The battery equalizer is used to connect the batteries in series to keep the battery voltage equal when charging or discharging. When the batteries work in series, the battery voltage may not change with the difference of each battery in the chemical composition and temperature of the battery. And the self-discharge rate of each battery is also different. So even if the batteries are not working, the voltages of the batteries connected in series will be different. These differences can cause the battery to lose balance, which means that one battery may be overloaded. And other batteries are fully charged. With the repeated charging and discharging process of the battery, the voltage difference will increase, which will cause the battery to fail prematurely This battery equalizer is an energy transfer type equalizer, which can compensate for the batteries on both sides. When there is a voltage of 10mV between the two batteries, the equalizer starts to work. The current flows from the higher vor3A voltage to the low voltage, and finally reaches equilibrium and can be connected. Equipped with a 24-hour battery system, automatically maintains the system energy balance without manual maintenance The battery equalizer is suitable for lead-acid batteries (VRLA), lithium iron phosphate batteries (LFP), nickel-cadmium secondary batteries (Ni/CD), nickel-hydrogen secondary batteries (Ni/MH), when the voltage is higher than 2.4V, this Means that the equalizer can be used for single-cell batteries from 2.4V to 12V. An equalizer can be connected to 4 batteries at a time. If the battery is less than 4, the extra wires can be left empty (avoid positive and negative poles). Does not affect the balance effect. The equalizer is not affected by the battery connection mode, and can work regardless of whether it is connected in series or in parallel. Material:plastic colour:Black Package Contents: 1 x Battery Equalizer Only the above package content, other products are not included. Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.