The Hyundai owner’s manuals listed here give a CR2032 for the remote key, and a CR2032 or a CR2450 for the smart key by model and year: the 2025 Palisade’s smart key takes a CR2032, the 2025 Tucson’s a CR2450.
The battery it takes
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Hyundai key batteries by model
| Model and key | Battery |
|---|---|
| 2025 Tucson, smart key (push-button start) | CR2450 |
| 2025 Tucson, remote key (buttons on a key with a blade) | CR2032 |
| 2022 Tucson | CR2032 |
| 2024 Santa Fe | CR2450 |
| 2019 Santa Fe | CR2032 |
| 2024 Sonata | CR2450 |
| 2021 Sonata | CR2032 |
| 2027 Palisade | CR2450 |
| 2025 Palisade | CR2032 |
| 2023 Palisade | CR2032 |
| 2026 Kona | CR2450 |
| 2019 Kona | CR2032 |
| 2021 Elantra | CR2032 |
| 2026 IONIQ 9 | CR2450 |
A model listed once has the same battery in its remote key and smart key, or a smart key only, in its manual.
How to change the smart key battery
From Hyundai’s 2025 Tucson manual:
- Take out the mechanical key.
- Put a slim tool into the slot and gently open the rear cover.
- Take out the old battery and put the new one in, making sure it’s the right way round. Hyundai warns that a battery in the wrong position may discharge and make the smart key fail.
- Put the rear cover back on.
For the remote key, the 2025 Palisade manual says to pry the cover open with a slim tool at the slot, then take off the battery cover with a screwdriver.
If the smart key stops working
Hyundai’s 2025 Tucson manual says to lock and unlock the door with the mechanical key, and to start the engine by pressing the Engine Start/Stop button directly with the smart key. The 2025 Palisade manual adds to hold the key against the button the way its picture shows.
Keep coin batteries away from children
Hyundai’s 2025 Tucson manual warns that a swallowed lithium button battery can cause severe or fatal injuries within 2 hours, and to keep batteries out of children’s reach.
The National Capital Poison Center says that if anyone swallows a battery, immediately call the 24-hour National Battery Ingestion Hotline at 1-800-498-8666 or your poison center at 1-800-222-1222. Don’t delay. Immediate treatment decreases severity.