Dead cell sample lines on JKBMS JK-B2A24S JK-BMS >> FIXED

[kommando]

See post 13 for the pic, for some reason my type of board has 2 P8 pins and tracks, most only have one resistor fitted but both mine were populated so I had a spare. I have now bought some resistors in case more go but there were no 1/16W 0.01 Ω resistors around so I bought 1/8W 0.02 Ω resistors.

As for tools I used a normal soldering iron with a bent thin tip and a LCD microscope.

https://www.aliexpress.com/item/1005005609241325.html?spm=a2g0o.order_list.order_list_main.5.65f31802MT490z

I find as long as you can see close enough then the size of the tools is less important.

Can't advise on where you get a resistor, if it was me and I was sure not to increase the cells then 24 sounds a good resistor to use. Using 18 risks messing up 17.

 

[keepsake]

Would anyone consider this surface mount fuse to be a bad design ? When a fuse pops are you really gonna ship it back to China for repair ?

 

[keepsake]

Hmm -- overlooked the obvious ...
I can put an inline fuse in the external red wire(s) on the cell(s) that I had to jumper in the black box.
I'm thinking the glass tube type AGC 2.5 or 3 amp
I can only imagine how many of these 'blown fuse' BMS units are piling up and getting tossed out !! Over a 5 cent part. Good design China.

 

[keepsake]

100% repaired. Thank you so much, kommando.

 

[keepsake]

This thread has been INVALUABLE in fixing my JKBMS unit.
For anyone with a failed unit, THIS IS A MUST READ.

 

[kommando]

They really should have used these

Surface Mount PTCs - PolySwitch - Resettable PTCs - Littelfuse

www.littelfuse.com

So if say cell V for 3 and 4 went missing and then reappeared after a reset of the BMS you could trouble shoot tracks 3 and 4.

But adding fuses in the feed wires would still be more practical with the disadvantage of extra joints that could go wrong.

 

[OffGridForGood]

This thread has been INVALUABLE in fixing my JKBMS unit.
For anyone with a failed unit, THIS IS A MUST READ.

Go back and Edit the Thread Title to include "Solved" or "Fixed" for future searches

 

[kommando]

And here is the original post by @upnorthandpersonal that provided me with the fix that I copied.

JK BMS Cell Count Problem on B2A24S20P

Yes, I am using the same harness. I will order or make a new one to check that, but the third BMS is working fine on that same harness. do you use fuses on each balance lead coming from the BMS to each cell?

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