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Monday, August 20, 2018

Doug's Domain

Doug Vetter, ATP/CFI

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Doug's 2003 Bose X
Active Noise Reduction Headset
Review

(Image: Closeup of revised Bose X)
An analysis of the 2003 Bose X redesign
from the perspective of a long time Bose owner.

What's New?

In mid-summer 2003, Bose splashed a full page ad in all the traditional aviation publications touting the "new and improved" Bose X. I had no immediate plans to buy a new Bose X, but I was very interested to see if Bose implemented the many recommendations I made in my last review, so I gave Bose a call to inquire about the upgrade path.

A brief conversation with a Bose sales rep revealed their plans. They would offer new headsets for sale in the next few weeks, but the retrofit battery box kits would not be ready until September. Although the sales rep pointed out that their policy is not to charge a credit card until the box shipped, I've never been comfortable having purchases "on the hook" for more than a few weeks, so I declined to purchase the retrofit kit at that time. The sales rep reminded me that they already had the kits on backorder, and if I wanted to get it as quickly as possible, I "should get in line as soon as possible". I thanked the rep for the tip, but still declined to buy it at that time.

Fast Forward

Fast forward to Mid September. I called Bose again to check on the status of the kits. The sales rep told me that they had slipped slightly due to manufacturing difficulties, but that the new ship date was about three weeks away. I finally relented and placed an order, primarily because Bose had not been known for missing deadlines and I figured they'd missed one deadline and that would be it.

Fast forward again...this time to early November. I had not received my kit yet, so I called Bose again. The sales rep apologized profusely and asked for continued patience, as they were continuing to have problems with vendors supplying the kits in quantity. At that point I'd considered cancelling the order, but since it wasn't costing me anything, I kept my delivery slot.

From the Horse's Mouth

Around that time, I got an email from the Bose Aviation ANR headset product manager. It seems as though he'd been surfing the rec.aviation groups and had noted my strong support (as well as occasional criticism) of the products.

When I contacted him and inquired as to the current status of the kits, he told me that they were having problems integrating the electronics of the retrofit kits with the existing headset electronics. And that's when I learned that the "New Bose X" (what I'll call the 2003 Bose X from this point on) upgrade was more than just a battery box assembly fix -- the electronics in the headset were upgraded as well.

I also learned that while customers of the new 2003 Bose X would likely get up to 40 hours of battery life (about 3-4 times as much as the original 9V based Bose X), retrofit customers would get only about half that, or about 20 hours.

The product manager offered to send me an entire headset when one became available. I told him there was no rush, because at that time the airplane I fly was in for a rather lengthy annual inspection and I wouldn't be able to do any serious evaluation of it anyway. Around Thanksgiving, the product manager contacted me again and said a demo headset had become available and offered to ship it to me as long as I'd be willing to secure it with a credit card. No problem.

Cut to the Chase

I had planned to keep the headset for a couple months and thoroughly test what I considered to be the chief selling point of the new design -- the 40 hour battery life. However, because I had the headset for a limited time and various factors conspired against me I managed to log only about five hours of flying with the new design before I started work on this article.

Normally, I wouldn't consider five hours sufficient time to evaluate all of the subtleties of any product like this, but given my long history with the Bose ANR product line and two years / 300 hours of experience with the Bose X, I didn't find it much of a surprise that I quickly developed strong opinions on the new design.

In the interest of getting unbiased feedback about the headset, I allowed a friend who still uses passive headsets (in other words, a possible ANR convert) experience the new design first hand. His comments are integrated with the following assessment of the 2003 Bose X.

Advantages:

Battery Box Smaller, Select Ergonomic Improvements

I like the long, thin form factor of the battery box. When I fly with my existing headset, I have a hard time trying to cram the large (deep) battery box into the side pocket. This new battery box is physically much smaller and fits nicely into the side pocket. The new box fits comfortably in the hand, and all controls are within reach of one's thumb. In other words, someone thought about the ergnomics during the design of the box, and that's a good thing.

Another plus is the fact that the power switch and power monitor LED are on the same face of the box. This makes it easier to see the effects of a change in power state.

