Did i Damage My 12V 100A JBD BMS (SP04S034)?

[Wjm1964]

Hi, Hoping someone can shed some light on a weird issue I have with my JBD SP04S034 100A BMS.
It was my understanding that these BMS units could be used in series, however i haven't found any specific information that says what the voltage limits are for these units e.g 24V or 48V
So i have 4 x 12.8V lifepo4 batteries, each battery uses this specific BMS unit and i put them in series to make a 48V battery to use my inverter. Everything worked fine for a while until the inverter stopped operating as normal.

Checking each battery with a multi-meter I found one reading 10.1V across the terminals, yet the APP is showing voltage above 13V? So i checked voltage of the actual cells and it matches the App. So thinking it was perhaps a bad balance lead i checked every connection and all is good. I disconnected the balance leads from the BMS and also confirmed cell voltages at the plug, all good. Now when i re-connected the balance leads the voltage across the main terminals returned to normal for a couple of minutes before dropping back to 10V. If i attach a charger, nothing happens and with the charger connected the voltage reads zero. So seems the BMS has closed the charge FETS?

The highest discharge when batteries where in series was 59.3 Amps (DC)

So have i just been unlucky or are these BMS units unsuitable for a 48V system?

Thanks for reading and i welcome your opinions and thoughts on this.

 

[kommando]

Its a 12V BMS

JBD 4S 12V Lifepo4 BMS 100A 150A 200A Bms Connection With Bluetooth Temp Sensor | eBay

JBD 4S 12V Lifepo4 BMS 100A 150A 200A Smart Bms Series Connection With Free Bluetooth Temp Sensor Lithium Battery H Heating. JBD Smart BMS - SP04S034(New Version). â 4S BMS for 3.2V Lifepo4 battery. Bluetooth link for Phone-Xiaoxiang BMS.

www.ebay.co.uk

From the listing

JBD Smart BMS - SP04S034(New Version)
● 4S BMS for 3.2V Lifepo4 battery

● Continuous Current 100-200A / Balance Current 50-150mA

● Size 192±2*105±0.5*20±1 mm

● Doesn't Support Series Connection

 

[Wjm1964]

Its a 12V BMS

JBD 4S 12V Lifepo4 BMS 100A 150A 200A Bms Connection With Bluetooth Temp Sensor | eBay

JBD 4S 12V Lifepo4 BMS 100A 150A 200A Smart Bms Series Connection With Free Bluetooth Temp Sensor Lithium Battery H Heating. JBD Smart BMS - SP04S034(New Version). â 4S BMS for 3.2V Lifepo4 battery. Bluetooth link for Phone-Xiaoxiang BMS.

www.ebay.co.uk

From the listing

JBD Smart BMS - SP04S034(New Version)
● 4S BMS for 3.2V Lifepo4 battery

● Continuous Current 100-200A / Balance Current 50-150mA

● Size 192±2*105±0.5*20±1 mm

● Doesn't Support Series Connection

Thanks, but their listing says "Series Connection" and i have seen other batteries that use this unit and they also say they can be put in series.

 

[TomC4306]

Thanks, but their listing says "Series Connection" and i have seen other batteries that use this unit and they also say they can be put in series.

You should look again...
Doesn't means does NOT...

 

[Wjm1964]

You should look again...
Doesn't means does NOT...

Thanks, first I've seen that.

 

[kommando]

Ask the manufacturers support

Contact Information

Protection during charging and discharging with additional functions to lengthen battery lifetime, favorable and reliable Battery Management Systems for Electric Vehicle & Inverter& Storage. 10 years BMS manufaturer and supplier, and free shipping and favorable cost for lithium smart and normal...

jiabaidabms.com

 

[Wjm1964]

Ask the manufacturers support

Contact Information

Protection during charging and discharging with additional functions to lengthen battery lifetime, favorable and reliable Battery Management Systems for Electric Vehicle & Inverter& Storage. 10 years BMS manufaturer and supplier, and free shipping and favorable cost for lithium smart and normal...

jiabaidabms.com

Thank you

 

[Wjm1964]

So i have not heard back from JBD but their AliExpress listing clearly says they are -
JBD Smart BMS - SP04S034 (Support Series Connection)

● 4S BMS for 3.2V Lifepo4 battery
● Continuous Current 100-200A / Balance Current 50-150mA

I am totally confused?​

 

[mikefitz]

these BMS units unsuitable for a 48V system?

Since you are in the UK contact Fogstar, they supply similar BMS.

