is wrong(22)).
    Though through the app I receive cell voltage to every cell, everything, temperature sensors.
    But can’t run on full power only to 12.5 and I receive 2 long and 2 short beeps constantly.

    I’m considering re soldering microprocessor maybe? Any advice will be very wellcome


  2. Assuming you still have your original controller board, it should know the BMS password. If not, it must have got corrupted. The only thing I can suggest is to contact Ferry in Moscow who have cracked the BMS code and know how to initialize the controller.

    I’m not quite sure of their contact details but it like Whatsapp to +7-904-219-51-32 should work. Otherwise, look on Youtube for the videos uploaded by Mini and see if there are contact details in those.

    They are a commercial organisation so will want to charge for repairs


  3. Hey mates! I have kind of a weird problem with my xiaomi scooter. Maybe you can have a look at my video and tell what I could do to solve the issue. The scooter does not getting turned off. And it’s in kind of a loop and not useable.


    1. Paul, the green light on the controller board indicates a loss of communication – in this case almost certainly to the handlebar control panel. Either you have a broken connection between the main controller and the handlebars, or the handlebar circuitry is faulty.

      But first, have you tried a complete reboot? To do this, disconnect the plug with the thick black and red wires from the controller. This removes the battery power. Then re-connect and see if you still get the problem.

      If you do, check the 4-pin connector on the controller and then you may have to undo the handlebars to get at the connector at that end of the wire. See the photo at where it becomes obvious what you should look for.

      If all that checks out, then I have no more suggestions.


  4. My scooter randomly stops and make 3 short beeps and one long. This may happen twice in a day or with 10 days of time difference. Battery voltage is always OK. Cables and connections are ok. What I usually do is to reset the battery and some how the problem is solved until next time. Maybe I reset 5 times or 50 to solve the issue. What I suppose that could be happening is that a sensor is not working properly. Anybody knows which sensors are and how to check if they work OK? Thanks!


    1. Hi Marce,

      I received my scooter yesterday and I got the exact problem like you. Whenever I’m putting the scooter on, I have 1 long beep followed by 3 short beeps. Were you able to figure where the problem was located ? I’m thinking about a misconnection in the handlebar. thanks for your insights.


      1. Hi Kirikou,
        unfortunately I did not resolve the issue. What I did is to check the connections and battery terminals, this was OK. Then I just disassemble the battery pack and the BMS controller. I checked the fuses (temp and the other) and both are OK. What I noticed is that one chip of the BMS was too hot, for sure this is not normal. Just is case, I removed one battery cable in order not to let the electricity reaches the BMS controller board. I believe that this board is not usable or has a serious defect. If you have any clue of your issue, please share. Thanks.


  5. Hi Peter.
    I have a mijia scooter.
    but it’s not working because fail of BMS.
    I am trying hard to find the cause.
    Do you know this part in the BMS board?
    It making is L04A DW location no is U4 and U5.
    They are heating at connect battery.
    they remove at the pcb BMS red led on off repeat.
    I think they are fault then I want know spec of U4 and U5.


    1. Shalom, I don’t have a BMS board on the bench at the moment. As I recall, U4 and U5 are the two little square integrated circuits with 8 pins each. Is that right? Next time I take a battery to pieces I will see what the part numbers are.


    2. I’m sorry but U4 and U5 can’t be that logic gate HD74LV2G04A I’ve desoldered one and follow tracks seeing that gnd (pin 4) is routed to B9 that is directly connected to B9 balancing port of battery pack.
      I don’t know why this manufacturer is marking their chip like other ones (same package and same marking). First time ever I see that, I think Chinese market do things on their own way…..


  6. Hello everyone

    I have the exact same issue as amarinpietro (october 6th 2017).
    The leds dont flash at all, and one of the connector on the side of the battery is broken.

    As I’m new to soldering, is it normal that when I put the broken electrode back in contact with the battery and the central electrode, that it creates sparks ? Can I safely proceed to soldering ?
    I’ve also put some flux on the contact.

    Thanks for your help.


