How long will a new battery keep?

Most rechargeable batteries should be used 5-7 years from manufacture date and should be stored in a cool, dry environment (not the fridge! That's an urban myth). My question is, will you need these batteries in a couple years, or will you have switched phones by then?

 

A lot of people love ths Sony Z models. They still are considered some of the best phones ever to come out for Sprint. My mom used to have the one where the earpiece slid up to answer the call. It was an odd design to say the least, but the thing worked great. Only Sanyos can beat the old Sonys on Sprint, IMO.

 

I liked the ones with the boom mic that extended. A friend of mine had the earpiece one with Verizon. I thought it was a nice way to enable a keyguard.

I know that you are reluctant to change phones, but once you get voice dial, you will never go back No matter how nice a phone is, without voice dial it's only an expensive paperweight.

 

What chemistry is it?

If it's NiMH, you can just toss in box and put it away without a thought.

Lithium ion battery doesn't have a great shelf life and they will deteriorate whether they're used or not. Deterioration(permanent partial loss of cell capacity) starts as soon as it's rolled out of factory like a medication with expiration date.

My Motorola manual recommends storing spare Li-ion batteries discharged, in the refrigerator.

I don't know about the effectiveness of refrigerated storage of Li-ion batteries. For whoever suggested it's a myth, the discussion you're thinking doesn't include lithium ion chemistry.

The only thing not to do is store them fully charged. Even though rate of discharge is slow, it can be permanent. Fully charged battery suffers irreversible capacity loss faster than partially charged or discharged battery.