This is a repost from January of 2005.
A little bit of research into button batteries for Deben locator collars has convinced me that we rarely get what we pay for, especially if we are buying our batteries at CVS, Home Depot or Radio Shack.
As always, it's important to NEVER use a zinc-air battery. Having said that, there are a lot of other options which are mechanically interchangeable: Duracell D375H or D393; Panasonic SR44W or SP357 or ST48W or SP393; Ray-O-Vac RW42 or RW48; or an Ever Ready BSR 44H or BSR 48H or BSR 48L or any button battery labeled "AG-13".
Setting aside brands and numbers, all of these batteries look alike, but not all are alike chemically. Two different chemical compositions are commonly offered -- silver oxide and alkaline.
What's the difference? For our purposes, not much. Silver oxide batteries will last 15% to 35% longer than alkaline batteries, but they cost so much more that they are simply not worth it. In addition, silver oxide batteries tend to lose power over time and do not operate as well in cold temperatures.
Rather than spend money on expensive silver oxide batteries, a better investment is a $5 button battery tester. A battery tester will tell you the one thing you really need to know, which is whether the battery you are about to put in a collar is putting out enough juice to pump a signal 15 feet up to the receiver box. Brand and chemistry matters much less than the charge in the battery at the moment.
Retail prices for batteries are phenomenal. A 1-pack of the silver oxide Energize 357 model is $3.19 from Radio Shack, and alkaline batteries are about $2 apiece in most stores.
If you hunt very much, the lowest cost solution is to avoid retail purchase of button batteries and instead buy a lot of Chinese-made ("Everrich") alkaline batteries which are commonly sold on Ebay for about 15 cents each (100 batteries for $15). Just go to www.ebay.com and type in "button battery 44" or "button battery AG-13" and look for a "Buy It Now" button.
Always test batteries before you put them in a collar, tape the collars over breakfast (rushed taping in the field often leads to problems), and you will avoid a lot of troubles.