    1. It could be OK, or it might not be!! It’s difficult to tell without a good photo of the broken parts. Each of the 10 cell packs is made up of three batteries in parallel and if the connection between these three breaks, then they may be at different states of charge (voltages). In this case, when you make the connection again, the higher voltage cell with try to charge up the lower voltage cell causing a spark as the electricity starts to flow. But if the break is between two of the 10 cell packs, then a spark is wrong.

      Can you post a clear photo of the broken bit please?


      1. Where that break is definitely must be connected to the battery underneath. The sparks must as electricity is flowing from the higher charged cell(s) to the lower charged cell(s). It’s quite difficult to solder directly to the nickel base of the cell because you have to be quick so as not to overheat the battery and yet there must be enough heat to get the solder to flow and not just form a blob on the surface.

        Scrape the surface well to expose fresh metal, apply a smear of good flux and then heat quickly with a reasonably powerful soldering iron and some fresh solder. Hold the broken tab down with a screwdriver held in your third hand (!) as you do this.

        Good luck


      2. Hi Peter,
        So I’ve managed to solder there and I think it worked because that individual battery quickly heated, which I think is due to the charging process (which scared me quite a lot at first), but it’s back to a normal temperature now.
        However the LED are still not blinking, is there a way to turn it back on ? I’ve just bought a multimeter, could you please tell me which electrodes to test ?

        Thanks a lot for your help.


      3. I’m a little worried that the battery heated but it could be OK if, for instance, it was discharged and needed to be charged by the other two cells in the pack.

        You can try rebooting the BMS. Right by the blue LED that is not lit (!), there is a tiny button. Press and release this and the blue light should start flashing at one second intervals. If you see the red LED flash four times and then stop, there is still something wrong.

        You can use your multimeter to check the cell pack voltages. There are 11 terminals on top labelled B0 through B10. If you connect the black lead of the multimeter to B0 and the red one to B1, you will see a voltage of, say, 3.6 volts. That is the voltage of cell pack 1. Note that down. Next, put the black multimeter lead on B1 and the red one on B2 and write down the reading as cell pack 2. Repeat until you have all 10 cell pack voltages. The last one will have the black lead on B9 and the red lead on B10.

        Ideally, these voltages will all be equal to within about 0.02 volts but in your case, I would expect cell pack 3 to have a different voltage because of the repaired break. Once the BMS is working again, you can charge the whole battery and the voltages will even out (you may need to charge and discharge a few times if there has been a big difference). When the scooter is working, you can see all 10 cell voltages reported on the MiHome app if you run it on an Android device. These are an important diagnostic because in a working battery they should all be equal.


      4. Hi Peter. I tried pressing the button but nothing happened.
        My measurements are:
        B0-B1 : 0.06
        B1-B2 : 1.26
        B2-B3 : 0
        B3-B4 : 3.62
        B4-B5 : 3.62
        B5-B6 : 3.62
        B6-B7 : 3.62
        B7-B8 : 3.62
        B8-B9 : 3.62
        B9-B10 : 3.62

        What do you think? I guess B3 is simply empty, because I can measure the voltage from the B0 to B10 (which shows 26.6V) as well as measure from the black electrode to the red electrode.


      5. However, when I put the two multimeter leads in the two plugs that connect to the motherboard, it only shows 2.37V.
        When I measure the voltage between the black plug and B10, I get the full voltage (26.6V) but when I measure from the red plug to B0, I only get 2.37V.
        Do you think there’s another problem with the black wire ?


      6. This does not look good, Arthur.. But first, do not worry that the voltage to the motherboard is only 2.37v – the BMS has turned off the supply because it can see that the battery pack is faulty. The actual power comes from the thick black and red wire and this should be 36v not 26.6v. This is the problem.

        There is something seriously wrong with the first three cell packs. For a lithium cell to read zero it is not simply empty, it either has a short circuit or it is ruined or is not connected so there must be another – or more than one break in the area between B0 and B3 so you should unsolder the thick black wire so that you can get the black plastic off all the way along – and on both sides. Look for more broken connections and re-make them.

        Do bear in mind that at the positive end of each battery, the terminal is very close to the outside metal container and it is vitally important that you do not make an accidental connection between the two. If you have done this on B3, it will not be good for the battery.

        I feel fairly certain that B0 has got disconnected but you will have to look closely at all the connections, both to the bent over metal tabs and where the metal strips are spot welded to the individual cells.

