1The Emergence of Silver-Zinc Rechargeable Technology Within Hearing Aids Reprinted from Innovations: Volume 4, Issue 1, 2014

The Coming of Age of the Rechargeable Hearing Aid Battery

In a technological world that demands plug-and-play functionality, the ability to “charge and go” has become a non-negotiable feature requirement. Consumers demand this from modern electronics such as cell phones, tablets and MP3 players. For hearing instrument users, rechargeable batteries now have the potential to replace the established practice of disposable battery technology, thus including hearing instruments within the realm of plug-and-play functionality.

Since the early 1970s, rechargeable hearing aids and hearing aid batteries have been available in one form or another. Now, some forty years later, we are still holding on to our conventional zinc-air batteries, as the market for rechargeable hearing aids and batteries hasn’t responded to the inconvenient and expensive rechargeable technology that has been made available up until now.

MarkeTrak data consistently shows patients are either dissatisfied with the battery life of their hearing aids or are seeking a device with rechargeable batteries (Kochkin, 2002; 2012). Furthermore, focus groups involving Starkey Hearing Technologies research participants highlight how frequently patients report the desire for a rechargeable option. In fact, results from our focus groups and results obtained through an independent consulting firm demonstrate that a battery charging function is one of the most highly rated features among hearing instrument patients and professionals. In addition, feedback from such aforementioned focus groups provides insight on

the development of hearing aid rechargeable battery requirements. Specifically, these development requirements include the following:

1. Hearing aids must be able to use conventional zinc-air or rechargeable batteries.

2. Patients must be able to replace the rechargeable battery without sending the aid in for replacement.

3. Rechargeable batteries must operate in a hearing aid for at least 15–18 hours a day.

4. Rechargeable batteries must provide sufficient energy capacity to support advanced hearing aid functions.

5. Rechargeable batteries must provide a green alternative to existing technologies.

Rechargeable Batteries Are the Green Alternative

Compared to conventional battery technology, rechargeable options reduce waste because consumers don’t need to replace their batteries nearly as often as they do with conventional batteries. In addition, reducing the amount of battery packaging helps prevent the growth of waste into our landfills. Another key advantage of rechargeable hearing aid batteries is that they do not contain mercury by-products, making disposal clean and safe while promoting recycling efforts. Therefore, the use of rechargeable batteries is consistent with green technology and a step toward keeping our planet clean.

THE EMERGENCE OF SILVER-ZINC RECHARGEABLE TECHNOLOGY WITHIN HEARING AIDSJohn Ellison, M.S., & Mary MacRae

2 3The Emergence of Silver-Zinc Rechargeable Technology Within Hearing Aids Reprinted from Innovations: Volume 4, Issue 1, 2014 The Emergence of Silver-Zinc Rechargeable Technology Within Hearing Aids Reprinted from Innovations: Volume 4, Issue 1, 2014

Why green? Being “green” is not only valuable to the community but also to our primary customer population. A marketing communications company collected more than 6,000 consumer responses on household products that showed that older consumers are more likely to use green products than their younger counterparts (ICOM, 2008). Specifically, females between the ages of 55 and 59 years old were most likely to use green products and were more than twice as likely to use such products compared to the average consumer. Adult men between the ages of 65 and 69 years old were the second most likely demographic to use green products and were nearly twice as likely to use green products than average consumers.

The User Requirements for Using Rechargeable Batteries

If a good portion of our target demographic is interested in an environmentally friendly battery, why hasn’t the rechargeable option caught on? This is likely the result of rechargeable hearing instruments either failing to meet the demands of the consumer and/or not performing as well as conventional technologies. Hearing aids with rechargeable batteries often require patients to send the devices in to the manufacturer for battery replacement. This requires the patient to use backup devices, which are an inconvenience for the patient and the hearing healthcare professional alike. Furthermore, in devices that seal the rechargeable batteries into the hearing aid casing, rechargeable batteries cannot be swapped with conventional batteries in the event of a battery failure. This leaves the patient with one of two less-than-ideal options: 1) use backup devices or 2) go without amplification. Our patients agree that these options must be overcome for rechargeable technology to gain traction. In fact, 95 percent of study participants that we polled responded that it was important to be able to replace their rechargeable batteries with conventional batteries (Ellison, 2011).

