The topic of batteries would seem to be a fairly simple subject. I purchased some tactical flashlights that use a more specialized battery and I wanted to see if I could use a rechargeable battery. This seems like a pretty simple question. What I found was a very confusing and complicated battery landscape. Here are some of the more common batteries:
| AA | 1.5v | Smaller devices including camera strobes, flashlights, etc. |
| AAA | 1.5v | Smaller devices including headlamps, flashlights, etc. |
| CR123 | 3v | Used in most tactical, high-powered flashlights. |
| RCR123 | 3.7v | Rechargeable version of the CR123. These normally output a higher voltage and I do NOT recommend using these batteries in flashlights that were not designed to use them. The higher voltage could damage your flashlight. |
| C & D | 1.5v | Used in larger flashlights, lanterns, etc. |
These are standard batteries and things get complicated after this.
| Type | Composition | Voltage | Size | mAHr | Comments |
| AA | Alkaline (d) | 1.5v | |||
| Alkaline (r) | 1.5v | ||||
| NiCad (r) | 1.2v | ||||
| NiM (r) | 1.5v | ||||
| CR123 | Lithium (r) | 3.0v | 0.64″ x 1.3″ | 1400 | |
| RCR123 | LiFePO4 (r) | 3.7v | 0.64″ x 1.3″ | An ICR battery includes circuit that makes the battery appear as a 3v cell. | |
| 16340 | Lithium (r) | 4.2v max 3.7v nominal |
0.71″ x 1.3″ | 550-700 | Similar to CR123 but slightly larger diameter. |
| 16340 | LiFePO4 (r) | v | Similar to RCR123s and uses safer chemistry but outputs lower voltage. | ||
| 18650 | (r) | 3.6v – 3.7v | 69.2mm x 18.4mm | Looks similar to a large AA battery and used in a number of rechargeable tactical flashlights. | |
| ICR & IMR | (r) | 4.2v max 3.7v nominal |
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| IFR | LiFePO4 (r) | 3.6v max 3.2v nominal |
