Canon EOS 5D Mark III Instruction Manual page 346

3 Checking the Battery Information
Labeling the Serial No. on the Battery
Affixing a serial number label onto all the registered Battery Pack LP-
E6's makes it convenient.
Serial No.
Do not affix the label on any part other than as shown in the illustration in
step 2. Otherwise, the misplaced label may make it difficult to insert the
battery or impossible to turn on the camera.
If you use Battery Grip BG-E11, the label may peel off as you repeatedly
insert and remove the battery pack. If it peels off, affix a new label.
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Write the serial number on a
1
label.
Write the serial number displayed on
the battery history screen on a
commercially-available label approx.
25 mm x 15 mm / 1.0 in. x 0.6 in. in
size.
Take out the battery and affix the
2
label.
Set the power switch to <2>.
Open the battery compartment cover
and remove the battery.
Affix the label as shown (side with no
electrical contacts) in the illustration.
Repeat this procedure for all of your
battery packs so you can easily see
the serial number.