I put two common and two alkaline batteries in a flashlight I own. What kind of trouble can this lead to the flashlight?
In fact, for the flashlight we will have no problems to consider unless it will not work properly. Common (dry) batteries have lower durability and lower current capacity and therefore have greater internal resistance than alkaline or rechargeable batteries. This means that, before running out, the alkaline batteries reduce the current in the supplied circuit even before the alkaline ones are weakened. In other words, the power will be "leveled down" with the unit no longer functioning when the lower capacity batteries become weak. On more sensitive devices this difference in current supply can also affect performance, hence this practice is not advisable. The same applies when we mix batteries, even of the same type, but have already been used for different times. Those weaker ones, when they are exhausted, will affect the performance of the others.
