Replace the batteries without changing the chemistry
The compartment is on the interior frame’s top edge. Press down the cover, slide it in the arrow’s direction, remove the old cells and insert 4 new alkaline batteries: C-cell for Medium or D-cell for Large. Slide the cover back into place.
PetSafe explicitly prohibits lithium and rechargeable batteries. This is a stated restriction, not merely an omitted recommendation.
PetSafe · www.petsafe.comPetSafe Support · support.petsafe.net
Read the light after replacement
The battery instructions describe blue-blinking Wi-Fi while a previously configured door reconnects. Yellow flashing means it has not been connected to Wi-Fi before. These states describe the connection, not a need to try another battery chemistry.
Choosing the adapter is a different purchase
The named SmartDoor power adapter is supported for both door sizes. Check the accessory identity in the listing rather than comparing connector appearance alone. The confirmed relationship applies to that accessory; it is not a general third-party power-supply approval.
An alert and an unpowered door lead to different support topics
My PetSafe reports battery status. A battery notification is a reason to inspect the corresponding power information; a door with no power belongs in the no-power support procedure. PetSafe also separates cleaning and maintenance from those power tasks.
The cited PetSafe instructions do not set a fixed replacement interval. Prepare the correct supply, retain the alert or observed symptom, and follow the matching official procedure. If that does not explain the problem, contact PetSafe rather than improvising an electrical repair.
PetSafe · www.petsafe.comPetSafe Support · support.petsafe.net
FAQ
SmartDoor Connected Pet Door frequently asked questions
Each answer stays within the facts and sources shown on this page.
01Can I substitute lithium or rechargeable cells when replacing the batteries?
No. PetSafe’s battery instructions explicitly prohibit lithium and rechargeable batteries and specify alkaline cells. Use 4 C-cell batteries for Medium or 4 D-cell batteries for Large.
02Is the optional SmartDoor adapter restricted to the Large door?
No. PetSafe documents the optional SmartDoor power adapter for both Medium and Large. This does not confirm an arbitrary third-party adapter.