6. Troubleshooting & support
The first step in troubleshooting should be to follow the steps in this chapter for common battery issues.
If you experience problems with VictronConnect, first consult the VictronConnect manual, especially the troubleshooting chapter.
Should all this fail to resolve the issue, scan through popular questions and answers regarding your product and ask the community of experts in the Victron Community. In case the problem persists, contact the point of purchase for technical support. If the point of purchase is unknown, refer to the Victron Energy Support webpage.
6.1. Battery issues
6.1.1. How to recognise cell imbalance
The BMS frequently disables the charger
This is an indication that the battery is imbalanced. The charger will never be disabled by the BMS if the battery is well-balanced. Even when fully charged, the BMS will leave the charger enabled.
The battery capacity seems to be less than before
If the BMS disables loads much sooner than it used to, even while the overall battery voltage still looks OK, this is an indication that the battery is imbalanced.
There is a noticeable difference between the individual cell voltages during absorption stage
When the charger is in the absorption stage, all cell voltages should be equal and between 3.50V and 3.60V. If this is not the case, this is an indication that the battery is imbalanced.
A cell slowly drops in voltage when the battery is not used
This is not an imbalance, although it might look like it. A typical example is when the battery cells initially all have equal voltages, but after a day or so of not using the battery, one of the cells has dropped 0.1 to 0.2V below the other cells. This cannot be fixed by rebalancing, and the cell is considered to be defective.
6.1.2. Causes for cell imbalance or a variation in cell voltages
The battery has not spent enough time in the absorption charge stage.
This can, for example, happen in a system where there is not enough solar power to fully charge the battery, or in systems where the generator is not running long or often enough. During normal operation of a lithium battery, small differences between cell voltages occur all the time. These are caused by slight differences between the internal resistance and self-discharge rates of each cell. The absorption charge stage fixes these small differences. We recommend a minimum absorption time of 2 hours per month for lightly cycled systems, such as backup or UPS applications and 4 to 8 hours per month for more heavily cycled (off-grid or ESS) systems. This allows the balancer enough time to properly balance the cells.
The battery never reaches the float (or storage) stage.
The float (or storage) stage follows the absorption stage. During this stage, the charge voltage drops to 13.5V (in a 12V system), and the battery can be considered full. If the charger never enters this stage, it might be a sign that the absorption stage has not been completed (see previous point). The charger should be allowed to reach this stage at least once a month. This is also needed for battery monitor SoC (state of charge) synchronisation.
The battery has been discharged too deeply.
During a very deep discharge, one or more cells in the battery can drop well below their low voltage thresholds (2.60V hardcoded). The battery might be recoverable by rebalancing, but there is also a realistic chance that one or more cells are now defective and that rebalancing will not be successful. Consider the cell to be defective. This is not covered by warranty.
The battery is old and is near its maximum cycle life.
When the battery is close to its maximum cycle life, one or more battery cells will start to deteriorate, and the cell voltage will be lower than the other cell voltages. This is not an imbalance, although it might look like it is. This cannot be fixed by rebalancing. Consider the cell defective. This is not covered by warranty.
The battery has a defective battery cell.
A cell can become defective after a very deep discharge when it is at the end of its cycle life or because of a manufacturing fault. A defective cell is not unbalanced (although it might look like it is). It cannot be fixed by rebalancing. Consider the cell defective. Very deep discharge and end-of-cycle life are not covered by warranty.
6.1.3. How to recover an imbalanced battery
Charge the battery using a charger configured for lithium and controlled by the BMS.
Be aware that cell balancing only occurs during the absorption stage. Each time the charger goes to float, it must be manually restarted. Rebalancing can take a long time (up to a few days) and requires many manual charger restarts.
Be aware that it might look like nothing is happening during cell balancing. The cell voltages can remain the same for a long time, and the BMS will repeatedly turn the charger on and off. This is all normal.
Balancing takes place when the charge current is at or above 1.8A or when the BMS has temporarily disabled the charger.
Balancing is almost finished when the charge current drops below 1.5A and the cell voltages are close to 3.55V.
The rebalancing process is complete when the charge current has dropped even further, and all cells are 3.55V.
