What battery names mean
Cylindrical lithium-ion cells are named by size. The first two digits are the diameter in millimeters, the next two are the length, and a final 0 means the cell is round. An 18650 cell is 18 mm wide and 65 mm long. A 16340 cell is 16 mm wide and 34 mm long.
Battery sizes in our lineup
| Cell | Size | Type | Nominal voltage |
|---|---|---|---|
| 18650 | 18 x 65 mm | Rechargeable lithium-ion | 3.6 to 3.7 V |
| 16340 | 16 x 34 mm | Rechargeable lithium-ion | 3.6 to 3.7 V |
| 18350 | 18 x 35 mm | Rechargeable lithium-ion | 3.6 to 3.7 V |
| 32650 | 32 x 65 mm | Rechargeable lithium cell | Check the product page |
| AAA | 10.5 x 44.5 mm | Alkaline or NiMH | 1.5 V alkaline, 1.2 V NiMH |
Each product page lists the exact cell and number of cells in its power source line.
Voltage and charge
A lithium-ion cell has a nominal voltage of 3.6 to 3.7 V and reads about 4.2 V when fully charged. Capacity is listed in mAh; a higher number means longer use between charges for the same cell size.
Some lasers use two cells in series, which doubles the voltage. That is why a power source line can read 2x16340 or 2x18350.
Case positive and case negative
Many metal lasers use the body as part of the electrical circuit. Case positive means the body connects to the battery's positive side. Case negative means it connects to the negative side. The power source line on each product page says which one applies.
Protected cells and button tops
A protected cell has a small circuit that cuts power if the cell is overcharged, drained too far, or shorted. The circuit adds a little length. A button top cell has a raised positive end, and a flat top cell does not. Whether a cell fits depends on the laser, so match the cell to the power source line on the product page.
Last updated 2026-11-01