        In hindsight, I should perhaps have suggested that you find someone nearby who is experienced with soldering. In this environment of high power batteries, a dropped blob of solder in the wrong place can cause such a short circuit that I described above.

        Please look very carefully at all the connections to do with the first three cell packs, i.e. 9 cells.

        Good luck!


  7. Hi,

    I just received my Mijia M365 and right off the box it gives me an error code 18 (hall sensor error), so the motor doesnt run.

    Any idea what I should do next?


    1. I’ve not seen this problem but what I would do before sending the M365 back to the store is to take the cover off the bottom as shown in the first case at the top of this thread and check that the connectors to the controller board are properly plugged in. The Hall effect sensor is connected by one of the little white plugs on the left of the photo.

      If it’s not this, then let’s hope the problem is not that the sensor has failed because I would think replacing it is something that should be done under warranty.


      1. I have similar problem. It turns on beep twice and No reaction throttle. I checked board conection but No results


    1. I’m sure it would be possible to use a different chemistry LiPo battery – IF you can crack the BMS firmware to allow for the different charge/discharge characteristics. For instance, batteries based on Lithium Iron Phosphate have a fully charged voltage around 3.7v while the lithium metal oxide batteries are fully charged at 4.2v. And other chemistries need different charging rates.

      For more information, see:


  8. Any help would be great, scooter will not power up. Have tested all of the connections, the voltage coming out of the thick red and black wires was 3.6 I believe. I checked the fuse and get multimeter is changing from 1 to 0. I did notice that the board has 2 Z fuses on it and checked both. The only thing that happens is a red flashing light that flashes about 4 times when I plug the power in and then stops.


    1. Yes, the welded connection B0 on the battery has lifted as shown in option 2 at the top of this thread. This is the one nearest the back wheel. Do not be misled by the fact that you have 36v coming from the thick black and red wires. Connection B0 is for the battery monitoring and without this the BMS doesn’t know where to start so it shuts down. Repair this and press the little reset button next to the LED and you should get the blue light on again.


      1. I went back and checked the connections and you were correct. I resoldered B0 and voila!! The blue light came back on and I was able to turn on the scooter. The battery was low from the last time I used the scooter but I checked the Ninebot app and noticed I was only getting about 19km/h. Could this be because of low battery? I’ll wait for a full charge and check again. Thanks for pointing me in the right direction.


  9. Hello there! I am hoping you can help me. I had a problem with my M365 where the B0 contact came loose and I think it touched the scooter frame because there was burnt and melted plastic wrap. I managed to get Banggood to supply a replacement battery but when I installed it the scooter is still dead. The power button does not work, and there are no LEDs on the main controller board. The blue light is on the BMS board but it doesn’t seem like power is going to the main board. I tried the step 2 above in this post (unplug battery, charge for 30secs) but this did not work. Any suggestions? I thought maybe something to do with the BMS being paired to the main board? Is this the case? or do you think the main board has been fried? Thanks!


    1. Just a few points: is the blue light on the BMS board steady or flashing once a second? Can you confirm that the little 3 pin plug with green, yellow and white wires is properly connected (and the main plug with thick black and red wires of course). Do you have a voltmeter to check that there is 36-40 volts across these two wires?

      The BMS doesn’t need pairing with the main board; battery packs are interchangeable without fuss.

      Where in the world are you? Just in case you’re local enough for some assistance.


      1. Thanks Peter, I am now trying to remember what the blue light was doing. The scooter is at home at the moment. I am fairly certain it was flashing once per second. I was quite sure the green, yellow and white cable was secure too and the battery was at 36.5 volts. Good to know the BMS doesn’t need pairing but I am suspecting the main controller might be fried and possibly the LED controller too. Do you know if there is a way to test these components?

        I am in Australia. Is that close? 🙂


      2. Australia? Not too near; I’m in UK!

        I think I’m out of ideas. The next step would be to try substituting good components but only possible if you have access to another working scooter or spares, of course.

        If you now definitely have 36.5v going to the controller board, then I guess it must be faulty although I’m having difficulty imagining what could go wrong with a 10S3P battery pack that could cause damage to its load by itself.