Another limitation of hearing aid rechargeable battery technology and a potential reason why rechargeable batteries in hearing aids have not caught on lies in the size of the battery. To start, hearing aids are getting smaller. In addition, hearing aid processing is getting more sophisticated and complex, which increases the demand for battery power supply. This means we need to fit more powerful batteries in tinier spaces. However, this is constrained by the fact that smaller batteries typically have shorter operating times. This constraint is emphasized by the vast majority of Starkey Hearing Technologies research participants preferring rechargeable batteries only if they operate throughout the entire day (Ellison, 2011).

The introduction of nickel metal hydride (NiMH) batteries allowed the development of batteries with the required power and size for consumer use. Currently, NiMH batteries are the only type of rechargeable battery used in hearing aids. NiMH batteries are capable of achieving 15–18 hours of wear time and supplying enough power as long as the hearing aid current drain is limited. However, restricting the current drain also limits the processing power that is required for the function of the advanced features common in modern hearing aids. NiMH batteries have a low self-discharge rate, which ensures sufficient shelf life. Professionals are able to buy in bulk and store the batteries. Furthermore, the discharge cycle is stable and predictable. Unpredictable discharge cycles can negatively influence the hearing aid response characteristics and ultimately result in poor acceptance of the hearing aid by consumers. In sum, NiMH rechargeable batteries meet many of the requirements necessary for use in hearing aids. However, improvements are on the horizon.

Starkey Hearing Technologies’ New Rechargeable Battery Offering

Starkey Hearing Technologies’ rechargeable silver-zinc (AgZn) batteries, which no other hearing aid manufacturer currently uses, offer several important improvements over NiMH batteries (Table 1). Specifically, AgZn rechargeable batteries operate with a higher capacity and greater energy density than NiMH batteries, resulting in longer daily battery life for a fixed volume (Figure 1). This allows for the ability to match NiMH performance in a smaller casing. Therefore, these have a greater potential for achieving required battery performance in smaller hearing aids. This also allows AgZn batteries to support the higher current drain necessary for the increasing number of complex and advanced hearing aid features. In addition, use of AgZn has a lower self-discharge rate, allowing for longer storage, as well as allowing the professional to buy batteries in bulk, reducing battery purchase costs.

Starkey Hearing Technologies’ rechargeable battery technology is designed to meet the needs of the hearing aid user and the associated five development requirements specified above. The specifications for our rechargeable batteries are the following:

1. Hearing aid users can substitute conventional batteries in the event that they lose or damage rechargeable batteries.

2. There is no need to send the hearing aid in to the manufacturer for replacement or repair, which also eliminates the need for a backup hearing device.

3. Starkey Hearing Technologies AgZn technology can operate for the required 15–18 hours a day.

4. The AgZn technology supports advanced hearing aid features.

5. Rechargeable batteries offer a greener solution than conventional disposable technologies.

Starkey Hearing Technologies’ solution allows consumers to use a streamlined spare battery charger, which securely locks the batteries in place and automatically determines the polarity of the batteries (Figure 2). It efficiently determines the charge state of the batteries to provide the appropriate charge, and it activates LED indicators to notify the user when charging is complete. The spare cell charger can plug into a standard wall outlet, computer or optional car adaptor, and it is small enough to carry in a purse or pocket, which makes it convenient and travel friendly.

