@ando Hi there! I had to replace that same capacitor. it is a 1uF 2012 package and I used a 10V rating. You can buy them in Newark

https://www.newark.com/kemet/c0805c105k8ractu/ceramic-capacitor-1uf-10v-x7r/dp/64K2894?st=2012 1f capacitor 10v

Hi all! I´m new to this forum and new to the onewheel world! I just got a faulty XR (very bad condition) and I´m trying to resurrect it... which looks challenging at this point. I saw that there is a high level of tech knowledge here, so I wanted to see if you could help me on this:

HW: 4212 (lucky me)
SYMPTOMS: Error 16; battery not charging.
FIRST GUESS: BMS fried

Upon opening up the battery box, I see C11 missing, which is a 1uF capacitor. I also assume that the voltage should be for the cell, which should be 4.5V (I saw on other designs that the voltage covers the total voltage of the entire battery pack -63V-). If my assumption is correct, I would go for a 1uF 10V ceramic capacitor.
I checked RS-485 comms. Resistance appears to be OK (121 ohm between terminals). However there is continuity between terminal 5 (GND) and 8 (Vcc) in the SN65HVD1786. Looks like it is fried and has to be replaced. C33 it is also shorted and has to be replaced (100 nF - 220 nF 6V ceramic capacitor)
I also checked the PIC to see the status of it, since it is the driver of the comms. Terminals 16 (Vss) and 17 (Vdd) are shorted. BUT I didn´t check yet if it is due to the capacitors installed between these pins (C34 and C35 which I honestly don´t know the value) OR to a short on the PIC internals. If I decide to replace the PIC I would have to program it with a firmware... which I do not have. Those capacitors are installed between Vdd and Vss. Difficult to see the traces, but I assume it by the position and continuity.
On the controller side, SN65HVD1786 is good and R=121 Ohm (at least something good). I assume the controller side is OK.

So at this point I don´t know how far should I go with this because I have some limitations (never soldered SMD, BMS PIC Firmware missing). I have some questions to see if you could give me a hand...

1.- Does anybody know if the firmware for BMS 2110 pcb is available? or any custom firmware to flash? (I can program PICs, that should not be a problem, but I do not have any .hex)
2.- Has anybody tried to flash the PIC of a 4212 BMS with an older BMS PCB? (i.e. 4209)
3.- (this is the tough one) Does anybody know the value of the C34 and C35 capacitors? Are installed between Vss and Vdd of the BMS PIC ucontroller, and are REALLY tiny. I cannot find information about them.

Besides that, the XR has most of the screws missing, no bumpers or fender. I guess I will spend some time on this one...

Thank you guys!!!

Replaced max ic, installed missing capacitor. E16 is gone! Which means that max ic and pic are supposed to be ok.
However, the OW only stays on when plugged. As soon as i unplug the charger it turns off. I see that the area on the top of the balancing connector gets hot, but that’s a bunch of resistors mostly…

I saw some questions in regards with how to identify the part when working with SMD components. Yes, it´s a pain in the neck; manufacturers do not have space enough for all the letters/numbers on the part itself, so they put a very "random" reference and we just deal with it.

No worries, everything has a solution except death (as of today). To identify the SMD part just follow the next steps:

1.- Identify the SMD component that is faulty.
2.- Identify the reference on the silk screen.
3.- Grab a cold can of your favourite soda/beer.
4.- Identify the package the component has (SOT-XXX). This could help: https://en.wikipedia.org/wiki/Small-outline_transistor
5.- Now go to https://smd.yooneed.one/
6.- Click on the button with the same two first digits of the reference identified in (2)
7.- Search for the entire reference on the list. It will most likely have several options for the same reference. Here is when you have to use the information of (4), since there are not many options for the same package.
8.- Once identified, just drink the can you got in (3).
9.- (OPTIONAL) put on your shades. Now you will feel cool AF; you cracked the code xDDDD.

EDIT: SIZES
When searching for replacements, it is important to take into account the size of the component since one component for an specific value con be manufactured in different sizes (i.e. capacitors).

This chart can be handy:

https://www.topline.tv/sizechart.html

I know that we will see exceptions (everything has at least one exception), but it is a good start. I hope it helps!!!

@lia thank! Well, for the cells voltage… didn’t measure -_-u. It was only to see the voltage for the capacitor; somewhere bigger than 4.5 should be fine.

To be honest… i don’t know what happened to this board, the previous owner opened it and i don’t know what was done… but it’s a disaster. After all these issues i was expecting a “lucifer was here” on the back of the board. Once i arrive home i will take a picture of the board. I think that if this bms pcb is the same as an older one i could get the fw and flash it. But, as you say (and nkotb knew) step by step. I’ll start with the rs-485 replacement and i will also desolder the capacitors to see if it is on the pic or not.