        Next step? Find someone near willing to let you substitute your controller for theirs? Get Banggood to send a new controller or refund you?


  10. Hi guys,
    thanks god I’m not the only one having issues. Today after just2-3 days of usage, suddenly the scooter turned itself off and wont start anymore. When I press the button, the back red light flashes with what seems an error code: 1 long flash, pause, 8 short flashes. I have the latest firmware installed.

    What to you guys recommend? Do i have open the battery cover to check for the above 3 issues ?

    Thanks a lot


    1. Sounds like the usual problem of connection B0 coming loose on the battery. Follow the steps as in the second case at the top of this thread. B0 is the connection nearest the back wheel, i.e. at the top right of the large black label on the battery pack.

      Press this down with a finger and see if the scooter will power up. If it is the problem and the scooter is new, complain to the supplier. Otherwise, you will have to cut the plastic battery covering to get at the connection before soldering it.


      1. Thanks Peter, I’ll check the battery and get in touch with Tomtop, where i got the scooter from.
        I’ll keep you posted about this, for the sake of everybody’s knowledge.



  11. Hi Folks,
    here’s the situation: Output voltage from the two wires that connect BMS to the controller board is 3.6V. If I measure the voltage from the side of the battery pack, this is before BMS, and I get 38V. All cells are OK.
    So the problem is inside the BMS. I checked the fuse and it’s OK. I’d like to know what else to check, i read that there’s is a temperature sensor but not sure which is and how to check it.


    1. You say “all cells are OK” but are you sure that all 11 cell monitoring connections are OK? These are the tabs labelled B0 through B10 on top of the battery and do not affect the 36v you have coming from the thick black and red wires into the BMS.

      Without these connections, the BMS will think the battery is faulty and shut down the power. The most common connection to fail is B0 which is the one nearest the back wheel. Check it is making proper connection as shown in case 2 at the top of this thread.

      So many people think that if they have full voltage from the black and red wires then the battery connections must be OK. This is not true, the 11 cell monitoring connections must also be made.


      1. Hi Peter,
        yes cells are OK. I’ve checked all, B0 to B1, B1 to B2 and so on, all are OK. Also are firmly welded. Fuse is ok and I think I found the temp sensor, which marks 7,5 in the scale of 20k ohms. I don’t know if the temp sensor could be faulty. Is there a way to check it? I don’t know what else could be. The light at the BMS blinks two o three times in blue when I reset it, after turns to red, and after it switches off.


      2. The temperature sensor sounds about right if you’re in a warm place – about 32C.

        The light sequence you describe is typical for a B0 disconnection and shows that the processor on the BMS is running. It is possible that, when you put the meter test probes onto the tab, you re-make the connection temporarily. Could you try again measuring all the cell voltages but at the nearby resistors (they are very low resistance sensing components so it doesn’t matter which end you touch) and pay particular attention to the voltage from B0 to B1 measured at R5 to R1 (I think these numbers are right but I don’t have a battery in front of me).

        All 10 cell pack voltages should be equal within 0.02v of each other. Any larger differences means that there is a connecting problem with one or more of the 11 sensing connections.

        Oh, and one other silly thing: you get this pattern of lights if the thick black wire is not connected at all. The BMS gets its power through the sense wires but I’m sure you wouldn’t have disconnected it.


  12. Peter thanks for your comments. I didn’t understand if I could try again measuring all the cell voltages but at the nearby resistors. I’m not sure which or where are the nearby resistors. Thanks again for your help.


    1. I don’t know how to post photos on here to show what I mean but if you join a Facebook group called Electric Bikes Scooters Longboards, I have posted some photos there.


  13. Peter,
    in the facebook group I just uploaded two videos of my issue. I checked again all the cells, I have exactly the same measure between all, this is 3,8V. Fuse and temp sensor seems to be OK also. I don’t have any idea what could be faulty. Any clue is appreciated.


  14. hi, i just received my brand new m187 youth edition and it won’t turn on.. i opened the battery case, a red light flashes continuesly, and i have 3.1V. when i’m plugging the charger nothing happens, i tried to reset the bms but nothing xbanges, do you have an idea? thanks


      1. Hi Peter, thank you very much for your answer, that was indeed my idea but I wanted to be sure first that it was not an easy problem to solve (it took almost 2 months to reach me from China, i didn’t want to wait 4 months before having a new one…) So do you understand what’s happening? thanks a lot!


