Changing a watch battery is generally very straightforward and the following instructions and the two www.youtube.com videos at the bottom should make the whole thing very fast and easy. There are three main types of caseback as explained below. There is also a fourth type used by Traser and Luminox and a few MWC models and this is covered in one of the youtube videos.
CASE TYPE 1:
MILITARY WATCHES WITH A BATTERY HATCH E.G CWC, MARATHON, MWC ETC
Step 1
Lay the watch face down on a soft cloth and using a suitable coin gently turn the battery hatch anti clockwise and remove it.
Step 2
You will now be able to see the battery.
IMPORTANT:
Before removing battery(s), be sure to note which side is up. You will have to put the new battery in exactly the same way. In some watches, the battery is held in by small metal clips. If so, carefully follow the directions below for removing the various types of clips. Use plastic tweezers to remove battery(s).
Step 3
Once the new battery is installed check it is lined up properly before replacing the hatch. The hatch is replaced by turning it clockwise. Do not over tighten it should be screwed in until it is flush and offers a reasonable amount of resistance.
Reset the watch and make sure it is working. In analog watches, if there is no second hand, observe the minute hand through a magnifying glass until you see movement
CASE TYPE 2:
WATCHES WITH SNAP ON (PUSH ON) BACK
Step 1
If you have one place watch in the case holding vise. Clamp the watch in the case holding vise by opening the two halves of the block; ideally you should place a piece of leather or cloth between the watch and the vise to avoid scratches. Place watch in the middle and gently release or tighten the two halves, so that clamps will hold the watch firmly. If the watch band does not unbuckle or unclasp, separate the band by pressing down with a pointed tool to remove the spring loaded pin that connects the band to the clasp or watch. In the case of military watches with fixed pins this will be easier because they will have a one piece band.
If you don’t have a vice lay the watch on a piece of leather ideally or if not available a cloth but be careful of your fingers when opening the case.
Step 2
Most case backs are snapped on and can be removed by inserting a blade of a knife into the appropriate notch of the case or case back and a twist the handle of the knife to pop off the case back.
When no groove is provided, be sure a sharp knife is inserted into the narrow slot between the back and the case. Once the knife is firmly in the groove, a slight twist of the knife handle will pop off the back.
Twist the tool to snap off watch case back.
Step 3
IMPORTANT: Before removing battery(s), be sure to note which side is up. You will have to put the new battery in exactly the same way. In some watches, the battery is held in by small metal clips. If so, carefully follow the directions below for removing the various types of clips. Use plastic tweezers to remove battery(s).
SPRING CLIP: Lift up one end of the metal clip with the fine-point tweezers. It will come out. Then remove the battery.
Next test the battery - See the battery tester video at the bottom.
IMPORTANT: If the watch has two batteries and only one tests "replace", replace both batteries. If both batteries test "good", there is something wrong with the watch. In this case refer your local watchmaker.
Read the number on the old battery and replace with the same or corresponding watch Battery
Check the battery compartment for dirt and remove it. If you find corrosion, use a fiberglass pen to clean it, if the corrosion is extensive the watch will need professional cleaning refer watch to a professional watchmaker.
Be sure to test the new battery before installing. For tester setting, follow manufacturer’s instructions. Use plastic tweezers to install the new battery(s) with the same side up as the one(s) you replaced. Remember, the watch won’t work if the battery(s) are put in wrong.
SPRING CLIP: Place one end of spring clip in place and firmly push the other end into its slot. Make sure spring clip is in the slot to avoid bent spring clips.
SCREW-ON CLIP: Place the clip over the new battery. Hold the screw with the fine point tweezers to start it in the hole. Tighten the screw.
Step 4
If there is a rubber sealing gasket in the back of the watch, make sure it is lined up properly before closing back. Snap back cases are pressed either by hand or by a press to close.
Lastly, gently wipe the watch to remove any fingerprints or smudges.
Reset the watch and make sure it is working. In analog watches, if there is no second hand, observe the minute hand through a magnifying glass until you see movement.
CASE TYPE 3:
WATCHES WITH SCREW TYPE BACKS
Step 1
Place watch in the case holding vise. Clamp the watch in the case holding vise by opening the two halves of the block. Place the watch in the middle and gently release or tighten the two halves, so that they hold the watch firmly. If the watch band does not unbuckle or unclasp, separate the band by pressing down with a pointed tool to remove the spring loaded pin that connects the band to the clasp or watch.
Step 2
Locate the wrench slots on the back of the watch.
Place the Case Wrench metal tips in the watch back notches.
Turn counter-clockwise to remove watch back
IMPORTANT:
Before removing battery(s), be sure to note which side is up. You will have to put the new battery in exactly the same way. In some watches, the battery is held in by small metal clips. If so, carefully follow the directions below for removing the various types of clips. Use plastic tweezers to remove battery(s).
Step 3
Follow instructions in Step 3 above
Step 4
To close the back make sure it is lined up properly before closing. Start the back by turning it clockwise with your fingers, then tighten it with the Case Wrench.
Reset the watch and make sure it is working. In analog watches, if there is no second hand, observe the minute hand through a magnifying glass until you see movement
These two videos on www.youtube.com are both very helpful and informative: