HA01 Battery equaliser for 12v batteries ideal for small solar backup. This is used for batteries which are connected in series to keep the voltage of batteries equal when charging or discharging. When connected in series battery voltages will vary due to the differences in cell chemical composition and temperature, each battery self discharge rate will  also be different. These differences will cause battery pack to become unbalanced, this imbalance will result in undercharging and overcharging of the batteries resulting in sulfation and premature corrosion of the plates. The voltage difference will increase over time and subsequent charging cycles. This will result in premature failure of the batteries. 

HA01 battery balancer is an energy transfer type equaliser.

That means that the equaliser starts to work when there is a  20mV difference between the two batteries. The voltage difference will cause current to flow from a higher voltage battery to the lower voltage, eventually reaching equilibrium. It can be permanently connected to the battery system to keep the system voltage balanced automatically and requires no maintenance. 

One equaliser connects 2 batteries in series and can be connected with batteries in parallel for larger capacity balancing. 

Several equalisers can be connected in series for larger voltage balancing. Battery equaliser can be used for 24V, 36V, 48V and any other 

N*12V battery system.

1 piece for 24V system; 

2 pieces for 36V system;

3 pieces for 48V system;

 Battery balancing explained here in a youtube video: https://www.youtube.com/watch?v=0KSFitqvap0 

Specifications:

Battery nominal voltage: 2*12V 

Optimising current: 0-5A 

Quiescent current : <3mA 

Dimensions: 70*70*27 mm 

Protection: Reverse polarity protection 

Low Voltage Disconnect: 10V