in the stationary battery i am using cabling recycled from ethernet cable unshielded. my battery is about 342v (85s actually) , maximum of 15A but normally with very low amps so no problem with EMI.
in the car, still in construction and never run more than 200m around my home, have shielded ethernet ...

I am just follow the logic.
As you say if that happen in your bench with only one BMS12 , but also with other different BMS12 alone, look that the problem can be with the EVMS brain or the display.
I dont think software is the cause, because i have the same software working correctly.

the total voltage shown in the screen is the summatory of all the cells calculated individually.
So, what I would try is to isolate which bms slave is provoking this flicking voltage reading. Mounting each cell block and testing when appear the flicking.
If I had to bet, I would say that it is ...

running state is when 12v are applied to "key in" in EVMS3. (Just for info: Balancing cells is only done when evms3 is in running state.)
no 12v on "key in" automatically changes to Idle.
Alternating running/idle is strange. Can you inspect this before to revise why 123v are displayed.

if you dont want to modify firmware or do a new compile You can modify hardware. See the lines 32 and 224 in the code:

#define SELECTOR1 (!(PIND & (1<<PD3)))
#define SELECTOR2 (!(PIND & (1<<PD2)))
#define SELECTOR3 (!(PIND & (1<<PD4)))
...
// Selector 2 and 1 used for current size.. 00 means 100A ...

#define SHUNT_VERSION 0 // for hall sensor
#define HALL_MULTIPLIER 1L // for 300A

with jlcpcb i order to mount the resistors, capacitors, diodes, small parts.
LT chips , adum, atmega, conectors ... I install myself, but advice everyone: LT chips is not easy

I have evaluated in the past whether to make them and the cost was more than half of a BMS24, so I only made BMS24.
user prensel had bms12 units for sale. ask him if he still sells them. If not, come back to me.
I can also instruct you how to make it yourself, basically what you might find difficult ...

i never builI any BMS12s because I never needed them. But I think they would work due to the way they are built.

I found that the open source design for the display (i dont know if the original/commercial design is the same) have a voltage regulator that heat too much, so in my buildings i need to mount a heat disipator over to last. Other option is to feed alone the display with 5.5 or 6v and you will not ...

yes i have it. PM sent

yes i have it.

there are 3 TUV in gottingen... did you check the one in dieselstrabe ?

I have already got my hands on the hantek and have already tried it with DC. Originally the scope has not AC coupling but it can be modified to have it. If I want to test the AC output signal... need to have the AC coupling modification ? where do I put the probe connectors? one goes to L1 but the ...

looks you still did not upload the sketch data.
... - select tools/ESP8266 sketch data upload and wait for the board to reset ...

see here the message from arber:
viewtopic.php?t=8

I cancelled the OWON choice because I found also linux software for the hantek scope,
also because Owon was a bit short of memory (5k) vs hantek (1M)
, so I take the 6022BL
here is the linux software: https://github.com/OpenHantek/OpenHantek6022

thanks all for the suggestions.

was ready to buy the hantek but I found linux software for this: github.com/florentbr/OWON-VDS1022
So the OWON VDS1022I is my choice.

thanks for all your advice.

i am considering the hantek 6022BL = 2 channels + 16 Channels Logic Analyzer
i dont know how important are the 16 channels. Can be nice to have it ?
I see it can use the saleae software :

like owon with the protected usb... i can remember johu burnt a oscilloscope because unprotected usb. If this happens to the master ...
The 4 channels version from owon goes to 750 euros
2 channels owon suggested by uhi is 86 eu.
aliexpress suggest me hantek brand but for about the double of owon ...

I forgot to say something... if the oscilloscope is USB, I prefer one that supports Linux, even if it is through virtualbox

My terios is collecting dust in the garage and the time has come to have a tool to help me diagnose what is wrong with my inverter.
I ask you for help in choosing an oscilloscope that meets what is needed in an EV conversion as cheaply as possible. I don't care if I have to connect it to a laptop. I ...

this story starts here:
viewtopic.php?p=65152#p65152

because nobody has interest to buy, I am asking somebody living near of 02625 Bautzen could pickup a.s.a.p. and store for me till I get a transport for the items.
thanks

yes , 100 kg, over a total of 2260kg permitted.
they saved the world with this action.

today, driving with some items for my ev conversion, polizei stop me and the weight of the car surpasses by 100kg the permited, so they ordered unload 100kg:
rear axle, that is motor + differential + extra couplers . couplers i have not much details, but probably are for soldering. it was a extra i ...