YOU CAN REPLACE BATTERY in Non CA keys!!!!
 

Alot easier than you might think dealer and even good Indy mechanics will tell you it cannot be done, I do it at $50 a pop for friends and people who dont want to buy another key you just need an EXACTO knife and a glue gun and you basically separate the front of the key from the back of the key pop in a new Watch battery CR 2025 I think and glue gun it back together NEATLY!!!
looks good as new just saved yourself a fortune. Good luck and cut carefully dont hit the circuit board too hard or you might cut off a transistor :-)
*This is for informational purposes only, I am not responsible for any keys that dont work if tampered with*:dunno:

Yes it can be done

So you replace a rechargeable battery with a non-rechargeable one and that does not cause any issues when you use the key? To me that sounds like a bad idea. If you replace it with a rechargeable then I am sure you can do it then

REPLACING BATTERY IN NON CA KEYS
 

I wasnt going to elaborate too much on this because I dont want readers blaming me if it doesnt work or they break their keys, I figure if your at the stage of considering it then your about to spend $200 on a new key anyways and that old one will just be a backup.
Ok kids, yes the factory key is a rechargeable watch battery, I use a Li-Ion 3V replacement Duracell, Energizer etc.. I am assuming due to lack of any complaints from keys I have done that the battery has a long life 3V is actually pretty powerful for what the power draw from the key is. I dont know how long they will last maybe a 1 year to a few years there are 2 pieces of metal soldered to the factory battery + and - sides that you have to break and re attach to the new battery, but you have to break it carefully from the old battery dont break it into pieces! The hardest part really is just cutting the plastic with a very sharp razor, slowly scrape away at the seam all the way around the key other than that its pretty straight forward make sure you put the new batter exactly the same way the old one was with those metal plates facing the exact same way as before, take a picture with your phone before you start breaking things :stickpoke
Good luck I just save you all hundreds of dollars please send all donations to me!:rofl:
Or Pm me if you really dont want to do it, other than that dont forget to RE INITIALIZE YOUR KEY TADA:popcorn:

I just did a little research and according to SONY the power draw of the keyless entry systems is similar to that of a PC motherboard so lifespan will vary but could be several years, Im guessing the amount of recharge the cars ignition provides is minimal at best so perhaps that drip charge is possible with all coin batteries, pure speculation on my part havent confirmed anything, maybe someone in here with a more technical background can get down to the details and figure it all out.