@sirgu thank you! I hope so… it is my opportunity to finally have my one wheel! Hahaha

bms 2110 here is the bms board. For the record xd

@lemur i hve a couple of pics in my cart already hehehe. But now the question would be if i can install a new pic (flashed with an old firmware revision) and would work (+owie). I would say that the hardware at logic level is the same (but i do not have a board to compare). If this is the case i can search for a 4209 firmwware and test. The bms is already out, soooo i guess there is nothing to lose xD

@lemur i can see them on the link. Does it guve you any kind of error?

Ok, some news:
C33, c34 and c35 are ok. Removed from the pcb to try to isolate the short with no luck (at least i measured the cap values).
I desoldered gnd from the 1786 and looks like that this one is not shorted either. I still have a short between gnd and vcc, so either the pic is shorted or i think i should go to the voltage regulator (which i have to look for on the power area). This sounds promising… (i’m starting to lose faith…)

Fixed the hot point. As i was expecting, that issue had no relation with the no-power issue. I measured V on the big mosfets next to the batt connectors. There is no V. However, i have V on the other smaller ones. I’m thinking that maybe they are not receiving anything on the gate terminal. I followed the gate track and looks like that are going to those sOT-23 thingies which i guess are transistors. Looks like those are OK but i do not know who is sending the triggering/gate signal. Do you guys have any guess/recommendation?

@lia yes, but it doesn’t turn on. I also cheched the button just in case and works. One thing i want to check though is if the switch signal reaches the bms.. but i jumped the wires and nothing happened ;,(

@lemur and did that issue make the OW to be dead or was just a diagnostics issue (voltage not showing ok)?

@lia yep, I found the MAX chip getting hot and I replaced it. Then the hot point went from there to Q4 (one of the m8t mosfets). replaced and shorted again. On this one i found the issue (short between the terminals of one of the sample capacitors to read V on cells). But besides this... I really don´t think that a short in the sampling reading of the cells can make the OW to be dead, right? I mean, the only thing i can think of is that the MAX is getting crazy and is sending bollocks to the PIC. the PIC is also getting bollocks with that info and I guess the controller interprets tht something is wrong. But i don´t think this design is that complex.

The summary of the current status is the same: if i plug it in it works (and voltage is at 100% -weird-) and I do not get any error, but if it is not plugged...dead. Should be something related to the power section of the BMS but I don´t know where to look besides the MOSFETS. everything looks good!

One cell was bad. Replaced it- i now have V output-. The OW still does not power on and still have a hot point. I’m trying to deal with the hot point to see which component is the culprit (this hot point is in one of the MOSFETs -Q4- on the cell balancing-sampling area of the BMS). I think though that this mosfet issue has nothing to do with the no power issue.

Ok guys, i really need your knowledge on this because i do not really have an explanation for the following:

I found out that the battery is giving me 0volt between terminals. I measured all the cells (15 cells) and every one of them is fine… except the last one. But here is the plot twist:
*Each cell (cells 1-14) voltage is 3,6-4 volts between cell - and cell +. Good so far
*The last cell (cell 15) is 0 volts between cell - and cell +
*If i measure between battery negative terminal and cell 14 positive terminal i get 52 volts. Taking into account that i think that this is not charging… i guess that this is fine; voltages are lower when discharged.
*If i measure between last cell positive terminal and battery negative i get 0 volts.

So the last cell is acting as an open circuit and that is why i’m not getting voltage on the battery terminals. I guess is not charging for the same reason.

Obviously the cell is bad, but i do not know enough about batteries to explain why the cell behaves as an open circuit. Anyone knows? I thought that if the cell is bad it behaves as a short.

@ando Hi there! I had to replace that same capacitor. it is a 1uF 2012 package and I used a 10V rating. You can buy them in Newark

https://www.newark.com/kemet/c0805c105k8ractu/ceramic-capacitor-1uf-10v-x7r/dp/64K2894?st=2012 1f capacitor 10v

@lemur any recommendations? I saw the mg chemicals but it is low temp. The chipquick looks good (with lead)

Guys… do you recommend solder paste for the big pad of the mosfet? I saw that the melting temp of the solder paste is 183C (361F), which i think is safe enough, but maybe those mosfet get really hot on normal conditions and i don’t want to screw it up

@loaffette LOL
I thought on the wire but then i remembered all the problems i had in the past with vibrations on things that move and i will try to repair the pad with epoxy and copper. If it doesn’t move i don’t have to worry. On motherboards that are usually static there is no problem, but i’ve seen broken cables just due to vibrations, which is a pain