The momentary switch used to turn the ANR power on and off works acceptably well. From an engineering perspective it's not as elegantly simple as a single-pole switch, but it gets the job done. To turn the power on, you just tap it. To turn power off, you hold it down for about one second.

Increased Battery Life (I hope)

Fortunately, the active noise reduction performance and sound qualities appear to be the same as the original Bose X, which is to say "outstanding".

This says a lot about the improvement in the design of the electronics. Although I haven't been able to personally verify the claim of 40 hours of battery life, if Bose has indeed managed to produce that kind of battery life and maintain the same ANR performance provided by the current 9V power source, I will be impressed.

Automatic Power Off (APO) Support

Thankfully, Bose has FINALLY integrated Automatic Power-Off (APO) as I suggested two years ago. Increased battery life means NOTHING if you forget to turn the headset off before you pack it in your flight bag only to pull it out a day or so later to find dead batteries.

Some simple testing revealed that APO appears to work well, and will turn off ANR power in about one minute if the environment is sufficiently quiet. When I tried to carry on a conversation in the vicinity of the headset (or more to the point, the microphone), it would take somewhat longer to shut off.

This would seem to indicate that the APO technology is integrated with the battery box (as it should be, since APO has little to do with panel-mounted units, so putting it in the headset would make little sense), so retrofit customers should benefit from this feature.

Post Sale Support

I must make special recognition of Bose's continued committment to post sale support. And, I'm not talking about the kind of support people encounter when they realize that their headset has lots of parts that break all the time *cough* Lightspeed *cough*, but rather what they do when they recognize they have not lived up to customer expectations.

Case in point: In mid-December, shortly before writing the first draft of this review, I received a package containing a letter that apologized for the continued delay in shipment of the retrofit battery box assemblies AND a new pair of Bose Quiet Comfort noise cancelling headsets (a $200 value).

Now, I'll grant that this was largely a slick way to clear out inventory to make way for the Quiet Comfort II product as well as grab a few more write offs in prep for tax time, and it certainly did nothing to accelerate delivery of the upgrade, but it was a nice way to say "we apologize and appreciate your patience".

Disadvantages:

Unfortunately, the headset has several design flaws, and sadly, some of the flaws are repeat offenders. Read my last review for more information.

Power Monitor LED washes out in direct sunlight

Bose chose to install the power monitor LED below the surface of the case and use a white translucent filter to make it appear larger when it illuminates. They also apparently changed the LED flash rise time such that the LED "rises and falls" more slowly. The effect is kind of neat.

The problem is that direct sunlight it hits the filter and completely washes out the LED, which makes it very difficult to determine the power state at a glance. The fact that the LED behaves less like a "strobe" makes it even more difficult to discern the change in state. To their credit, however, they did think about night operation. Tapping the on/off button twice in quick succession after the power is turned on dims the LED for night operation.

In contrast, the existing (9 Volt) battery box extends a commonly-available LED a bit above the surface of the case. It flashes once a second...which isn't fast enough in my opinion, but I can make up for that by looking directly at the illuminated diode junction. Not possible on the new box -- the filter intentionally obscures the junction.

(Image: Volume control closeup) Poor Design of Volume Controls

One of the biggest problems I had with the existing battery box was the awkward concentric volume control. When I first saw the new battery box in the ads, it appeared that the volume controls were exposed only on their knurled edge. Clearly, as the photo shows, that is not the case.

Not only is the entire face of each knob exposed, the knobs require virtually no force to turn, which means they change position all too easily if the box brushes up against anything or (in my case) is wedged into a storage pocket.

To make matters worse, there are no detents to provide any additional resistance OR any kind of visual or tactile feedback to communicate changes in volume level or an indication of the current volume setting. Once again, I am forced to go through the laborious process of fixing volume in one ear, and then adjusting volume in the other ear until it matches. Sure would be nice to be able to flip both knobs "three clicks down" to achieve the desired volume, without having to do the "balance dance".

Frankly, I've never understood why Bose integrated individual volume controls into an aviation headset. I have never needed to reduce or turn off the volume in one ear in 15 years of flying (and 1 year of flying with a stereo intercom), and I can't envision a situation that would require this feature. If I had to make a single recommendation, it would be to dump the individual controls in favor of a single control.

