4. Installation
4.1. Preparation
4.1.1. What's in the box
Unpacking and handling the battery
Take care when unpacking the battery. Batteries are heavy. Do not lift the battery by its terminals or by its BMS cables. The battery has two carry handles on either side of the battery. The weight of the battery can be found in the Technical data chapter.
Familiarise yourself with the battery. The battery terminals, on the top of the battery, have indicators for correct polarity: a “+” symbol for the positive and a “-” symbol for the negative terminal.
The battery has two BMS cables. These cables are used for communication with the BMS. One cable has a male 3-pole connector and the other has a female 3-pole connector. Depending on the battery model, the BMS cables are located on one side of the battery or on two opposite sides of the battery.
Pay attention to the location of the BMS cables when handling the battery. The BMS cables can easily get damaged.

Top view and side views showing battery terminals (+ and -), BMS cables (A) and carry handles (B)
4.1.2. Download and install the VictronConnect app
The VictronConnect app is used to monitor the battery, change battery settings and update firmware.
Download the VictronConnect app for Android, iOS or macOS from their respective app stores. For more information about the app see the VictronConnect product page.
The VictronConnect app communicates with the battery via Bluetooth
4.1.3. Update the battery firmware
Before the battery is going to be used, it is important to check if the battery has the most up to date firmware. The firmware can be checked and updated with the VictronConnect app. Also make sure you have the latest VictronConnect version. This ensures that the latest battery firmware version is available.
The VictronConnect app might ask, on first connection, to update firmware. If this is the case, let it perform a firmware update. If it did not automatically update, check if the firmware is already up to date using the following procedure:
Connect to the battery.
Click on the settings symbol
to go to the Settings page.
Click on the option symbol
to go to the Product info.
Check if you are running the latest firmware and look for the text: “This is the latest version”.
If the battery does not have the most up to date firmware, perform a firmware update.
![]() |
Updating battery firmware
4.1.4. Charge batteries before use
If multiple batteries are going to be connected in series or in series/parallel, each individual battery needs to be fully charged before all batteries are interconnected.
How to charge batteries before use
Warning
Always use a BMS controlled charger when individually charging lithium batteries.
Initial charge procedure:
Connect each individual battery to a charger or to an inverter/charger and to a BMS (and repeat for every other battery).
Refer to the BMS manual on how to set the BMS up.
Set the charger to the charge profile as indicated in below table.
Ensure that the battery, the BMS and the charger are communicating with each other. Check this by disconnecting one of the battery BMS cables from the BMS and verify that the charger turns off. Then reconnect the BMS cable and verify that the charger turns back on.
Turn the charger on and check that the charger is charging the battery.
Note that during charging, the charger might repeatedly be turned off, and then on again by the BMS should there be an imbalance between the battery cells. This will manifest as follows: The charger will be on for a short period of time, then the charger will be off for a few minutes and then on again for a short time and so on. This might be repeated many times. This is nothing to be worried about and is part of the charge process. If the cells are balanced, the charger will not be turned off until the battery is fully charged.
The battery is fully charged when the battery charger has reached the float stage and the VictronConnect app battery cell status is "balanced". In case the battery cell status is "unknown" or "imbalanced", then the battery charger needs to be restarted multiple times until the battery cell status is "balanced".