  15. Hello Peter,

    I am located in London and was wondering if you could help me fixing the non power on issue?
    Unplugging the battery pack did the job once but after one ride, the issue is back. The soldering looks OK to me. Could I possibly send it to you and pay for the eventual fix? Thanks. Guillaume


    1. What lights are lit on the battery pack, Guillaume? Is it a blue light or a red light – flashing or steady? First test would be to press down hard on tab B0 (the one nearest the back wheel) and see if the scooter will then power up while you are pressing.

      If you can’t get any results, best thing to do would be to join the Facebook group We Are Electric and then we will be able to exchange private message so that you can send the battery to me.


      1. Thanks a lot Peter for answering.
        When doing the battery pack Unplugging procedure the red led flashes 4 times then stops.
        I did try pressing hard the B0 contact several times while trying to power on with no luck. Will join the group now. Kind regards.


  16. hye, i got the scooter yesterday & right out of the box it beeps permanent 2 times long and 1x short. i’ve searched a bit and found out that this seems to be error 21 battery communication error

    and know? i dont have any clues to fix that. it dont charge, the battery tab of the ninebot app shows no information from the battery.

    any ideas how to fix this? i’ve checked the connectors (fine) and done a firmware update (1.33 to 1.34) but the problems persist

    thank you


  17. hi, im having an even bigger problem, some of the conectors came off but I soldered them, everything was going great but then the bms won’t turn on and its getting warm but the bottom, even when the only thing connected is the white plug that comes from the top of the battery (the one that connects the two blue black flat cables that are connected to the blue connectors on top) , any ideas??


    1. The BMS will get power from the white flat connector even if the the thick black and red wires are disconnected. Do you get any lights lit if you press the little reset button next to the LEDs? In particular, do you you get the red LED flash four times and then stop?


  18. Hi,

    After 4 months, I am having a weird problem. After a ride and turn off, the scooter does not turn on anymore. No light signal. At first time, I thought it was a battery connection problem, but if I plug the charger, everything works again. I check the battery voltage when battery full (around 41V), I also check the battery cells voltage and it seems correct as well.
    I also noticed a great decrease of autonomy, yesterday only 10kms! Currently, it is quite cold outside.

    I do not know what to do as it do not seem a connection issue. Any clue from someone?




    1. Hi there Matt. I have had a similar experience recently, and also wondered if it had to do with the cold weather. After use, sometimes it does not switch back on, but like you said, if you plug it in (which resets the BMS without having to get inside) it seems to work OK again, until the next time. I have also experienced wrong readings of remaining charge, which usually sorts itself out after a ride (I’m guessing the battery is warmed up to the point where it is fine again).

      I was worried that it was a problem with the battery (as this is my second battery now) but seeing your comment is leading me to believe that these things do not like the cold. I couldn’t find any information about this scooter and the cold in particular, but I found some information on electric bikes which use the same kind of battery, and apparently they do not like the cold so much either.

      Hope this helps in any way!



      1. Lithium ion batteries certainly have less capacity in cold weather but I believe the problem you both describe is a battery connection – but not the usual one.

        The batteries are made up of 30 cells formed by 10 packs of 3 cells in parallel. In any one group, if a cell gets disconnected, that pack will only have two thirds of its normal capacity. This means that when charging, that pack (of only two cells) fully charges first and the BMS sees that it has reached 4.1v and stops any further charging even though the remaining 9 packs are not fully charged. Then, when you ride the scooter, the faulty pack runs down first and once it’s under 3.2v, the BMS will not let the scooter power up – although it lets the power continue if already powered up.

        You can tell if this is the problem by using the MiHome app which will display the 10 cell pack voltages. When charging, you will see one pack reach 4.1 volts long before the others. When partially discharged, the cell pack voltages may seem to be balanced but on discharged once again the faulty one will have a lower voltage than the other 9.

