HKIVI BMS, battery management system, has the same function as overvoltage/undervoltage protection; short circuit protection; overcurrent protection;temperature check function; heating function; coulomb counter function; balancing function..etc. A good BMS must have balancing function to aintain the consistency of the battery packs. At present, almost all BMS products on the market have balancing functions, which are mainly divided into passive balancing and active balancing.
What is active balancing?
Active balancing, called lossless balancing too, is to balance in the way of energy transfer. Transfering the battery with high energy to the battery with low energy, so as to achieve the blance of the whole group voltage, and almost no energy loss i sinvoled in the transfer process.
Why we call it active balancing?
Regardless of whether the battery is charging, discharging, or not-working conditionl, as long as the pressure difference is bigger than the setting value, balancing function will start. Therefore, as long as there is a pressure difference, the active balancing function should be working 24 hours a day until the pressure difference is less than the setting value.
Balanced current for active balancing
Since active balancing is a way of energy transfer without heat generation, all balanced currents can be larger without affecting heat dissipation. Generally, it is more common for active balanced currents to reach 1~2A.
Because the active balancing is not limited by the charging time, the balancing time is longer, and the balanced current is relatively large, so it is more suitable to use in large-capacity battery packs.
What is passive balancing?
Passive balancing, generally discharges the battery with higher voltage through resistance discharge, releases the power in the form of heat, realizes the balancing of the voltage of the whole group, and strives for more charging time for other batteries.
Why we call it passive balancing?
Passive balancing starts balancing when the battery is almost fully charged, so the working time for balancing is relatively short, from battery charge nearly full to fully charged. Generally, it is about several hours based on different charger.
Blanced current for passive balancing
Usually, passive balancing current anges from 35mA to 200mA, and the bigger balanced current is, the higer temperature the BMS. Passive balancing is resistive energy-consuming balancing, the consumed energy is released by heat. So, during the balanced process, BMS teperature will be high, which means the balanced current can not be large, or the whole temperature of the battery pack will be too high.If the blanced current is too small, the balanceing effect will be very low for large capaciy battery packs, and it takes a long time to balance the battery pack.