Mercury-free: Hearing aid batteries are going green

Mercury free hearing aids batteryWHEN:  June 30, 2011.  Today is the day.  Manufacturers of hearing aid batteries can no longer sell or distribute “button cell” batteries that contain mercury, including zinc air hearing aid batteries.

SAYS WHO?  In May 1996, President Clinton signed The Mercury-Containing and Rechargeable Battery Act.  The act stipulates two main points:

Title I: To facilitate the recycling of nickel-cadmium and some types of small lead-acid rechargeable batteries

Title II: To phase out the use of mercury in batteries

Button cells initially were exempt for a few reasons including the technology to create a mercury-free design was not available.  As a result, the industry negotiated the June 2011 deadline for compliance with the new act.

HOW THEY WORK:  Zinc air hearing aid batteries use the zinc as a “fuel,” which is activated by oxygen from the air, after you pull the tab off the back.  These batteries have a high capacity and a flat discharge profile – meaning they’re strong enough to power a high-energy device like a hearing aid while maintaining constant power so that sounds don’t get weaker as the battery is used.
WHY CHANGE?  Generally, zinc air hearing aid batteries are considered environmentally friendly.  The amount of added zinc in each battery is only about 1% by cell weight.  Also, the tiny holes on the flat (positive) side of the battery are vents that allow gasses to escape, suppressing cell rupture or explosion.  However, the concern about zinc seeping into the ground or water supplies as the batteries decay is not completely eliminated.

WHAT THIS MEANS FOR YOU:  Hearing aid battery manufacturers are in various stages of research to develop the best formulations for a reliable, long-lasting mercury-free battery.  Rayovac©, one brand we use at SWENT, has released its second generation of mercury-free batteries.  At this time, it appears that the environmentally friendly cells are not quite comparable to their mercury counterparts.

A few things you may notice when you start using mercury-free batteries:

1)      Mercury-free batteries may not last as long as the mercury version.  Expect them to last about one day less, give or take.

2)      It may take more time for the battery to activate after you remove the tab, so wait an additional 10 seconds to let the battery “breathe.”

The good news is that as technology improves, the battery reliability will continue to improve.  In the meantime, we can enjoy knowing that we’re moving a step closer to environmental sustainability.  The next time you’re shopping for batteries, look for the “mercury-free” labeling on the packages.  Some are even boxed in recycled materials.