NG Batteries, BMS & smart shunt

Q&A and troubleshooting DESS
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1

Subject: Incorrect BMS & SmartShunt Supplied for Victron Lithium NG Batteries

Hi All,

I’m writing regarding the Victron components supplied for my 24 V lithium system, specifically the BMS and monitoring equipment.

After reviewing Victron’s official documentation for the batteries supplied, I believe there has been a mistake in the BMS selection.

Batteries supplied

•	**Victron Lithium NG 25.6 V 200 Ah**

Part number: BAT524120610 (x2)

BMS supplied

•	**SmallBMS**

Part number: BMS400100000

Battery monitor supplied

•	**SmartShunt 500 A**

Part number: SHU065150050

Issue identified

According to Victron Energy’s official documentation:

1\. **Victron Lithium NG batteries require a Lynx Smart BMS NG**

Victron states that the Lynx Smart BMS NG is mandatory and must be purchased separately for Lithium NG batteries.

The SmallBMS is not suitable for Lithium NG batteries used in inverter/charger systems.

2\. **The supplied SmallBMS is not compatible with my system**

My system includes:

•	MultiPlus-II 24/5000 inverter/charger

•	SmartSolar MPPT

•	DC-DC chargers

•	GX system (Cerbo GX)

Victron specifies that Lithium NG batteries in inverter-based systems must use a Lynx Smart BMS NG, which provides:

•	High-current contactor

•	Charge and load disconnect

•	CAN-bus communication

•	Full integration with GX devices

3\. **The SmartShunt is not required when using a Lynx Smart BMS NG**

The Lynx Smart BMS NG already provides:

•	Current measurement

•	State of charge (SOC)

•	Battery protection

•	Communication to Cerbo GX via CAN

In Victron’s recommended Lithium NG system designs, a SmartShunt is not used alongside a Lynx Smart BMS NG, as it becomes redundant and can cause duplicated or conflicting measurements.

Based on the above, I believe the correct configuration for my system should be a Lynx Smart BMS NG (500 A or 1000 A as appropriate) but before I bring this up with my supplier I would like some confirmation on my findings.

I look forward to hearing from anyone who has knowledge on the subject!

Stanley

2

There is a SmallBMS NG which is compatible with the Lithium NG batteries, but the old SmallBMS is not compatible, as that’s for the Lithium Smart batteries, not the Lithium NG batteries.

A Lynx Smart BMS NG is not required for your system; a VE.Bus BMS NG would also work, and it would be between you and your systems designer/installer to discuss the pros and cons of various setups, but regardless, the SmallBMS -if indeed it’s not the NG version- is the wrong BMS entirely for those batteries.

3

Hi Justin,
Thanks for getting back to me, I will look into the smallBMS NG. If I was to run with the smallBMS NG I take it I would still need a smart shunt, however if I went with the Lynx NG I would not require one. Is this correct.
Thanks for the help.
Stanley

4

Yes, any system other than the Lynx Smart BMS NG should use a SmartShunt or BMV-712. If it was me, since you have a VE.Bus device on the system, I wouldn’t advise looking at the SmallBMS NG even though it could be made to work; rather, look at the VE.Bus BMS NG or the Lynx Smart BMS NG, either way. Again, discuss with your system designer/installer to work out what will make the most sense for your system; just ensure that whatever BMS you decide on, it’s an NG BMS since that is required for NG batteries.

5

Thanks Justin!!

6

Justin,

In regards to the NG batteries, are they the same as the Smart A batteries?

Thanks, Stanley

7

They are not; the NG battery line is a completely different line than the Smart and Smart-A lines, thus the requirement for different BMSs!