After two and a half years my key fob battery needed replacement. It still worked but there was a message on the dash whenever I started the car telling me that it needed to be replaced
I drove it for a few days with this message, but I didn't want to push my luck so I used my spare fob for a few days until I had a chance to replace the battery.
The owners manual has fairly adequate instructions about replacing the battery:
Yes it's pretty simple, but these fobs are expensive and I wanted a better idea what to expect when I took the fob apart to avoid accidentally damaging it. I looked online and I found some general YouTube videos for Honda key fob battery replacement and that gave me a better picture. After changing my battery I decided to post some photos and my experiences to help anyone who might be hesitant to do it themselves.
You will need a new CR2032 battery, two of them if you will be changing batteries in both fobs at the same time. These type of batteries have a long shelf life so you can save some money by buying a multipack.
You will also need a small screwdriver to pry out the battery.
The first step is to remove the emergency key by sliding the little switch to the right.
As a side note, as probably most people know the emergency key is used to open the driver door in case your 12V battery is dead. But it also can be used to open the trunk using the lock behind the driver side rear passenger headrest. Good to know this when your 12V battery is dead and your portable jump starter is stuck in the trunk!
After removing the emergency key, the instructions say to use a coin to split the fob into halves. And to wrap a cloth over the coin to avoid scratching the fob (???)
It's not as clear in the instructions but what you do is insert the coin between the tabs that stick out, as highlighted with the yellow arrow in the photo below. The 2D photo doesn't really show the tabs very well, it's easier to see what I am talking about if you pull out the emergency key on your fob and take a look at these tabs.
Something I found online pointed out that instead of a coin you can use the emergency key. In fact the key fits perfectly between the tabs, so clearly it was designed this way. I doubt if it harms the key as it didn't take that much force to open the fob. But if you are worried about using the key go ahead and use a coin (and be sure to wrap the coin with a cloth LOL)
After splitting the halves you now have access to the CR2032 battery.
The instructions say to "Remove carefully to avoid losing the buttons". That's kind of an odd statement. I found out what this actually means is that when you are digging around with a small screwdriver trying to pry the battery out, it's pretty easy to accidentally start pulling out the circuit board that the battery is connected to, because the circuit board is not attached to anything. The buttons are connected to the other side of the circuit board, so if you accidentally lift the circuit board it starts to pull the buttons out of their holes. I guess that's what they mean by "losing the buttons", maybe the buttons will fall off the circuit board if they are completely pulled out of the fob.
To avoid this, instead of holding the fob in your hand while removing the battery, which is what I tried to do at first, instead keep the fob laying flat on a table while you are removing the battery. That way you can hold the fob against the table with one hand while you use your other hand to pry out the battery with the small screwdriver. This helps hold the circuit board in place and keeps it from lifting up out of the fob when you pry upwards with the screwdriver.
As seen in the next photo the yellow arrows are pointing to two tabs that overlap the battery. The green arrow shows the best place to insert a small screwdriver under the battery and pop it out. Pretty simple and straightforward, but I prefer to take this step slowly considering how much a replacement fob costs.
After removing the old battery, insert the new battery first under the two tabs highlighted by the yellow arrows, then press down and it should easily pop into place past the two smaller tabs on the other side (the two tabs closest to the green arrow in the photo.
Getting the two halves to snap back together took more pressure than I expected which made me a little nervous. I wondered if maybe I didn't have it aligned correctly, and I was worried about breaking the locking tabs if I pressed too hard. But it seemed to be aligned, and with enough pressure the two halves snapped back together. But I found a better way to do this when I changed the battery on the second fob. After getting the two halves exactly aligned, I squeezed first on the "top" end of the fob, the end on the opposite side of where the emergency key goes. When that half came together, I then squeezed the end of the fob where the emergency key goes, and the two halves snapped together with much less pressure this time.
As another side note, the outside of my fob was starting to get scratched up (as you probably noticed in the first photo) so I bought a cover for it on Amazon, you can search for Coolbestda Silicone 6buttons Smart Key Fob Remote. You get two of them for $11.00