Warning
Be 100% sure that the BMS controls the charger; dangerous cell overvoltage can occur if it is not. Check this by monitoring the cell voltages using the VictronConnect app. The voltage of the fully charged cells will slowly creep up until 3.7V has been reached. At this point, the BMS will disable the charger and the cell voltages will drop again. This process will continuously repeat until the balance is restored.
Calculation example of time required to restore a heavily imbalanced battery:
Imagine a 12.8V 200Ah battery with one heavily undercharged (discharged) cell for this example.
A 12.8V battery contains 4 cells, each with a nominal voltage of 3.2V. They are connected in series, resulting in 3.2 x 4 = 12.8V. Like the battery, each cell has a capacity of 200Ah.
Let's say the imbalanced cell is only at 50% of its capacity while the other cells are fully charged. To restore the balance, the rebalancing process will need to add 100Ah to that cell.
The balancing current is 1.8A (per battery and all battery sizes, except for the 12.8V/50Ah model, which has a balancing current of 1A). Rebalancing the cell will take at least 100/1.8 = 55 hours.
Balancing only takes place when the charger is in the absorption stage. If a 2-hour lithium charge algorithm is used, the charger will need to be manually restarted 55/2=27 times during the rebalancing process. If the charger is not restarted immediately, the balancing process will be delayed, and this will add to the total balancing time.
Tip
A tip for Victron Energy distributors and professional users: To avoid having to restart the charger continuously, use the following trick. Set the float voltage at 14.2, this will have the same effect as the absorption stage. Also, disable the storage stage and/or set that to 14.2V. Or alternatively, set the absorption time to a very long time. What matters is that the charger maintains a continuous 14.2V charge voltage during the rebalancing process. After the battery has been rebalanced, set the charger back to the normal lithium charge algorithm. Never leave a charger connected like this in a running system. Keeping the battery at such a high voltage will decrease the lifetime of the battery.
6.1.4. Less capacity than expected
If the battery capacity is less than its rated capacity, these are the possible reasons for that:
The battery's cell imbalance causes premature low-voltage alarms, which in turn causes the BMS to turn loads off.
Please refer to section How to recover an imbalanced battery.
The battery is old and is near its maximum cycle life.
Check how long the system has been in operation, how many cycles the battery has gone through and to what average depth of discharge the battery has been discharged. A way to find this information is to look at the history of a battery monitor (if available).
The battery has been discharged too deeply, and one or more cells in the battery are permanently damaged.
These bad cells will have a low cell voltage faster than the other cells, and this will cause the BMS to turn loads off prematurely. Has the battery perhaps been through a very deep discharge event?
6.1.5. Battery very low terminal voltage
If the battery is discharged too deeply, the voltage will fall well below 12V (24V). If the battery has a voltage of less than 10V (20V or 40V respectively for 24V and 48V batteries) or if one of the battery cells has a cell voltage below 2.5V, the battery will have permanent damage. This will invalidate the warranty. The lower the battery or cell voltage is, the more damage to the battery will be.
You can try to recover the battery by using the below low-voltage recharge procedure. Be aware that this is not a guaranteed process, recovery might be unsuccessful, and there is a realistic chance that the battery has permanent cell damage resulting in a moderate to severe capacity loss after the battery has been recovered.
Charge procedure for recovery after low voltage event:
This recovery charge procedure can only be performed on an individual battery. If the system contains multiple batteries, repeat this procedure for each individual battery.
Warning
This process can be risky. A supervisor must be present at all times.
Set a charger or power supply to 13.8V (27.6V, 55.2V).
In case any of the cell voltages is below 2.0V, charge the battery with 0.1A until the voltage of the lowest cell increases to 2.5V.
A supervisor must monitor the battery and stop the charger as soon as the battery is getting hot or bulging. If this is the case, the battery is unrecoverably damaged.
Once the voltage of the lowest cell has increased above 2.5V, increase the charge current to 0.1C.
For a 100Ah battery, this is a charge current of 10A.
Connect the battery to a BMS and ensure that the BMS has control over the battery charger.
Make a note of the initial battery terminal voltage and battery cell voltages.
Start the charger.
The BMS might turn the charger off, then on again for a short time and then off again.
This can occur many times over and is normal behaviour in case of a significant cell imbalance.
Make a note of the voltages at regular intervals.