BMS (Battery Management System) l Fogstar UK

Stocking JBD and Daly BMS 12V (4S) 100A - 300A. All BMS in the Fogstar range have been selected to work perfectly with 3.2V LiFePO4 Lithium Prismatic Cells. All of our BMS are stocked in our UK warehouse for FAST shipping.

www.fogstar.co.uk

Since you have seperate 12v batteries each with a BMS, an option would be to rebuild as a 48 volt battery and use a 16s BMS.
This will be a better long term option than having batteries in series .

JBD BMS for LiFePO4 (with Bluetooth) - 16S 48V 200A

The JBD 16S 48V 200A BMS offers a powerful LiFePO4 battery management solution, enabling you to manage, optimise and maintain the performance of your lithium cells. UK Stockists. Next Day Delivery.

www.fogstar.co.uk

 

[Wjm1964]

Since you are in the UK contact Fogstar, they supply similar BMS.

BMS (Battery Management System) l Fogstar UK

Stocking JBD and Daly BMS 12V (4S) 100A - 300A. All BMS in the Fogstar range have been selected to work perfectly with 3.2V LiFePO4 Lithium Prismatic Cells. All of our BMS are stocked in our UK warehouse for FAST shipping.

www.fogstar.co.uk

Since you have seperate 12v batteries each with a BMS, an option would be to rebuild as a 48 volt battery and use a 16s BMS.
This will be a better long term option than having batteries in series .

JBD BMS for LiFePO4 (with Bluetooth) - 16S 48V 200A

The JBD 16S 48V 200A BMS offers a powerful LiFePO4 battery management solution, enabling you to manage, optimise and maintain the performance of your lithium cells. UK Stockists. Next Day Delivery.

www.fogstar.co.uk

So JBD replied and state that the version i have is suitable for series connections - So hope this helps others, if it has 4S on the label it is suitable for series connection. However, i still do not know why mine failed.

 

[justgary]

So JBD replied and state that the version i have is suitable for series connections - So hope this helps others, if it has 4S on the label it is suitable for series connection. However, i still do not know why mine failed.

It seems that you may be a victim of translation to and from Chinese. The BMS is made for series connection of four cells (a 4S battery). It should also not blow up if you put several of those batteries in series. The thing it won't do is balance the charging or discharging among the various 4S batteries. You could add a 12V 4S balancer to see if you get better performance.

When you assembled the battery, did you top balance all of the cells, and then the four 4S batteries before you put it in service?

 

[Wjm1964]

It seems that you may be a victim of translation to and from Chinese. The BMS is made for series connection of four cells (a 4S battery). It should also not blow up if you put several of those batteries in series. The thing it won't do is balance the charging or discharging among the various 4S batteries. You could add a 12V 4S balancer to see if you get better performance.

When you assembled the battery, did you top balance all of the cells, and then the four 4S batteries before you put it in service?

Yes I believe I did everything to the letter. Now my confusion is with how to determine if the Mosfets on a BMS suitable for series connection are only good for 24V set ups instead of a 48V system. It seems difficult to get any information on mosfet voltage types and limits. There are so many lifepo4 batteries stating you can connect 4 in series but how true are these statements. I've been trying to find data on the mosfets used on the jbd to better understand what voltages they are rated for.

 

[TomC4306]

I've been trying to find data on the mosfets used on the jbd to better understand what voltages they are rated for.

Remove the heatsink from one side and wipe the thermal paste off a MOSFET.
Part number printed on there
Web search for spec sheet.

 

[justgary]

I don't see how building batteries with series connections of smaller batteries will cause a problem with voltage in any one BMS if the wiring is correct. The transistors only care about the voltage they see relative to their reference, which should be the "negative" pole of that particular BMS. The BMS should not care if it has a DC bias applied that lifts its voltage based on some other reference, e.g. the "negative" pole of the first BMS in the string. Any one BMS knows nothing of that bias voltage.

By the way, which BMS in the string failed?

Maybe you did get unlucky. I like the idea of reading the part number from the transistors, and possibly replacing them with new ones to see if it comes back to life.

 

[Wjm1964]

I don't see how building batteries with series connections of smaller batteries will cause a problem with voltage in any one BMS if the wiring is correct. The transistors only care about the voltage they see relative to their reference, which should be the "negative" pole of that particular BMS. The BMS should not care if it has a DC bias applied that lifts its voltage based on some other reference, e.g. the "negative" pole of the first BMS in the string. Any one BMS knows nothing of that bias voltage.

By the way, which BMS in the string failed?

Maybe you did get unlucky. I like the idea of reading the part number from the transistors, and possibly replacing them with new ones to see if it comes back to life.

By the way, which BMS in the string failed

The main positive battery from the 4 in series. The main negative and the other 2 batteries were unaffected. As I know the max amps I pulled couldn't be to blame, I wondered if it just didn't like 48V hence trying to educate myself a bit more about transistors and mosfets.