Canon EOS R5 C User Manual page 733

2.
Attach the battery magazine.
Insert the battery magazine all the way in to secure it.
Caution
When attaching batteries, make sure the electrical contacts are clean. Wipe off any
dirt on the contacts with a soft cloth.
Attach batteries after attaching the battery grip to the camera. If the battery grip is
attached to the camera with batteries already attached, it may prevent correct
display of battery check results.
Before removing the battery grip, turn the camera off and remove the batteries.
Reattach the protective covers for the camera and battery grip contacts after
removing the battery grip. If the battery grip will not be used for some time, remove
the batteries.
If a battery communication error message is displayed when a battery grip is
attached, follow the instructions in the message. If the camera loses power,
reinstall the battery magazine and restart the camera.
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