Victron Energy Battery Balancer

Battery bank life can be significantly shortened by charging imbalance of individual batteries.

This is a situation where you have 12 V batteries in series or series-parallel (not just in parallel!).

In such a system, a single 12 V battery with a slightly higher internal resistance can cause undercharging to full state for parallel-arranged batteries and overcharging for series-arranged batteries.

New battery cells or whole batteries in series have almost identical initial characteristics.

Their minor differences will even out during the absorption or equalization phase of charging. However, large differences can lead to excessive gassing caused by overcharging in more highly charged batteries and undesirable sulphation in less highly charged batteries caused by undercharging.

The solution is balanced charging using a battery balancer.

This balances the state of charge of two 12 V batteries in series or several parallel rows of batteries in series.

When the charging voltage rises to more than 27.3 V in a 24 V system, the battery balancer is activated and compares the voltage of the two batteries in series.

The balancer can redirect a current of up to 0.7 A from one battery (or batteries connected in parallel) with a higher voltage to the other battery.

The different charging currents result in the same final state of charge for all batteries.

Battery balancers can also be arranged in parallel for more complex systems. Thus, for a 48 V system, a total of three balancers are used (see diagrams).

Explanation of the LED indicators:

Green LED: the balancer is active and the measured voltage is above 27.3 V.

Upper orange LED: the voltage deviation is greater than 0.1 V

Lower orange LED: voltage deviation is greater than 0.1 V

Red LED: alarm triggered if the difference between the monitored batteries is greater than 0.2 V. The alarm persists until the difference is less than 0.14 V or the system voltage drops to less than 26.6 V

Meaning of alarm relay:

In the standard state it is open (inactive). It is closed (activated) when the red LED lights up, i.e. when the voltage difference between the batteries is greater than 0.2 V. When the red LED goes off, the relay is opened (deactivated) again (the voltage difference between the batteries is less than 0.14 V).

Alarm reset:

Alarm deactivation is achieved by interconnecting the outputs marked RESET. This can be done by means of a switch.

Installation:

The battery balancer(s) must be installed on a well-ventilated vertical surface close to the batteries (but not directly above the batteries due to the possible influence of battery gases!)

If required, install alarm contact wiring and reset wiring.

Use a minimum of 0.75 mm2 cable to connect the negative, positive and medium poles (in that order!)

The balancer is ready for operation. If the voltage on any of the monitored batteries (strings) rises above 27.3 V (during charging), the green LED will illuminate, indicating that the balancer is activated.

In this situation, if the deviation of the batteries (strings) is greater than 50 mV, active balancing, i.e. compensation of the battery (string) difference, starts.If the deviation reaches 100 mV, one of the orange LEDs is activated.

A deviation greater than 200 mV triggersthose alarm relays.

In series-parallel battery arrangements, the intermediate interconnecting wiring between the parallel rows must be sized to handle the appropriate current if part of the battery is disconnected.

Specifications:

Input voltage range: up to 18 V per battery, 36 V total.

Balancer activation voltage level: 27.3 V ±1%

Balance deactivation voltage level: 26.6 V ±1%

Power consumption in deactivated state: 0.7 mA

Power consumption in activated state: 50 mV

Maximum balancing current: 0.7 A at a deviation of 100 mV or more

Voltage deviation for alarm triggering: 200 mV

Alarm trip voltage deviation: 140 mV

Alarm relay: 60V/1 A, standard open

Alarm relay tripping method: connection of two outputs marked RESET

Over-temperature protection: yes

Operating temperature range: -30 to +50 °C

Maximum humidity: up to 95% (non-condensing)

Cover colour: blue (RAL 5012)

Connection contacts: 6 mm2/AWG10, screw fixing

Degree of protection: IP22

Weight: 0.4 kg

Dimensions (height x width x depth): 100 x 113 x 47 mm