        To fix this, you need to remove the black plastic insulating strips from each side of the battery to expose the nickel interconnecting ribbons. Having identified which cell pack is faulty from MiHome, you can try lifing the strip away from each cell – on both sides. If it does lift away, then you will need to solder it back – but it’s not easy soldering nickel to cells, especially as you mustn’t overheat the cell.

        Nickel is not a very malleable metal when cold and vibration can cause the strip to snap where it has been formed into a kink. Worse, of course, if you have solid rear tires!

        Hope this helps


  19. Ok, just did some additional tests.

    – Yes I have a red LED on BMS when cable plugged.
    – Just checked the monitoring of the cells during charging, everything seems to run fine. All the cells progressively get charged until around 4,2V.
    – Also checked the cells when the scooter is running. Also no problem, the discharge seems homogeneous.
    – Turn off – turn on. Run the scooter. The cells voltage are all closed. Battery percentage around 91%.
    – Turn off again – turn on. Battery percentage is 62%! I run the scooter and check the cells. Cells pack 1 is less than 3,2V while all others are around 4V.
    – Turn off – turn on. Battery percentage is 82% now (??) and the cells pack 1 is around 4V…
    Also encountered a case where the scooter turn off during a run, and the cells pack 1 was around 2,5V.

    I do not understand everything, but seems obvious I have a connection issue on cells pack 1. I am going to check. Thanks again for your help.


      1. One thing I did just now, with the same issue the other Matt is having.

        I poked a hole in the plastic area around the BMS reset button after the M365 doesn’t come up again, and it works afterwards… So my question is:
        ‘Why does the the Xiaomi not allow ignition unless the BMS is reset either by the recharger cable being plugged in or the BMS button being pressed?’


  20. Hi there Peter, thanks again for your speedy reply. (though I was dreading a response such as this!)

    This does sound like the problem, but I have never had any luck with connecting the scooter to the Mi Home app, only the Segway one. (which displays everything as being normal when fully charged, but I’m guessing that the Segway app would not flag any problems with individual cells?)

    When trying to connect to the Mi Home app just then, it briefly managed to find the scooter, but when trying to connect to it, it gave me a -29 error. And now it won’t find the scooter at all.

    I guess it’s better to get this app to work first before further damaging the plastic cover for the battery to check the connections, so I will keep trying.

    Also, forgive my nosiness, but I noticed you gave someone your FB address to PM you, and I was wondering if you are based where the name suggests?

    Thanks for your time, and for the detailed explanation,



  21. is there a troubleshooting available for the error Codes? My Scooter beeps 2 long and 1 short beep. Error Code on ninebot app is : 21. Can anybody help?. Battery is ok.

    Thanks a lot



  22. Hello,

    I have an issue with my m365 that I cannot resolve, unplugging all the cables also did not help.
    I was on the maiden ride of the scooter, braked and couldnt speed up again. Now i get 2 short beeps followed by 8 long ones.
    It connects with my app and is unlocked.

    Any ideas?


  23. Error Code 21 means: Battery Communication Error. I checked everything in this Thread: BMS Fuse, Contacts, etc.
    Battery has 42 Volts. When i switch the scooter on, it beeps. The Throttle Funktion is only 10 %. Seems like a Protection Mode. Can anybody help? Error Code 21?

    THX Carsten


  24. Hi,

    I have just recently experienced a problem where I have lost power but the scooter still works. I cannot reach full speed but goes along around 10-11.5kph. It happened after I jumped off and walked the scooter across the road as it was a red light but green for pedestrians. Jumped back on, kicked off and put my thumb on the throttle.

    Any luck/chance in getting this resolved?

    Thanks in advance.


  25. Hi people,
    The BMS I have is full of issues..I’d like to know if I can simply buy a new one and replace it, or somehow the controller checks something (serial # or other). Thanks!


    1. Hi Marcelo,
      I checked signal transmission when you startup scooter between BMS and MOTOR controller(with interface usb/rs232). I think it’s serial transmission UART,but I don’t find the good speed rate !(it seem to be 128 kb/s).So I just tell you ,BMS send message to Controller when you startup system.


