Acura RDX key fob battery

Separate remote fob

1. This remote is its own fob, separate from the metal key, which makes it one of the easier ones to open.
2. Turn it over: some older fobs use one small screw, newer ones just clip. Pry at the seam once any screw is out.
3. Replace the cell, keeping the + side where it was, and check the small metal tab still touches it.
4. Snap the case shut and watch for the lights to flash when you press lock at the car.

A CR1616 is 16 mm across and 1.6 mm thick. It is easy to confuse with the 20 mm CR20xx sizes, which will not fit.

Smart key (push-button start)

1. Find the small release on the edge or back of the fob and hold it while you pull out the metal emergency key.
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. Before you take the old cell out, look at its face. Put the new cell in with the same side showing, and avoid touching both faces at once.
4. Close the case until it clicks all the way round, put the metal key back, then try the buttons and a push-button start.

Acura smart keys usually open the same way as Honda's: release the built-in key, then twist in the slot.

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.