The cell voltages should increase during the first part of the charging process.
If the voltage of any of the cells does not increase in the first half hour, consider the battery unrecoverable and abort the charging procedure.
Check the battery temperature at regular intervals.
If you see a sharp increase in temperature, consider the battery unrecoverable and abort the charging procedure.
Once the battery has reached 13.8V (27.6V, 55.2V), increase the charge voltage to 14.2V (28.4V, 56.8V) and increase the charge current to 0.5C.
For a 100Ah battery, this is a charge current of 50A.
The cell voltages will increase more slowly; this is normal during the middle part of the charge process.
Leave the charger connected for 6 hours.
Check the cell voltages; they should all be within 0.1V of each other.
If one or more cells have a much higher voltage difference, consider the battery damaged.
Let the battery rest for a few hours.
Check the voltage of the battery.
It should comfortably sit above 12.8V (25.6V, 51.2V), like 13.2V (26.4V, 52.8V) or higher. And the cell voltages should still be within 0.1V of each other.
Let the battery rest for 24 hours.
Measure the voltages again.
If the battery voltage is below 12.8V (25.6V, 51.2V) or there is a noticeable cell imbalance, consider the battery damaged beyond recovery.
6.1.6. Battery is close to end-of-cycle life or has been misused
As a battery ages, its capacity will reduce, and eventually, one or more battery cells will become faulty. Battery age is related to how many charge/discharge cycles the battery has been through. A battery can also have a reduced capacity or faulty cells if it has been misused, for example, if it has been discharged too deeply.
To determine what could have caused a battery issue, start by checking the battery history by looking at the history of a battery monitor or a Lynx Smart BMS.
To check if the battery is close to its cycle life and if the battery has been misused:
For more info on the life cycle see chapter Technical data. |  |
6.2. BMS issues
6.2.1. The BMS frequently disables the battery charger
A well-balanced battery does not disable the charger, even when it is fully charged. However, when the BMS frequently disables the charger, this indicates cell imbalance.
Check the cell voltages of all batteries connected to the BMS using VictronConnect.
In case of moderate or large cell imbalance, it is expected behaviour that the 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; 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. This behaviour will continue until all cells are fully charged and balanced. This process might take several hours. It depends on the level of imbalance. This process can take up to 12 hours in case of serious imbalance. Balancing will continue throughout this process, even 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 overvoltage.
6.2.2. 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 batteries connected to the BMS.
6.2.3. The BMS is prematurely turning loads off
This could be because of a cell imbalance.
When a cell's voltage falls below the battery's minimum limit of 2.6V, the BMS turns off the load.
Check the cell voltages of all batteries connected to the BMS using the VictronConnect app.
Note
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.
6.2.4. The BMS is displaying an 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, check that the cell voltages and temperatures of all connected batteries are within range. If they are all in range, then follow one of the following procedures.
Also consider that once there has been a cell undervoltage alarm, the cell voltage of all cells needs to be increased to 3.2V before the battery clears the undervoltage alarm.
A way to rule out if a fault is originating from a faulty BMS or a faulty battery is to check the BMS using one of the following BMS test procedures:
Single battery and BMS check:
Disconnect both BMS cables from the BMS.
Connect a single BMS extension cable between both BMS cable connectors. The BMS cable should be connected in a loop, as shown in the diagram below. The loop tricks the BMS into thinking that a battery is connected without any alarms.
The BMS is faulty if the alarm is still active after the loop has been placed.
If the BMS has cleared the alarm after the loop has been placed, the battery is faulty.
Multiple batteries and BMS check:
Bypass one of the batteries by disconnecting both its BMS cables
Connect the BMS cables of the neighbouring batteries (or battery and BMS) to each other, effectively bypassing the battery.
Check if the BMS has cleared its alarm.
Repeat this for the next battery if the alarm has not been cleared.
The BMS is faulty if the alarm is still active after all batteries have been bypassed.
If the BMS clears its alarm when a particular battery is bypassed, that particular battery is faulty.
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Eliminating a BMS error by bypassing a suspect battery
6.2.5. How to test if the BMS is functional
Disconnect one of the battery BMS cables and see if the BMS will go into alarm mode.
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Check BMS functionality by deliberately disconnecting a BMS cable