Shure Whiteboard - Rechargeables for Wireless

Shure UK Senior Applications Engineer, Tom Colman explores rechargeable battery options for wireless microphones - moving from standard disposable batteries to modern integrated rechargeables. Read the article below, or scroll down to watch the Whiteboard Video.

Wireless microphones and in-ear monitor systems all need power from somewhere. Traditionally, wireless operators use a standard portable cell in the form of familiar alkaline dry cell batteries. They might not be great for the environment, but they are easy to obtain and very reliable. It's only relatively recently that explorations into rechargeable options for wireless systems have met the standards required for professional use. More on this later, but let's first look at the historic standard:
 

Standard Batteries

Alkaline batteries will discharge at a very linear rate, meaning power will reduce evenly throughout the life of the battery. So let's say we have a fully charged battery with five indicator bars. In the case of alkaline disposable batteries, power will discharge at the same pace when at bar five or bar one.
 

In the case of standard consumer rechargeable batteries, the battery performance is much less predictable. The discharge rate is not linear and is likely to reduce faster towards the end of the battery cycle. This unpredictability makes standard consumer rechargeable batteries unsuitable for professional productions.
 

Lithium Ion Rechargeable Batteries

Knowing the historic issues with rechargeable technology, we (Shure) set out to develop a reliable rechargeable system for the professional audio industry during the development of our high-end Axient wireless system. The result was an advanced power management system — based on medical-grade Lithion Ion cells — that introduced real-time monitoring and lifecycle management to batteries and chargers. Since the launch of Axient around five years ago, much of this advanced wireless technology is now available (where possible) across the Shure portfolio of wireless systems.

Taking Axient as the example, these purpose-built, modern rechargeable systems give us far more reliable performance and essential data to help ensure peace of mind. Utilising a built-in microchip, the Axient system is able to deliver real-time readings of various key data-points:
 

• Battery Health - The overall capacity of our battery compared to when it was new.
• The current charge (measured in 1% increments)
• Cycle Counts: This represents the amount of times our battery has completed a full cycle from 100% down to 0% and back up to 100%. This reading is cumulative, meaning it could also represent a cycle of 100% down to 90% repeated ten times. It's estimated that when a battery has completed 500 cycles it will still have a battery health reading of around 80%. That's a lot of AA batteries saved from landfill!

By using a microchip in each battery, we know exactly how much capacity is remaining through a real-time reading in hours and minutes. This reading is accurate to within 15 minutes, and therefore, if your battery is showing 1-hour remaining and the event is 30 minutes long, you can be confident the battery will last for the duration.