BMS questions - Leaf pack

[jeffro22]

Finally made the switch from my failed chargery BMS setup to the generic bluetooth chinese BMS.

Have several questions

I know this was not ideal but for almost a year now I haven't had a BMS. Now that I have it hooked up it appears one cell is out of balance. What are my options with this?

Are there any setting inside the APP that need to be adjusted ?

Are the 2 small temp sensor leads normally run to the pack? Mine dont seem long enough based on where i mount my BMS

My chargery setup used a shunt which is still installed, but the small leads aren't hooked to anything now. Do I just leave it as-is or should I remove?

[augiedoggy]

Originally Posted by jeffro22

Finally made the switch from my failed chargery BMS setup to the generic bluetooth chinese BMS.

Have several questions

I know this was not ideal but for almost a year now I haven't had a BMS. Now that I have it hooked up it appears one cell is out of balance. What are my options with this?

Are there any setting inside the APP that need to be adjusted ?

Are the 2 small temp sensor leads normally run to the pack? Mine dont seem long enough based on where i mount my BMS

My chargery setup used a shunt which is still installed, but the small leads aren't hooked to anything now. Do I just leave it as-is or should I remove?

Ive never heard of a generic chinese bms... No idea which one it is or what app your running. Could you post a link? The chinese made bms I have are made by jbd and ANT.. you may have enough built in balancing capability to correct it or you may not..you could manually discharge that one cell with a 5v load..

On the flip side it the chargery bms the blue ones with the separate blue box touchscreen? If so I see those for sale out of china still on aliexpress and I believe they were made there all along...
https://www.aliexpress.com/i/3256802...apt=4itemAdapt

[Volt_Ampere]

If that cell is really that high (check with an accurate DVM) then you should discharge it down to the others manually. I would use a 12V halogen bulb or something similar connected to just that cell until it's down with the rest of them. It will take forever for most Balancing circuits to balance a cell that is that far out.

[jeffro22]

Thanks. Will plan to drain that battery with a Light

This is the bms that Sergio and pingeye have used

[Pat911]

So it’s a JBD. Nothing wrong with those.

[jeffro22]

Originally Posted by Volt_Ampere

If that cell is really that high (check with an accurate DVM) then you should discharge it down to the others manually. I would use a 12V halogen bulb or something similar connected to just that cell until it's down with the rest of them. It will take forever for most Balancing circuits to balance a cell that is that far out.

I am assuming i need to disconnect the busbars from the pack in order to isolate this cell in order to test and drain , correct?

[Volt_Ampere]

Nope. Just connect a load to the high cell. No reason to disconnect things. Just make sure you monitor the voltage on that cell so that you don't discharge it too far.

[jeffro22]

I just checked everything with a DVM and all the cells are reading between 4.00 -4.03

I have a total of 14 leaf batteries, so my pack is 7 sets of 2 batteries paired together.


SO maybe i am getting a bad reading form BMS. Anything to try and reset or adjust settings? Or do I likely have a faulty unit?

I suppose I could swap the taps from 13 and 14 and see if the reading follows?

[georgia088]

Originally Posted by jeffro22

I just checked everything with a DVM and all the cells are reading between 4.00 -4.03

I have a total of 14 leaf batteries, so my pack is 7 sets of 2 batteries paired together.


SO maybe i am getting a bad reading form BMS. Anything to try and reset or adjust settings? Or do I likely have a faulty unit?

I suppose I could swap the taps from 13 and 14 and see if the reading follows?

I would check the connection of your "sense" wire good on that cell. When I connected mine up, one cell read low and when I tightened it up good the voltage read like the others. I assume by tightening it up, I reduced the resistance.

[Pat911]

I suppose I could swap the taps from 13 and 14 and see if the reading follows?

You cannot just swap the taps, BMS’s don’t work like that. They need to sense each battery in the order they are connected. You can actually damage the BMS by doing so. You would need to swap the leaf modules.

Start by checking all wiring as already suggested. The fact that it’s cell 14, the last cell, could be significant and indicate a faulty BMS.