Initial charge using a BMS
Charger or inverter/charger settings for initial charge with a BMS (these are the same as the normal charge settings):
Recommended charger settings | |||||
---|---|---|---|---|---|
Battery model | Max. charge current | Charge profile | Absorption voltage | Absorption time | Float voltage |
12.8V - 50Ah | 30A | Lithium, fixed | 14.2V | 2h | 13.5V |
12.8V - 60Ah | 30A | Lithium, fixed | 14.2V | 2h | 13.5V |
12.8V - 100Ah | 50A | Lithium, fixed | 14.2V | 2h | 13.5V |
12.8V - 160Ah | 80A | Lithium, fixed | 14.2V | 2h | 13.5V |
12.8V - 200Ah | 100A | Lithium, fixed | 14.2V | 2h | 13.5V |
12.8V - 300Ah | 150A | Lithium, fixed | 14.2V | 2h | 13.5V |
12.8V - 330Ah | 150A | Lithium, fixed | 14.2V | 2h | 13.5V |
25.6V - 100Ah | 50A | Lithium, fixed | 28.4V | 2h | 27.0V |
25.6V - 200Ah | 100A | Lithium, fixed | 28.4V | 2h | 27.0V |
Why charge batteries before use
Lithium batteries are only approximately 50% charged when shipped from the factory. This is a transportation safety requirement. But due to differences in transportation routes and warehousing, the batteries do not all have the same state of charge by the time they are installed.
The battery cell balancing system is only able to correct small differences in state of charge from one battery to another. A large imbalance, as can be the case with new batteries, will not be corrected. Please note that this type of imbalance, a different state of charge between batteries, is a different type of imbalance than if the cells within the battery are imbalanced.
Note
Charging the batteries before use is not needed for a single battery or for individual batteries connected in parallel (none connected in series).
4.2. Physical installation
4.2.1. Mounting
Mounting must meet the following requirements:
The battery must be mounted in an upright position.
The battery is only suitable for indoor use and needs to be located in a dry location.
Batteries are heavy. When moving the battery into its destined location, use suitable handling equipment for transportation.
Ensure adequate and secure mounting as the battery can become a projectile if involved in an accident.
Batteries produce a certain amount of heat when they are charged or discharged. Keep a 20mm space on each side of the battery for ventilation purposes.
4.3. Electrical installation
4.3.1. Connecting battery cables
The positive terminal is indicated by a “+” (plus) symbol and the negative terminal is indicated by a “-“ (minus) symbol. Observe the battery polarity when connecting the battery terminals to a DC system or to other batteries. Take care not to short circuit the battery terminals. Connect the cables as indicated in the diagram on the right:
| ![]() Battery cable connection | ![]() Battery terminals |
When tightening the bolts, use the correct torque, as indicated in below table, and use insulated tools that match the bolt's spanner size.
Battery model | Thread | Torque |
---|---|---|
12.8V - 50Ah | M8 | 10Nm |
12.8V - 60Ah | M8 | 10Nm |
12.8V - 100Ah | M8 | 10Nm |
12.8V - 160Ah | M8 | 14Nm |
12.8V - 200Ah | M8 | 14Nm |
12.8V - 300Ah | M10 | 20Nm |
12.8V - 330Ah | M10 | 20Nm |
25.6V - 100Ah | M8 | 10Nm |
25.6V - 200Ah | M8 | 14Nm |
Cable cross sectional area and fuse ratings
Use battery cables with a cross sectional area that matches the currents that can be expected in the battery system.
Batteries can produce very large currents; it is therefore necessary that all electrical connections to a battery are fused.
The battery fuse rating has to match the current rating of the battery cable that has been used. Both the battery cable and the fuse have to also match the expected maximum system currents.
For more information on cable cross sectional area, fuse types and fuse ratings see the Wiring Unlimited book.
The battery maximum discharge rating is indicated in the table below. The system current and therefore also the fuse rating should not exceed this current rating. The fuse has to match the lowest current rating, being the cable current rating, the battery current rating or the system current rating.
Battery model | Maximum current rating |
---|---|
12.8V - 50Ah | 100A |
12.8V - 60Ah | 120A |
12.8V - 100Ah | 200A |
12.8V - 160Ah | 320A |
12.8V - 200Ah | 400A |
12.8V - 300Ah | 600A |
12.8V - 330Ah | 660A |
25.6V - 100Ah | 200A |
25.6V - 200Ah | 400A |
Connecting a single battery
| Single battery |
Connecting multiple batteries in series
| Multiple batteries in series |
Connecting multiple batteries in parallel
| Multiple batteries in parallel |
Connecting multiple batteries in series/parallel
| Multiple batteries in series/parallel Do not interconnect midpoints or other between string points |
Battery banks consisting of different batteries
When constructing a battery bank, ideally all batteries should be of the same capacity, age and model. However, there are situations where this is not possible, such as when capacity need to be expanded by adding more batteries, or when a single battery in a battery bank needs to be replaced. In these cases, follow the guidelines in the table below.
