Maglite flashlights come in a variety of sizes, usually sized by the battery requirements. They can range from one AAA battery model to a burly six D-cell battery model. All Maglites follow similar protocols when replacing the batteries, although sometimes access is denied to the battery compartment because of corroded or leaky batteries. Should this occur, you might qualify for a free replacement. Otherwise, battery replacement takes only a few moments of your time.
Hold the flashlight with the lens pointed down and grab the back tail cap with your other hand.
Rotate the tail cap counterclockwise until it screws off completely. If the tail cap will not twist off, it is likely caused by leaky or corroded batteries. If this is the case and you used Duracell, Eveready or Ray-O-Vac batteries, Mag Instrument Inc. will replace the flashlight for you for free. Just send your Maglite to Mag Instrument Inc., Attn; Warranty Dept, 1721 E. Locust St., Ontario, Ca 91761-7769.
Turn the flashlight upside to allow the batteries to drop out, preferably in a bag to contain any battery leaks. You may need to shake the Maglite to encourage the batteries to drop out.
Insert the new batteries in the same direction the old ones were installed. This should be with all the positive ends of the batteries in a single line, pointed toward the lens.
Replace the tail cap and tighten by twisting it in a clockwise direction.