If two controls were deemed mandatory, they should be constructed to move as a single unit, so quick volume tweaks don't affect the balance. The controls should also be silkscreened with a color gradient (say green to yellow to orange) and numbers to provide a simple indication of the current volume level, as well as the difference in level between the two controls.

The bottom line is the new volume controls are WORSE than the original. I will likely have to set them and then use some tape to fix their position...which sort of defeats the purpose of having volume controls in the first place!

(Image: Battery door hinge detail)Flimsy Battery Door

Hmmm...Deja Vu. The battery door, like the remainder of the battery box, is made of injection moulded plastic. If I were building this I would have manufacturered it out of aluminum: die cast, milled, or simple square stock...take your pick. Bose, of course, decided to go cheap again.

This time, the effects of the marketroids and bean counters are more severe. While Bose apparently took the hint that the battery box lid should be attached to the box so it isn't easily lost (indeed, a plus), the rounded design of the case necessitated a very small hinge...which probably wouldn't have been such a big deal if it was made of a material with sufficient strength to withstand the forces of normal and accepted use.

The problem is the hinge is SO small and flimsy that every time I open it and it binds (another indication of poor design, incidentally) I think I'm going to snap the small plastic tips off of the hinge, breaking the cover. And when (not if) that happens, operation of the headset will be at risk because the batteries can pop out quite easily...unless, of course, I were to break out that roll of tape and fix the problem. I repeat: acceptable for a $20 toy, but shameful on a $1000 TSO'd headset.

(Image: Battery cover open)Again, I don't know what Bose's engineers were smoking when they designed this battery box, but this is a clear case where form has overruled function. Spare me the slick-willy marketing-driven case design and build the box out of simple square black anodized aluminum stock so it's possible to dedicate the space to a more substantial hinge and cover.

If Bose must build everything in plastic, I suggest they check out the Olympus C-2040Z digital camera for an example of how to build a proper battery compartment cover, hinge and locking mechanism. It's not that hard. A couple days (if that) with Pro/E and it's done. Really.

No Friction Adjustment on Microphone Boom Pivot

This design is also worse than the original. While I didn't like the existing pivot for various reasons, I learned to tolerate it, and it never let me down. Once I set the position of the boom, it stayed put. Not so with this new design.

The friction of the redesigned pivot is, in my opinion, far lower than it should be. The boom moves when I nod my head or during turbulence encounters. I cannot see any way to adjust the friction of the pivot, and as sure as I know the sun will rise in the morning I know the friction will further decrease over time due to simple wear and tear. Before long, I expect the boom to be sagging, and I wonder if Bose will offer to replace the entire assembly for free when the time comes...I doubt it.

(Image: Microphone boom swivel detail)Now, don't get me wrong...I like the physical design of the new boom. It's just that the swivel should have been designed with a means of adjusting the friction of the joint and perhaps some detents functionally equivalent to the existing Bose X boom to prevent sagging in the event the friction isn't set high enough.

No Rechargeable Battery Support

I am really becoming uncomfortable using alkaline batteries in any of my battery-powered devices. Batteries of all kinds are a horrible threat to the environment, and even if you have ready access to a proper disposal facility, the thought of using something disposable when something reuseable (ahem, RECHARGEABLE) exists, is just plain wrong.

I use 1800 MaH NiMH AA batteries in my digital camera. I bought a set of four three years ago for $15 along with a good charger for another $15, and have recharged them at least 50 times with no apparent drop in ampacity.

This not only makes good economic sense...it makes good environmental sense, as I've avoided throwing 200+ batteries into the local landfill...which brings me to my point: I should have the option of using high-capacity, commonly-available rechargeable NiMH batteries in this headset, but Bose's engineers failed to provide even a hardware-selectable option to support the voltage profile of a rechargeable battery.

Bose support personnel have confirmed that while I could use the rechargeables in the headset, battery life would be much shorter due to the lower voltage of the rechargable combined with the higher operating voltage necessary for proper functioning of the ANR electronics. They have also stated that use of rechargeable batteries will prevent proper functioning of the power monitor LED. While they didn't indicate how the LED will malfunction, given prior experience, I imagine it will show "battery low" far earlier than necessary, which will undoubtedly lead to complacency regarding replacement of the batteries...until the headset suddenly powers down on an approach into low IFR. Not fun.

