Can old and new batteries be mixed or charged together?

Due to the relatively low internal resistance of new batteries, while the internal resistance of old batteries increases to varying degrees, when new and old batteries are mixed together for charging, the high internal resistance of old batteries can easily lead to excessive voltage division, which can easily cause overvoltage charging; For new batteries, the internal resistance is small, the charging voltage is low but the current is high, and it is easy to cause overcurrent phenomenon. Therefore, mixed charging of old and new batteries should be avoided during the charging and discharging process.