5. Operation
5.1. Setup, Monitoring & Control via VictronConnect
Setup, monitoring and control are done entirely via Bluetooth using the VictronConnect app.
5.1.1. Battery Limits configuration
The individual parameters for the battery limits are explained in the chapter Battery settings and configuration via VictronConnect. It is recommended to leave these parameters at their default settings.
5.1.2. Monitoring the battery
The VictronConnect app can be used to monitor the battery via Bluetooth in two ways:
Via a connected Bluetooth link to the battery: requires pairing between the mobile device and the battery.
Via Instant readout: show the most relevant data of the battery in the product list page via Bluetooth without having to establish a connection.
Paired Bluetooth connection
When connected to the battery via VictronConnect, it will show the following parameters:
|  Paired connection |
Note that warning, alarm or error messages are only shown while actively connected to the battery via VictronConnect. The app is not active in the background nor when the screen is off.
Instant readout
Instant readout via Bluetooth offers the advantage that the most important data is shown instantly in the VictronConnect app (together with data of other devices that are compatible), without having to connect directly to the battery. In addition, it offers a better range than a regular connection.
Instant readout is disabled by default and can be enabled in the product info page. See also the chapter Instant readout in the VictronConnect manual.
Instant readout will show the following parameters:
|  Instant readout |
5.1.3. Updating the battery firmware
Please see the chapter Update the battery firmware for details.
5.2. Charging the battery and recommended charger settings
Recommended battery chargers
Ensure your charger supplies the correct current and voltage for the battery, so do not use a 24V charger for a 12V battery.
It is also recommended that the charger has a charging profile/algorithm that matches the battery chemistry (LiFePO4) or a custom profile that can be adjusted to match the appropriate charging parameters of the lithium battery. All Victron chargers (AC Chargers including Inverter/Chargers, Solar Chargers and DC-DC Chargers) have these preset charging profiles built-in. Make sure this profile is selected. See also the respective manuals of the chargers.
Recommended charger settings
The important charging parameters are absorption voltage, absorption time and float voltage.
Absorption voltage: 14.2V for a 12.8V lithium battery (28.4V / 56.8V for a 24V or 48V system
Absorption time: 2 hours. 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. Please see the Cell balancing chapter for a more detailed explanation why cell balancing is needed and how cell balancing works.
Float voltage: 13.5V for a 12.8V lithium battery (27V / 54V for a 24V or 48V system)
Some charging profiles offer a storage mode. This is not needed for a lithium battery, but if the charger has a storage mode then set this to the same value as the float voltage.
Some chargers have a bulk voltage setting. If this is the case, set the bulk voltage to the same value as the absorption voltage.
Temperature-compensated charging is not required for lithium batteries; Disable temperature compensation or set temperature compensation to 0mV/°C in your battery chargers.
Recommended charging current
Even if the battery can be charged with a much higher charging current (see the Technical data for the max. continuous charge current), we recommend a charging current of 0.5C, which will fully recharge a completely empty battery in 2 hours. A charging current of 0.5C for a 100Ah battery corresponds to a charging current of 50A.
Charging profile
A typical charging profile resulting from the above then looks like the graph below:
After starting the charger, it takes two hours to reach absorption voltage
Another two hours of absorption time to give the balancer time to balance the cells properly
At the end of the absorption time, the charging voltage is reduced to 13.5 V float voltage
 |
Lithium battery charge graph
5.3. Discharging
Even though a BMS is used, there are still a few possible scenarios where the battery can be damaged due to over-discharge. Be sure to observe the following warning.
Warning
Lithium batteries are expensive and can be damaged due to over-discharge or overcharge.
Damage due to over-discharge can occur if small loads (such as alarm systems, relays, standby current of certain loads, back current drain of battery chargers, or charge regulators) slowly discharge the battery when the system is not in use.
A shutdown due to a low cell voltage by the BMS should always only be used as a last resort to prevent imminent battery damage. We recommend not letting it get that far in the first place and instead using the remote on/off function of the BMS as a system on/off switch when you leave the system unattended for extended periods of time, or even better, using a battery switch, pulling the battery fuse(s) or disconnection the battery positive terminal when the system is not in use. Before doing this, make sure that the battery is sufficiently charged so that there is always enough reserve capacity in the battery.
A residual discharge current is especially dangerous if the system has been discharged completely and a low cell voltage shutdown has occurred. After shutdown due to low cell voltage, a capacity reserve of approximately 1Ah per 100Ah battery capacity is left in the battery. The battery will be damaged if the remaining capacity reserve is drawn from the battery, for example, a residual current of just 10mA can damage a 200Ah battery if the system is left discharged for more than 8 days.
Immediate action (recharge the battery) is required if a low cell voltage disconnect has occurred.
Recommended discharge current
We recommend a continuous discharge current of ≤1C even if the maximum allowed discharge current is much higher (see Technical data). When using a higher discharge rate, the battery will produce more heat than when a low discharge rate is used. More ventilation space is needed around the batteries and depending on the installation, hot air extraction or forced air cooling might be required. Also, some cells might reach the low voltage threshold quicker than other cells. This can be because of a combination of elevated cell temperature and battery ageing.
Depth of Discharge (DoD)
The depth of discharge has a decisive influence on the service life of the lithium battery. The higher the depth of discharge, the lower the number of possible charge cycles. See the Technical data for the possible number of charge cycles depending on the depth of discharge.
Effect of temperature on battery capacity
The temperature affects the battery capacity. The nominal capacity data of the respective battery model in the datasheet is based on 25°C at a discharge rate of 1C. These numbers are reduced by ~20% at 0°C and reduce even further to ~50% at -20°C. However, since SoC is not calculated in the battery but in the battery monitor, which therefore does not show the actual SoC, it is much more important to keep an eye on the battery and cell voltages when discharging at low temperatures.
5.4. Observe the operating conditions
The operating conditions for charging and discharging the battery must also be observed.
These are in detail:
Discharge is only permitted in a temperature range of -20°C to +50°C.
Ensure that all loads are switched off accordingly when the temperature exceeds the limits (ideally loads have a remote on/off port controlled by the BMS).
Charging the battery is only allowed in a temperature range of +5°C to +50°C.
Ensure that all chargers are switched off accordingly when the Allowed-To-Charge minimum temperature limit is reached (ideally the charger has a remote on/off port controlled by the BMS) to prevent charging below +5°C or above 50°C.
5.5. Battery care
Once the battery is in operation, it is important to take proper care of the battery to maximise its lifetime.
These are the basic guidelines:
Prevent total battery discharge at all times.
Familiarise yourself with the pre-alarm feature and act when the pre-alarm is active to prevent a system shutdown.
If the pre-alarm is active or if the BMS has disabled the loads, make sure that the batteries are recharged immediately. Minimise the time the batteries are in a deep discharged state.
The batteries must spend at least 2 hours in absorption charge mode each month to ensure sufficient time in balancing mode. For detailed information on how the balancing process works, see the Cell balancing chapter.
When leaving the system unattended for some time, make sure to either keep the batteries charged during that time or make sure the batteries are (almost) full and then disconnect the DC system from the battery.