Evaluating batteries for advanced wildlife telemetry tags

We evaluate miniature batteries as potential power sources for advanced wildlife telemetry tags. These tags are often based on integrated UHF transceivers that are designed for wireless sensor networks and that consume 18-85mA while receiving or transmitting. This current drain is challenging for many types of miniature batteries. We evaluate batteries both on actual tags and in a specialized synthetic-load circuit. Our evaluation focuses on the total amount of energy that the battery delivers until the tag fails, but we also investigate other important issues, such as the ability to withstand immersion in water. Our main findings are that zinc-air cells designed mainly for hearing aids perform extremely well in terms of effective energy density (but are hard to deploy), that lithium coin cells require a reservoir capacitor to deliver their rated energy (which is about half of that of zinc air with the same weight), and that rechargeable lithium polymer cells perform well even without a reservoir capacitor.