Passive balancing and active balancing methods of CR2032 button cell protection board

　　Passive balancing and active balancing methods for CR2032 button cell protection boards. In traditional energy-consuming BMS systems, the balancing method is mainly passive balancing. Among them, the CR2032 button cell protection plate balancing system, which plays a key role, has also attracted widespread attention. Currently, there are two methods of balancing multi-series battery systems on the market: traditional passive balancing and active balancing.

　　Passive balancing and active balancing methods of CR2032 button cell protection board

　　1. Passive equilibrium

　　Passive equalization generally discharges lithium batteries with higher voltages through resistor discharge, releasing power in the form of heat to gain more charging time for other batteries. In this way, the power of the entire system is limited by the battery with the smallest capacity. During the charging process, lithium batteries generally have a charging upper limit protection voltage value. When a certain battery string reaches this voltage value, the CR2032 button cell protection board will cut off the charging circuit and stop charging. If the voltage during charging exceeds this value, which is commonly known as "overcharging", the CR2032 button cell may burn or explode. Therefore, CR2032 button cell protection boards generally have overcharge protection functions to prevent the battery from overcharging.

　　The advantages of passive balancing are low cost and simple circuit design; the disadvantage is that the balance is based on the lowest remaining battery capacity, which cannot increase the capacity of batteries with low remaining capacity, and 100% of the balanced power is wasted in the form of heat.

　　2. Active balancing

　　Active balancing uses power transfer to balance, which has high efficiency and small losses. Different manufacturers have different methods, and the balancing current ranges from 1 to 10?A. Many active balancing technologies currently on the market are immature, resulting in battery over-discharge and accelerated battery degradation. Most active equalizers on the market use the transformer principle and rely on expensive chips from chip manufacturers. In addition to the balancing chip, this method also requires expensive peripheral components such as transformers, which are larger in size and higher in cost.

　　The benefits of active equalization are obvious: high efficiency, energy is transferred, and the loss is only the loss of the transformer coil, which accounts for a small proportion; the equalizing current can be designed to be large, reaching several amps or even 10A, and the equalizing effect is quick. Despite these benefits, active equalization also introduces new problems. The first is the complex structure, especially the transformer solution. How to design the switch matrix required for dozens or even hundreds of battery strings and how to control the driver are all headaches. Nowadays, the price of BMS with active balancing function is much higher than that of passive balancing, which somewhat limits the promotion of active balancing BMS.

　　Passive balancing is suitable for CR2032 button cell pack applications with small capacity and low string count, while active balancing is suitable for power CR2032 button cell pack applications with high string count and large capacity. For BMS, in addition to the important balancing function, the balancing strategy behind it is even more important.

　　Balancing principle of CR2032 button cell protection board

　　Commonly used balancing charging technologies include constant shunt resistor balancing charging, on-off shunt resistor balancing charging, average battery voltage balancing charging, switched capacitor balancing charging, buck converter balancing charging, inductor balancing charging, etc. When charging a group of lithium batteries in series, each battery should be charged evenly, otherwise the performance and life of the entire battery group will be affected during use.

　　During the charging process of lithium batteries, each CR2032 button cell is equipped with a balancing circuit. During charging, the voltage of each battery is controlled through the balancing circuit of the CR2032 button cell protection board, so that each string of batteries remains in the same state, ensuring the safety of the CR2032 button cell. Performance and longevity.

　　If the regulated power supply set by the balancing circuit of the CR2032 button cell protection board is 4.2V, when the CR2032 button cell does not reach 4.2V, each CR2032 button cell continues to charge, the balancing circuit does not work, and the charging current continues to pass through the CR2032 button cell: when the CR2032 button cell When one reaches 4.2V, the balancing circuit starts to work, and it will stabilize the voltage to 4.2V, that is, the charging current no longer passes through the CR2032 button cell.

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