I just got a new car with two intelligent key remotes. Manual says to use a cr2025 and I happen to have a huge numberof cr2016 batteries. They don't appear to be the same size exactly but was wondering if they are interchangeable?
IIRC how to decode the number, (posted here somewhere,) the battery you have is 20mm diameter and 1.6mm thick. You need 20mm diameter and 2.5mm thick. I think they are otherwise the same.
So in an emergency you should be able to use your 2016 if you can shim it up to fit and make contact. (You will have less capacity and may be subject to shifting and shorting out. I wouldn't do it as a normal practice. If you have a Fry's you should be able to get them in store and several of the CPF vendors carry them.)
I suppose I would rather have the correct battery, question is who makes a long lasting initial charge battery, saving a bit isn't important, I did some searches but didn't come up with anything. It doesn't do any good to buy back up batteries that are dead when put to use.
For something so cheap (and so important) i wouldnt mess around. Like you i had lots of a similar sized battery to the ones my key uses but i err on the side of caution and picked up some ofthe correct size. When i first bought the car i changed out both batteries (everyday key and spare). Make a note of the date and change these on a regular basis, maybe every 6 months or once a year. Personally i change once a year, id much rather spend a bit extra and throw away a good battery than have a battery run out when im a long way from my spare key!