What happens when li-ion batteries of different voltages or different capacities are connected in series or in parallel

　　Due to consistency issues, lithium-ion batteries should be grouped in series or in parallel in the same system (such as ternary lithium batteries or lithium iron phosphate). The same voltage, internal resistance and capacity should be selected when grouping

　　Connecting multiple li-ion batteries in parallel will not change the output voltage of the lithium battery pack, but can increase the capacity of the lithium battery pack.

　　Connecting multiple li-ion batteries in series will not change the rated capacity of the lithium battery pack, but can increase the output voltage of the lithium battery pack.

　　The serial use of lithium ion batteries with different voltage platforms and internal resistances will cause one of the lithium ion batteries to be fully charged or empty in each cycle, and the capacity of the entire lithium ion battery pack will be reduced. Lithium ion batteries can be damaged due to overcharging or discharging, and even lead to safety accidents.

　　If different capacity or new and old lithium batteries are used together, leakage and zero voltage of the lithium battery pack may occur. This is due to the difference in capacity during the charging process, causing some lithium batteries to be overcharged, while others are not fully charged. When discharging, some large-capacity lithium batteries are not completely discharged, and the small-capacity lithium batteries are over-discharged. In this vicious cycle, batteries with insufficient capacity will decay faster and even enter irreversible damage.

　　Therefore, when connecting lithium batteries in series or in parallel, pay attention to the above things, especially do not mix ternary lithium batteries with lithium iron phosphate batteries!