8.3. BMS issues. Victron energy Lithium Battery Smart

Lithium Battery Smart Manual

• How deep has the battery been discharged on average? The battery will last for less cycles if deeply discharged, compared to more cycles if discharged less deep.

• For more info on the life cycle see chapter: Technical data”.

To check if the battery has been misused:

• Is the BMS connected and functional? Not using the battery with a Victron Energy approved BMS voids the warranty.

• Is there mechanical damage to the battery, its terminals or the BMS cables. Mechanical damage voids the warranty.

• Has the battery been mounted upright? The battery can only be used in an upright position.

• Check the “allowed to charge minimum temperature” setting in VictronConnect? Also check if the battery temperature offset has not been set to an unrealistic value. Charging the battery below 5°C voids the warranty.

• Is the battery wet? The battery is not waterproof and is not suitable for outdoor use.

• Is there an indication that the battery bas been totally discharged? Look at the battery monitor settings or VRM. Inspect the deepest discharge, minimum battery voltage and number of full discharge in the battery monitor. Total and very deep discharge voids the warranty.

• Is there an indication the battery has been charged with too high voltage? check the maximum battery voltage and the high voltage alarms in the battery monitor.

8.3. BMS issues

8.3.1. The BMS frequently disables the battery charger

A well-balanced battery does not disable the charger, even when the batteries are fully charged. But when the BMS frequently disables the charger, this is an indication of cell imbalance.

In case of moderate or large cell imbalance it is an expected behaviour that BMS frequently disables the battery charger. This is the mechanism behind this behaviour:

As soon as one cell reaches 3.75V the BMS disables the charger. Whilst the charger is disabled the cell balancing process still continues, moving energy from the highest cell into adjacent cells. The highest cell voltage will drop, and once it has fallen below

3.6V the charger will be enabled again. This cycling typically takes between one and three minutes. The voltage of the highest cell will rise again quickly (this can be in a matter of seconds) after which, the charger will be disabled again, and so forth. This does not indicate a problem with the battery or the cells. It will continue with this behaviour until all cells are fully charged and balanced. This process might take several hours. It depends on the level of imbalance. In case of serious imbalance this process can take up to 12 hours. Balancing will continue throughout this process and balancing even takes place when the charger is disabled. The continued enabling and disabling of the charger can appear strange but rest assured that there is no problem. The

BMS is merely protecting the cells from over voltage.

8.3.2. The BMS is prematurely turning chargers off

This could be because of a cell imbalance. One cell in the battery has a cell voltage above 3.75V. Check the cell voltages of all the batteries that are connected to the BMS.

8.3.3. The BMS is prematurely turning loads off

This could be because of a cell imbalance.

If a cell has a cell voltage below the "Allowed to Discharge" setting in the battery the BMS will turn the load off. The "Allowed to

Discharge" level can be set between 2.6V and 2.8V. The default is 2.8V.

Check the cell voltages of all the batteries that are connected to the BMS using the VictronConnect app. Also check if all batteries have the same "Allowed to Discharge" settings.

Once the loads have been turned off due to low cell voltage, the cell voltage of all cells needs to be 3.2V or higher before the

BMS will turn the loads back on.

8.3.4. The pre-alarm setting is missing in VictronConnect

Pre-alarm is only available if the battery supports it. The current battery models all support it, but older batteries do not have the hardware necessary for the pre-alarm feature.

8.3.5. BMS is displaying alarm while all cell voltages are within range

A possible cause is a loose or damaged BMS cable or connector. Check all BMS cables and their connections.

First rule out that the cell voltages and temperature of all connected batteries are in range. If they are all in range, then follow one of the following procedures.

Also consider that once there has been a cell under voltage alarm, the cell voltage of all cells need to be increased to 3.2V before the battery clears the under voltage alarm.

A way to rule out if a fault is originating from a faulty BMS or from a faulty battery, is to check the BMS using one of the following

BMS test procedures:

Single battery and BMS check:

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