      1. Stef, the serial transmission between the controller board and the battery (and between the controller and the BT module in the control panel) does not use a UART. You are right that it is a serial interface but it is bi-directional (not separate transmit and receive wires). The other wires are ground and clock. It conforms to the IIC standard (see for more details)


      2. Thanks for your inputs but I don’t have such technical knowledge. My question is if I can just buy a new Battery pack (which comes with the BMS board) and just simply replace it, or some adjustmens are needed. Thanks!


      3. Stéf, I’ve not had cause to try to intercept this data so can’t say definitively. Raspberry Pi users tend to use white=ground, green=SDA, yellow=SCL but that doesn’t mean that the Xiaomi engineers did so too.


      4. Hello Peter,
        Thanks for informations .No I don’t try yet,I will test at the end of may….i will keep in touch…for the moment I have problem again with battery’s connexion ,the scooter doesn’t power on!


    2. I’m not aware of anywhere that you can just buy the BMS board; it comes as part of the entire battery assembly. You can change batteries without any problem with serial numbers or passwords.

      You could, however, look at a third party product that does the same things as the BMS


      1. Thanks Peter for your informations of I2c,So I will try to connect I2c interface to see transmission information between BMS and controller.
        Do you know where is Ground SDA ans SCLon Wire (yellow,green ,white)?


      2. Hi…No i haven’t done the probing test yet!I will test on my scooter at the end of may! i will keep you updated.


    3. Just buy a new one. No compatibility issues. As I said “You can change batteries (packs) without any problem with serial numbers or passwords”.


  26. hi peter i have a problem on my m365 scooter it shut down and no power at all but i did the 1st solve to unplug the red and black wire and connect the charger its ok everything back to normal but when i turn upside downmy scooter to test run when i turn it on theres no powerat all i cant turn it on what is the problem of my scooter can you help me on this by the way i open it up again to check do the same thing i notice when i plug in the charger he red light on the bms it flash 4 times and after that no more please hep thanks


    1. “I think you should try option 2 this time. The symptoms you describe are often caused by connection B0 coming disconnected. That\’s the one nearest the rear wheel.


      1. Hi Peter,

        I think that my mosfets on my BMS board are dead. I’m trying to replace the MDE1932 and both MDD1902 as you did, but it is a nightmare to find it.
        Could you please help me ? Maybe you still have some of them to sell ? (I’m leaving in France). Thank you


  27. Hello, I have an issue with my scooter, ..hope you’re goona help me.. 😀 Sometimes it switches off by itself and I cant switch it on. The only way to swich on is to put charger in for about 5 seconds and then it is O.K… any ideas to fix this problem?


    1. Hi alda,I think your symptoms are problem connection B0 or other ( connections are sometime wrong ) and you need to initialize Bms board by charger…check battery connection .


  28. Hello to everyone! I’m looking fot U4 or U5 (marked L04A) from the BMS board. I cannot find what it is. I found several coincidences but any viable result. Does anyone knows what it does and where could I find it? Thank you in advance for your help.


    1. Antonio, these 8 pin integrated circuits are triple inverters. The full part number is HD74LV2G04A and if you look on the Hitachi Semiconductors website, you will see that they are marked L04A. They are available through distributors such as electrocomponents.


      1. Hi Peter! Thank you for your quick reply! I’ll try to find them. The problem was that as I found this together among others, I was not sure this was the good one. Have anyone solved this problem by changing them?


      2. Basically they say that U4 and U5 are personalised IC’s that you cannot find anywhere, so sadly today we cannot do much about it.


      3. For the sake of completeness, the microprocessor chip is STM8L151K6 but it would require extreme skill to replace this or the BQ76930 BMS chip and both have been customized so only one removed from another BMS board would have any chance of working.

        Antonio, remind me what your problem is that makes you think that U4 and/or U5 need replacing. Are they getting very hot? Or are they damaged?


      4. Thank you Peter again for your quick reply! I had no problem disoldering BQ76930 BMS IC, I did this because 3 or 4 pins where shorted. Those pins are connected to some capacitors and also the cells. Once the IC was removed I found that the pins where still shorted, so I kept on looking for the faulti component untill I found that U4 was also shorted, I found that basically because U5 was not shorted. I cannot tell you the exact pins because right now I do not have the board with my. This is how I found that I should try to replace U4.


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