Honda HR-V key fob battery

Key with remote in the head

1. This type has the buttons built into the key head. The cell is inside that head, between two clipped halves.
2. Work a thin flat tool into the seam near the blade and twist; go round slowly if it does not open at once.
3. Replace the cell with the same face showing, and make sure the rubber keypad sits flat before closing.
4. Snap it closed and press each button. The car still starts with a dead remote battery on most of these keys, because the start chip needs no battery.

A CR1620 is 16 mm across and 2.0 mm thick. It is easy to confuse with the 20 mm CR20xx sizes, which will not fit.

Smart key (push-button start)

1. Most push-button fobs hide a metal backup key. Press or slide its catch and draw the key out first.
2. Look inside the empty key slot for a notch. Put the tip of the metal key or a small flat screwdriver wrapped in tape there and twist gently until the shell splits.
3. Pop the old battery out with a toothpick or plastic pick, not a metal blade, and seat the new one with the + side matching the old one.
4. Reassemble, refit the emergency key, and check that the car sees the fob when you press start.

Honda smart keys typically have a release lever for the built-in key. Twist a coin or the key tip in the slot it exposes to split the case.

A CR2032 is 20 mm across and 3.2 mm thick. CR2032, CR2025 and CR2016 share the same width but not the same thickness, so a swap between them can leave a loose contact or a case that will not close.