JBD BMS incorrect voltage readings

[neil_99]

I have 4 - JBD 100Amp BMS all wired up in the same way and in parallel. However, one of my BMS reads the voltage on terminals 1 & 2 incorrectly (See attached screenshot). I have checked the voltage on the terminals, and they are all approximately the same (around 3.29v). I also disconnected the plug from the BMS and verified that I get the same voltages (all approximately 3.29v) at the plug. I believe my BMS is faulty. Is there something I could be missing other than the BMS which could be the cause of this error? I did check the wiring and this battery is wired the same as all my other batteries (which don't have this problem). I've also double-checked and all of my terminals are tight. But I would think that if my problem is with either of those (incorrect lead placement or loose terminals) I wouldn't be getting the same voltage on all of the plug terminals.

 

[MisterSandals]

Have you tried one of the other BMSs on this battery?
Happen to have a pic of the battery and wiring? Sometimes extra eyes find things.

 

[Bob B]

Have you tried one of the other BMSs on this battery?
Happen to have a pic of the battery and wiring? Sometimes extra eyes find things.

That's what I'd do first.

 

[WingNut]

JBD BMS voltage readings can be calibrated using JBDTools with UART box & Windows PC and maybe also with the IOS app (not 100% sure on that).

 

[HRTKD]

Half the voltage problems reported on the forum are due to bad connections. A picture would help. One bad bus bar, ring terminal, wire, oxidized surface could be the culprit.

As suggested by Bob, swap the BMS out with another one, using the same balance wires that are already in place. If you see the same voltage issue then the balance wire or balance wire connector could be the issue, assuming you've verified everything else at the cell terminal is solid.

 

[neil_99]

I'll swap out the bms tonight and work on getting some pictures. Thanks for your help!

 

[neil_99]

Okay, when I swap the BMS, I get the different voltages, so it must be my wiring. Here are some pictures.

 

[neil_99]

I think I found the problem. One of the little crimps was flaky. Sometimes it tested as a complete circuit and sometimes it didn't.

 

[neil_99]

Yep, that appears to have fixed it. I'll check again tomorrow morning, but everything was even a few minutes ago.

 

[Nivya]

Hello, I have a similar problem. I have a JDB 14S 200A BMS. I followed wiring in I found in one of JDB pdfs on this site. The values of 1st and 2nd cell voltages were faulty in the app. So I connected the BMS to PC and tried calibrating it. I'm using the app I found in Desktop_App_Overkill. I could calibrate the 2nd cell voltage but I cannot do it for the first cell. It shows that the calibration is successful but that does not solve the problem. I checked my crimps, wiring, the cell voltages of the pack, changed the pack but nothing helps. This pack worked for other QUCC BMS but I'm not sure what's wrong here. Did I miss checking something?

 

[neil_99]

Every time I've had his problem, I eventually found a bad crimp on the little balance cables.

 

[Nivya]

Every time I've had his problem, I eventually found a bad crimp on the little balance cables.

I made 2 harness, and it still shows the same problem. Checked the continuity and resistance for all the terminals and that looks good too.