SIZE 13 BATTERY NiMH AgZnVoltage (V) 1.2 1.6

Typical Capacity (mAh) 30 32-35

Energy Capacity (mWh) 36 51-60

Operating Time/Charge (hrs)* 16.7-30 17.8-30

Self-Discharge Rate/Month < 20% < 5%

SIZE 312 BATTERY NiMH AgZn

Voltage (V) 1.2 1.6

Typical Capacity (mAh) 22 28

Energy Capacity (mWh) 26 45-47

Operating Time/Charge (hrs)** 13.8-15 17.5-30

Self-Discharge Rate/Month < 20% < 5%

Table 1: Comparisons across nickel-metal hydride and silver-zinc rechargeable batteries

* 1.8 mA average drain ** 1.6 mA average drain

NiMH13 & 312

300

250

200

150

100

50

0

AgZn 13 AgZn 312

Wh/

I

Energy Density

Figure 1: Energy density in watt hours per liter (Wh/l) for NiMH and AgZn rechargeable batteries. The NiMH is plotted as one bar because of the close proximity of the energy density for both size 13 and size 312 batteries.

4 The Emergence of Silver-Zinc Rechargeable Technology Within Hearing Aids Reprinted from Innovations: Volume 4, Issue 1, 2014

Many of Starkey Hearing Technologies’ non-wireless devices support the use of AgZn rechargeable batteries. Devices currently in the field can also use rechargeable batteries with a simple update through the Inspire® fitting software. See Table 2 for a complete list of supported Starkey Hearing Technologies hearing instruments. As with any emerging technology, we see immediate benefits for many consumers but expect continued improvements and broader applications as the technology is refined. Currently, the peak power capability of the AgZn is not sufficient to support wireless hearing aids in streaming modes and are not recommended for use in those products.

Conclusion

Starkey Hearing Technologies has introduced a rechargeable option that not only minimizes the limitation of earlier rechargeable options but also raises the bar by allowing users to recharge with a small, travel-friendly charger. Finally, Starkey Hearing Technologies hearing aid wearers have it all with the greener AgZn battery option, including improved shelf life, the flexibility to use either conventional or rechargeable batteries, and increased energy in a smaller casing.

ReferencesEllison, J.C. (2011). Inductive recharge field trial. Starkey Hearing Technologies, Technical Paper.

ICOM (2008). The greenest generation: ICOM survey reveals older demographics as biggest users of green products. The Free Library. Retrieved from http://www.thefreelibrary.com/The Greenest Generation: ICOM Survey Reveals Older Demographics as...-a0184380767.

Kochkin, S. (2002). MarkeTrak VI: Consumers rate improvements sought in hearing instruments. Hearing Review, 9(11), 18–22.

Kochkin, S. (2012). MarkeTrak VIII: The key influencing factors in hearing aid purchase intent. Hearing Review, 19(3), 12–25.

Figure 2: Starkey Hearing Technologies’ new spare cell charger. The charger can be powered via a standard wall outlet or USB computer connection. LEDs notify the user of the charge state.

Table 2: Starkey devices that support silver-zinc rechargeable batteries.

Exclusions: X Series Power Plus BTE 13, 3 Series Power Plus BTE 13, Xino RIC 10, Xino Tinnitus and Xino Classic

© 2014 Starkey Hearing Technologies. All Rights Reserved. 4/14 WTPR2620-00-EE-SG

StarkeyPro.com

Global Headquarters6700 Washington Ave S Eden Prairie, MN 55344

Product Family and Device Style (non-wireless ONLY)

3 Series and Tour RIC 312 (non-wireless)

3 Series and Tour BTE 312 (non-wireless)

3 Series ITE, ITC, Half Shell and CIC 312 only (non-wireless)

X Series and Ignite BTE 312, BTE 13

X Series and Ignite RIC 312, RIC 13

X Series and Ignite ITE, ITC, Half Shell and CIC 312 only (non-wireless)

S Series iQ BTE 312, BTE 13

S Series iQ RIC 312

S Series iQ ITE, ITC, Half Shell and CIC 312 only (non-wireless)

S Series BTE 312, BTE 13

S Series RIC 312

S Series ITE, ITC, Half Shell and CIC 312 only (non-wireless)