Battery bank type | Different capacities allowed? | Different ages allowed? |
---|---|---|
Parallel | Yes | Yes |
Series | No1) | Yes2) |
Series/parallel - within a series string | No1) | Yes2) |
Series/parallel - in case a whole series string is replaced or added | Yes | Yes |
1) All batteries must have the same capacity rating and the same part number 2) The age difference should not exceed 3 years |
Background information:
When batteries with different capacities, or a big age difference (old batteries have a reduced capacity), are connected in series, an imbalance will occur between the batteries. This imbalance will increase over time and causes a reduction of the overall battery capacity. In theory, the battery with the smallest capacity will determine the overall capacity of a series battery string. But in reality, the imbalance will reduce the overall battery bank capacity even further. For example, if a 50Ah battery is connected in series with a 100Ah battery, the overall string capacity is 50Ah. But over time the batteries become imbalanced, and when the imbalance has become, let's say, 10Ah, the overall battery capacity will be 50Ah-10Ah = 40Ah. The cells of the fullest battery will have an overvoltage during charging, while they are not able to send the excess voltage to the other battery cells. The BMS will constantly interfere, and this results in that the emptiest battery is being discharged too far and the fullest battery is being overcharged.
Tip
Adding a Battery Balancer to a series string will reduce imbalance.
4.3.2. Connect the BMS
Each battery has two BMS cables with an M8 male and M8 female connector that need to be connected to the BMS.
BMS cables on either side or on one side | Female and male BMS connector Connected BMS connectors |
How to connect the cables:
For a single battery, connect both BMS cables directly to the BMS.
For a battery bank consisting of multiple batteries, interconnect each battery (daisy chain) and connect the first and last BMS cable to the BMS. The batteries can be interconnected in any order.
If the BMS is too far away for the cables to reach, use the optional extension cables. The BMS extension cables are available as a pair and come in a variety of lengths. For more information see the BMS extension cable product page.
Single battery BMS connection | ![]() Two battery BMS connection (with optional extension cables) | ![]() Multiple battery BMS connection |
4.4. Configuration
4.4.1. Battery settings
The default settings in the battery are suitable for almost all applications. There is no need to change these settings unless the application requires very specific conditions.
If settings need to be changed, use the VictronConnect app. To access the settings, click on the settings symbol .
VictronConnect battery settings
Allowed-To-Discharge cell voltage
This is the lowest battery cell voltage, at which discharging the battery is disallowed.
A lithium battery cell will be damaged if the cell voltage drops too low. As soon as one of the cells reaches the "Allowed-To-Discharge" voltage, the BMS will disable all loads by sending a signal to the load or to the load disconnection device.
The default value is 2.80V, the range is 2.60V to 2.80V.
We recommend not to change this setting. The only scenario where a lower setting might be applicable is in emergency systems, where it could be a requirement to discharge the battery as far as possible and therefore sacrificing part of the battery's overall lifetime.
If the "Allowed-To-Discharge" cell voltage is set to a low value, there will be less reserve capacity than when it is set at a higher value, for example:
At 2.8V cell voltage there is approximately 3% remaining capacity in the battery.
At 2.6V there is about 1% remaining capacity in the battery.
More reserve capacity is important. When there is less reserve capacity, the battery will need to be recharged almost straight away after a low voltage shutdown has occurred. If the battery is not recharged, it will further discharge due to self-discharge and quicker reach the point where one or more cells are damaged due to low cell voltage. This will lead to a permanent reduction of battery capacity and/or lifetime.
