Replace the set together
Cells in a series pack carry the same current. A weak cell can be driven into damaging conditions by stronger cells.
Keep type and make consistent
Different chemistry, age, capacity and internal resistance create uneven behavior even when every cell says AA or AAA.
Check orientation
Install every cell using the device polarity marks. A reversed cell can be charged by the rest of the pack.
Decision boundary
This guide narrows a battery decision but does not override the device manufacturer’s current manual or safety instructions.
Sources
- Energizer — Battery Replacement Guide
Cross-reference codes and manufacturer guidance to replace the same size and type together.
- Duracell — Battery chemistry technical bulletins
Alkaline, lithium-manganese-dioxide, zinc-air and silver-oxide chemistry behavior.