Six months ago, the battery in my 2010 Mazda 3’s key fob (aka “flip-key”) totally died and I needed to replace it. The battery in these things is a CR1620, which I couldn’t find anywhere in stores, so I ordered the cheapest ones I could find off eBay — a pack of 3 generic brand Eunicell (made in China) for $2.18 CAD shipped. Unfortunately, I didn’t have a good first experience with them. There’s an orange LED on the key fob that should light up whenever you press a button. On a working key fob that still contained the original Panasonic battery from the manufacturer, the LED glowed brightly and solidly, but on the one where I had just replaced the battery with the Eunicell, it was flickering and dim. I actually couldn’t get the first battery to work, so I had to take a 2nd one from the 3-pack, and that eventually did work, but never 100% reliably. I also had to reprogram the key fob to be recognized by my car. I concluded that these batteries were just “weak” or underpowered, or that the eBay seller was giving me old/used stock (I now realize that this wasn’t true). Anyway, a week ago, I sought out a brand name and ordered a 5-pack of Sony batteries (made in Japan) from Amazon, which cost me $13 all in (including Ontario taxes).
Funny enough, today while I had the key disassembled and was about to replace the Eunicell battery with a Sony, I thought back to the time when I fixed a broken mouse button by simply cleaning the electrical contacts. In my Mazda’s key fob, there are two silver-coloured metallic prongs which contact the battery on the opposite half of the fob. I couldn’t see any visible dirt on these contacts, but I could feel a bit of grime on it, so I just scratched it off with my fingernails until it felt smooth. Sure enough, this fixed it, and the key worked right away! Each button press now produced a solid orange light, and this is with the same Eunicell battery that I had written off before. I didn’t even have to reprogram it this time. I guess the cheap stuff from eBay isn’t so bad after all. Wish I had thought of this before spending the money on new ones, but oh well. Anyone need 5 new, unopened Sony CR1620 batteries? 😛
- The Eunicell branded battery is several times cheaper and works perfectly fine.
- Cleaning electrical contacts can work wonders. It’s a free fix and works for all kinds of stuff like computer mice, batteries for small electronics, and even a Toyota Prius…
Oh, and just in case someone came here expecting a how to guide, here are the links that I found most helpful:
- Video guide: How To Replace A Battery In A Mazda Key Fob [youtube.com]
- Text with pictures: How to: Replace flip key battery [mazda3forums.com]
- Reprogramming guide: Spare Keyless Remote Self-Programming – How To Guide [mazda3forums.com]