It is not recommended to mix the batteries with different degrees of old and new

When the same type of battery with different production dates is used together, the internal resistance test should be carried out first. The mixed use of the new and old battery with the same type is very harmful, which will cause the new battery to age in advance and shorten the service life seriously. Because of the different internal electrolyte, the corresponding internal resistance and voltage of different batteries will be different. When they are used in combination, if they are connected in series, it may lead to excessive discharge of batteries with small internal resistance and low potential, which will deplete the storage once, and generate internal current exceeding the allowable value, so as to age and discard them quickly. At this time, the new batteries in the battery pack will also be dragged down, resulting in a chain reaction.

If it is connected in parallel, the internal circulation of the battery will be generated. On the one hand, the external output will be weakened, on the other hand, the battery itself may be heated or even explode. Even in case of emergency use, do not mix batteries with different internal electrolytes. For example, it is very dangerous to use rechargeable battery and alkaline battery.