Issue with Lithium NG battery and Lynx Smart BMS NG

Q&A and troubleshooting
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1

Dear all,

I would like to ask you about some issues with our new lithium batteries (NG and NG Smart BMS).

We powered up a new installation using five brand-new Victron LiFePO4 NG batteries (Victron 51.2V/100Ah) connected to a system comprising three Multiplus II 5000 units, a Lynx Distributor and BMS, five VE Lithium 51.2V/100 batteries in parallel, and a Fronius PV inverter.

During charging and nearing full capacity, the BMS shuts off the DC load contactor with the following:

Lynx Smart BMS NG: BMS cable: Alarm

Lynx Smart BMS NG: BMS: Contactor error

Lynx Smart BMS NG Distributor C Fuse 1 Blown…3 Blown

I checked the batteries, and one cell in one battery was around 3.64V, while all the other cells were within the normal range across all batteries.

My question is whether this behavior of the BMS is normal. According to the manual, the BMS will stop the chargers, but there is no mention of a complete disconnect of the rest of the system. If this is the case, how can I balance a single cell in one battery if all the others are around 3.5V and the BMS is disconnecting the chargers via the contactor? Should I leave the system with errors and system will reconnect automatically when the voltage drops below a certain threshold, or do I need to be on-site to manually restart it or remove the battery for investigation or rebalancing?

For now, I have lowered the charging voltage in the DVCC menu to 54.4V and am considering additional steps.

2

Did you perform a slow initial charging before installing the system?

Reduce the current via DVCC, set the system to keep the batteries charged and give the system time to balance.

3

Hi Matthias,
If you mean each battery alone - no.
The manual states that if the batteries are in parallel, there’s no need for an initial charge.
I checked the voltage of all batteries during installation, and they were more or less the same, with a difference of about 0.01 0,02V.
However, I did perform an initial charge on all batteries using a Multiplus 12 kW - 200A charger for 5 batteries (40A each = less than 0,5C). Each battery is connected to the same bus bar, with equal cable lengths(for all terminals), so they should be balanced in terms of cables, etc.
OK you recommend lowering the charging current? If so, what value would you suggest for 5 batteries? Or should I try charging this battery individually.