If voltage requirements could not be met by the use of two rechargeable batteries, they should have used 4 AA or AAA cells and regulated the voltage down to that required. Had they used simple 1" square aluminum stock for the battery box case, four AAA's could have easily fit in the end of the box and a simple sliding cover used to retain them. This would have allowed the (safe) use of rechargeables and added the benefit of additional runtime provided by the additional cells. Seems pretty simple to me. Why didn't Bose do this?

Mono/Stereo Switch Access

Most people who buy the portable headset do so because they fly different aircraft regularly. It stands to reason, therefore, that anyone who might fly different aircraft would encounter both stereo and mono intercoms on a regular basis and need a convenient way to adapt the headset for use in each aircraft environment.

So, given the chance to build a new design from the ground up, what does Bose do? Relocate the stereo/mono switch from the exterior of the box to a recess in the battery compartment. Uh, right -- that makes PERFECT sense. In order to change this setting, you must open the (flimsy) battery door, pull out the first battery, and use a fine tipped pen or perhaps a sharp fingernail to move a subminiature DIP switch.

The final smack in the face? Assuming you're willing to jump through hoops and do this, DIP switches aren't rated for the number of cycles they'll likely receive in this mode, so premature failure of the switch is more than likely.

Overall Rating

3.0 out of 5 stars. For those keeping score, this is a full point LOWER than my original rating. I feel justified in lowering my rating for all the reasons mentioned above, but for one reason in particular: Bose had a chance to fix the obvious physical and electrical shortcomings of the Bose X Portable version yet managed to do more harm than good.

I believe the design flaws are the result of an outdated development model that fosters protection of so-called intellectual property and proprietary designs, and attempts to preserve unrealistic financials -- all at the expense of the customer. To their credit, these problems are not unique to Bose, but should serve as a warning sign to upper management that the lifeblood of their company is being drained by short-sighted thinking.

Bose management should encourage its engineers to get outside more often, talk to pilots, and review product designs with customers (under NDA if absolutely necessary) before they give the green light to production. Had Bose given me the opportunity to review this design before it left the drawing board, I'm confident that we'd have something that was functionally, ergonomically and cosmetically superior to what they released. It probably would have cost them a bit more to produce, but far less than the design shortcomings will cost them in lost sales and damage to their reputation.

I could almost excuse Bose for the blunders if the product competed on price, but this is marketed as a top-shelf headset that carries a $1000 price tag. For that money, I think it deserves more critical design analysis and better quality production techniques than it's received. Years ago, the headset was worth the premium. I'm not sure that's the case anymore...not only because the technology has become more commonplace, but because Bose continues to cheapen it in ways that lower the quality of the user experience.

I rely on Bose to provide the best ANR performance in the industry and they (fortunately) still do that. For that reason, I can still recommend the product. However, I can assure you that I plan to review competitors' products in the future to see if I can find a better balance between ANR performance, design quality, and price.


Update: 3/10/04 - Cable Assembly Arrives

I received the upgraded battery box / microphone assembly today. Bose apparently started shipping the new assemblies March 1st. This time their ship date was on target. The assembly I received is physically identical to the one provided by Bose for the review, and includes a new microphone/boom assembly.

Configuration via a DIP switch in the battery bay is required for headsets manufactured before June 16, 2003. The older, less efficient electronics in the "original Bose X" headsets will limit battery life somewhat relative to the widely published figure (40 hours), but I currently lack sufficient experience with the system to comment on battery life. I installed a set of fresh batteries with an expiration of March 2010, and will report my findings.

In reality, though, I don't really care about alkaline battery life, as long as it's as least as much as that provided by the 9 volt power source it has replaced. My second set of batteries will be 2100 MaH NiMH rechargables, and I can't wait to see how they perform in this application. I don't expect the battery indicator to work properly with rechargeables, but as long as the headset functions normally for 10 hours or so per charge, I'll be happy... because each charge will translate into one fewer set of batteries in the landfill (and more money in my pocket, for that matter).

Of course, the perk of rechargeables (particularly NiMH) is that with a proper charger / conditioner, it's possible to charge them from any point in their discharge cycle so battery life virtually becomes a non-issue.


