Battery Balancer

The Victron Energy Battery Balancer is designed to equalize the state of charge of 12 V batteries connected in series, typically in 24 V or 48 V systems. Its function is to prevent voltage imbalances that can reduce battery life by causing overcharging or undercharging. It ensures all batteries maintain a uniform state of charge.

When the charging voltage of a 24V battery system exceeds 27.3V, the Battery Balancer activates. It compares the voltage of batteries connected in series and draws up to 0.7A from the battery (or batteries connected in parallel) with the highest voltage. This differential charging current allows all batteries to converge toward the same state of charge.

The Battery Balancer is designed for battery systems made up of 12V batteries connected in series, such as 24V systems. For 48V systems, it is possible to connect multiple Battery Balancers in parallel.

Yes, multiple Battery Balancers can be connected in parallel to balance larger battery systems. For example, a 48V battery bank can be balanced with three Battery Balancers.

The Battery Balancer activates when the charging voltage of a 24V system reaches 27.3V (+/- 1%). It deactivates when the system voltage drops below 26.6V (+/- 1%).

The balancing process starts as soon as a voltage deviation of more than 50 mV is detected between the batteries. The maximum balancing current of 0.7A is reached when the deviation exceeds 100 mV.

The Battery Balancer has dimensions of 100 x 113 x 47 mm (height x width x depth) and weighs 0.4 kg.

The Battery Balancer has an IP22 protection rating. This means it is protected against solid objects larger than 12.5 mm and against dripping water when tilted up to 15° from vertical. It is not designed to withstand direct exposure to intense water jets.

The Battery Balancer must be installed on a well-ventilated vertical surface, near the batteries. It is important not to install it directly above the batteries due to potential corrosive gases.

Use cables with a cross-section of at least 0.75 mm² for the negative, positive, and midpoint connections. For UL compliance, these cables must also be fused near the batteries with a 10A fuse suitable for DC current (e.g., an automotive blade fuse from the Littelfuse ATOF series with an inline fuse holder).

For a 24V system with two 12V batteries in series, you must connect the Battery Balancer to the positive and negative terminals of the entire system, as well as to the midpoint between the two 12V batteries. The recommended wiring order is negative, positive, then the midpoint.

The Battery Balancer is equipped with LED indicators:

A green LED lights up when the system is powered (battery voltage > 27.3V). Orange LEDs light up if a voltage deviation greater than 0.1V is detected and the balancing process is active. A red LED lights up in case of alarm, indicating a voltage deviation greater than 0.2V.

The red LED indicates an alarm, signaling a voltage deviation greater than 0.2V. The alarm remains active until the deviation drops below 0.14V or the system voltage falls below 26.6V. A normally open alarm relay (60V / 1A) closes when the red LED lights up and opens when it turns off.

Yes, the Battery Balancer has two terminals for connecting a pushbutton. By interconnecting these two terminals, you can reset the alarm relay. The reset condition remains active until the alarm is cleared.

The Battery Balancer can operate within a temperature range from -30°C to +50°C.

If an alarm is triggered on a new battery bank, this is likely due to initial state-of-charge differences. If the voltage difference between the lowest and highest cell exceeds 0.9V, it is advisable to stop charging and charge the batteries individually, or significantly reduce the charge current to allow the batteries to balance over time.

If the issue persists, you may consider the following actions:

For a series-parallel connection, disconnect the parallel wiring from the midpoint and measure the individual midpoint voltages during the absorption charge to isolate batteries requiring additional charging.Test and charge all batteries individually.Connect one or more additional Battery Balancers in parallel (on average, one balancer can manage up to three parallel chains of 200 Ah).

Yes, the Battery Balancer can be used in combination with the mid-point monitoring function of the BMV-702 battery monitor. The BMV-702 measures mid-point deviation and can trigger visual/acoustic alarms or close a relay contact for remote alarms, providing enhanced control and visibility.

When the Battery Balancer is off (in standby mode), its current draw is very low, at just 0.7 mA.

The Battery Balancer can provide a maximum balancing current of 0.7A when the voltage deviation between batteries connected in series exceeds 100 mV.