Opinion Article on Disposable vs. Rechargeable Batteries

This article is copied from an email I wrote recently in response to someone inquiring about my personal experience with the CII BTE and the relative advantages of disposable vs. rechargeable batteries.  It is intended as an opinion article and not a statement of facts. Please note that I am only speaking about the CII BTE below. There is now a new BTE for the Clarion called the Auria, which I have not had a chance to try yet. The Auria is supposed to get up to 9 hours between recharges with its rechargeable batteries--or you can use a separate little battery pack that holds a "AA" battery (disposable or rechargeable), each of which is supposed to last a whole day.

If performance is the Clarion's advantage, battery life is its disadvantage. No doubt.  However, it is not as bad as some people make it out to be, so I'll try to clarify a few details and share my personal experience with the CII BTE so that you can make up your own mind.

When I first started using my CII BTE, I got about 6 hours with my CII BTE, using the standard battery. When I wake up, I reach for my BTE and I throw a fresh battery on it. I have two more batteries that I carry with me on a small keychain battery holder that comes with the implant, and change the battery twice during the remainder of the day day.  It only takes a quick 10 seconds to do it--honestly not a big deal at all.  Then, when I go to bed, I put the batteries back on the recharger so that they're fresh for the next day. It's really as simple as remembering to take a vitamin with breakfast in the morning.  For me, personally, it has been an easy and smooth process that isn't very inconvenient, although longer battery life would certainly be welcome.  Although I have the option of purchasing extended-life batteries that would enable me to get approximately 10-12 hours per battery, I have not found felt it necessary to do so and am comfortable enough with batteries that last six hours in between recharges.  

The rechargeable batteries are designed to last up to a year, after which point they should be replaced since they do not last as long.   In my experience, battery life declined from about 6 hours apiece when they were new, to about 4.5 hours after a year of constant use (I have since replaced them for new batteries and am once again getting 6 hours).  Surprisingly, the difference between getting 6 hours and 4.5 hours per battery is rather significant, because 6 hours per battery meant that I would change them twice during the day at most.  At 4.5 hours, I sometimes had to change it more often than that, which begins to feel a little inconvenient, whereas six hours per battery honestly did not.

The Nucleus ESprit 3G BTE and Med-El's BTE both use 3 disposable hearing aid batteries. Battery life with the Nucleus ESPrit 3G said to be between 20-119 hours, which is significant, but it's important to be aware of what accounts for this range in battery life. The 20 hour figure is based on using a speech strategy called ACE, which is "preferred" by about 70% of Nucleus users. The 119 hour figure is using SPEAK, which is preferred by only about 20% of Nucleus users, so the average user is far more likely to experience something closer to 20 hours than to 135 hours--unless he were lucky enough to perform best with SPEAK or were willing to sacrifice sound quality of ACE for the longer battery life of SPEAK.  The weighted average expected battery life for Nucleus users is therefore 44 hours.  Also, it's also important to realize that of the reasons that the Nucleus and the Med-El's BTEs are able to get longer battery life than the Clarion's BTEs is because they are more limited, power-efficient versions of the body-worn processors, whereas the Clarion's BTEs are essentially fully functional miniatures of the body-worn (with higher power requirements). For instance, Med-El's BTE is incapable of running certain speech strategies which its body-worn processor could do (such as "n-of-m").  Similarly, the Nucleus ESPirt 3G appears to be incapable of incorporating ADRO, which is a new enhancement on the Nucleus that Cochlear claims may improve performance in certain situations.  Furthermore, the ESPrit 3G can only serve 20 of the implant's 22 available electrodes, unlike the body-worn which can use all 22.  In order to conserve energy, it effectively uses processing "shortcuts" in how it handles sound information which may result in greater differences in sound quality.  In contrast, the Clarion's BTEs are capable of just about everything that its body-worn processors can do, so no such limitations (present or future) are evident.  However, most Nucleus and Med-El users are quite happy with their BTEs and do not report frustrations with any possible limitations of this sort.

The key point here is that there are advantages and disadvantages to each approach.  Personally, I am quite happy to have the added functionality, performance, and power of the CII implant, even if its diminished battery capacity requires changing the battery a couple of times a day.  This is a decision that each person has to make up on his own, as he weighs what he feels is the ideal balance between battery life and the rest of the features and performance that each implant system has to offer.