Precautions for series and parallel connection of lithium batteries

　　Do not use batteries of different brands together.

　　Do not use batteries with different voltages together.

　　Do not mix new and old lithium batteries with different capacities.

　　Batteries made of different chemical materials cannot be mixed, such as nickel hydrogen and lithium batteries.

　　When the battery is low, replace all batteries.

　　Use lithium battery protection board with corresponding parameters.

　　Select batteries with the same performance. Generally, lithium batteries used in series and parallel need to be paired with lithium battery cells. Matched standard: voltage difference ≤ 10mV, internal resistance difference ≤ 5m Ω, capacity difference ≤ 20mA

　　1. Lithium batteries with different voltages are connected in series

　　Due to the consistency problem of lithium batteries, the batteries in the same system (such as ternary or iron lithium) should be grouped in parallel and in series, and those with the same voltage, internal resistance and capacity should also be selected for grouping. Batteries with different voltage platforms and different internal resistances are used in series, which will cause a battery to be fully charged and discharged first in each cycle. If there is a protection board and no failure occurs, the capacity of the whole group will be reduced. If there is no protection board, the battery will inevitably be overcharged or discharged and then damaged.

　　2. Parallel connection of lithium batteries with different capacities

　　If different capacity or new and old lithium batteries are used together, liquid leakage and zero voltage may occur. This is because during the charging process, the capacity difference causes some batteries to be overcharged, some batteries are not fully charged, and some batteries with high capacity are not fully discharged, while those with low capacity are overcharged. In such a vicious cycle, the battery is damaged and leaks or has low (zero) voltage.

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