Cell under voltage pre-alarm threshold
When the cell voltage drops below this threshold, a pre-alarm signal is sent to the BMS. The purpose of the pre-alarm is to warn the user that the system is about to shut down due to under voltage. For more details see chapter The pre-alarm signal.
The default value is 3.10 V and the range is 2.80V to 3.15V.
If the pre-alarm threshold is set at a higher voltage, the warning will come earlier than when it is set at a lower voltage. An earlier warning will give the user more time to take action and avert the imminent shutdown. In any case, there is at least a minimum of 30 seconds between pre-alarm and system shutdown.
Allowed-To-Charge minimum temperature
This setting defines the lowest temperature at which the BMS allows battery charging. A lithium battery cell will sustain permanent damage when it is charged at temperatures below 5°C.
The default value is 5°C and the range is -20°C to +20°C.
Warning
Setting this temperature below 5°C will void the warranty.
Battery temperature offset
This setting can be used to set an offset to improve the accuracy of the battery temperature measurement.
The default value is 0°C and the range is -10°C to +10°C.
4.4.2. Charger settings
Set all charge sources to the following charge parameters:
Recommended charger settings | |||||||
---|---|---|---|---|---|---|---|
Battery model | Recommended charge current | Max. charge current | Charge profile | Absorption voltage | Absorption time | Float voltage | Storage voltage * |
12.8V - 50Ah | 30A | 100A | Lithium, fixed | 14.2V | 2h | 13.5V | 13.5V |
12.8V - 60Ah | 30A | 120A | Lithium, fixed | 14.2V | 2h | 13.5V | 13.5V |
12.8V - 100Ah | 50A | 200A | Lithium, fixed | 14.2V | 2h | 13.5V | 13.5V |
12.8V - 160Ah | 80A | 320A | Lithium, fixed | 14.2V | 2h | 13.5V | 13.5V |
12.8V - 200Ah | 100A | 400A | Lithium, fixed | 14.2V | 2h | 13.5V | 13.5V |
12.8V - 300Ah | 150A | 600A | Lithium, fixed | 14.2V | 2h | 13.5V | 13.5V |
12.8V - 330Ah | 150A | 400A | Lithium, fixed | 14.2V | 2h | 13.5V | 13.5V |
25.6V - 100Ah | 50A | 200A | Lithium, fixed | 28.4V | 2h | 27.0V | 27.0V |
25.6V - 200Ah | 100A | 400A | Lithium, fixed | 28.4V | 2h | 27.0V | 27.0V |
* Storage stage is not per se needed for a lithium battery, but if the charger has a storage mode, set it at the same as the float voltage.
4.5. Commissioning
Once all connections have been made, the system wiring needs to be checked, the system needs to be powered up and the BMS functionality needs to be checked. Follow this checklist:
Check polarity of all battery cables. | |
Check cross sectional area of all battery cables. | |
Check if all battery cable lugs have been crimped correctly. | |
Check if all battery cable connections are tight (don’t exceed maximum torque). | |
Tug slightly on each battery cable and see if the connections are tight. | |
Check all BMS cable connections and make sure the connector screw rings are screwed all the way down. | |
Connect with VictronConnect to each battery. | |
Check if each battery has the most up to date firmware. | |
Check if each battery has the same settings. | |
Connect the system positive and negative DC cable to the battery (or battery bank). | |
Check the string fuse(s) rating (if applicable). | |
Place the string fuse(s) (if applicable). | |
Check the main fuse rating. | |
Place the main fuse. | |
Check if all battery charge sources have been set to the correct charge settings. | |
Turn on all battery chargers and all loads. | |
Check if the BMS is powered up. | |
Disconnect a random BMS cable and verify that the BMS is turning off all charge sources and all loads. | |
Reconnect the BMS cable and check if all charge sources and loads turn back on. |