Update: 5/22/04 - 50 Hour Flight Report

After several months and 50 hours of flying with the new Bose X portable battery box retrofit kit I figured I'd write an update to detail some of my impressions at this point.

First of all, as predicted, the volume controls have really been a pain in the ass. I really feel like giving the lead engineer at Bose a good thrashing for this blunder. The controls move unintentionally when I tuck the box into a side storage pocket or even when it merely brushes up against my leg (!), so I have to take extra care to use my index and middle fingers to hold the volume controls at maximum while I tuck the box into the storage pocket. Otherwise I go deaf in one ear (or partially in both). Am I nitpicking? Perhaps. But as I've said before, at $1000 a headset, I'm entitled.

On the upside, I'm very happy to report that the ANR performance has been great, and at times has seemed more effective than the previous design. I have no hard data, however. It may just be my imagination.

Battery life is also great. I got slightly over 25 hours on a fresh set of AA's before the power monitor LED started flashing yellow. At the time I noticed it, I had just departed Newport News, Virginia on my way down to Florida. As I was expecting to run into some weather later on, I decided to swap batteries in good VFR. I therefore have no data on the maximum possible run time, but I believe the test was a success nonetheless. The point of the power monitor LED is to warn of a low battery condition to prevent a sudden and unexpected loss of ANR, and it worked as advertised....with alkaline batteries, that is.

And speaking of alkalines, I know I said that my second set of batteries would be high capacity NiMH, but on that trip I needed predictable ANR behavior so I swapped in another set of alkalines. I'm hoping to make the next set NiMH.

Was the upgrade worth it? If it weren't for those $@#&! volume controls, I'd say "yes". If I had to do it over again, however, knowing what I know now, I would NOT have purchased the upgrade. Although the old box was nothing to write home about either, it didn't irritate me nearly as much. I miss it.


Update: 10/28/04 - Rechargeable Results

I finally installed a set of 2300 maH NiMH AA batteries and am happy to report that they were still going strong after about 20 hours of flight and eight weeks of self-discharge time. I pulled them out to charge at that time for unrelated reasons, but not before proving to myself that rechargeables are indeed a viable alternative power source for the Bose X.

It's pretty clear that one can fly a VERY long day on these batteries, charge them for a few hours overnight, get back the saddle first thing in the morning, and lather, rinse, repeat -- all the while saving the planet from yet another set of discharged alkalines.

As expected, the power status LED flashed yellow prematurely (after about 5 hours), but the headset continued to function normally, even in high noise conditions such as takeoff.

If you have a Bose X portable, I recommend you pick up a matching set of four of the highest-capacity NiMH rechargeables you can find, as well as a good charger. The extra set will allow you to make an inflight swap if necessary.


Update: 03/20/05 - Long Term Update

I've been flying with the "improved" (retrofitted) Bose X for over a year now so I figured I'd provide another update.

2500 mAH Power

First of all, high-capacity NiMH AA batteries are now available almost everywhere, given that Eveready has seen fit to market 2500 mAH varients in their Energizer brand. While my 2300 mAH "battery house" brand sets were adding up to 20+ hour runtimes, a friend gave me a gift of four of the 2500 mAH Energizers, so I started using them. In my experience, these batteries have more than enough capacity to drive the retrofitted (less power efficient) Bose X and last about 25 hours, or about 5 hours more than the 2300 mAH sets, on average. The revelation? No more AA alkalines for me.

Search ends where it began

For the last year, I've been looking for an inexpensive (yet high quality) noise cancelling headset to serve as a personal backup and co-pilot / passenger headset. The primary goal was ANR performance, followed closely by a reasonable price. I'm also not one to spend money on crap, either, so construction quality definitely factored into the equation.

If you've been reading my site or some of my posts in the rec.aviation newsgroups you probably know my feelings about the Lightspeed series of headsets, so I won't belabor that here. In spite of this, however, I decided to give them another look since they released their new flagship Thirty 3G set last year. I finally got around to taking one out of a display case at a local pilot shop and I was not impressed. The entire headset felt cheap. It was heavy. The plastic earpiece / headband interface felt like it would break if I breathed on it. Bose can't seem to make a decent battery box, but at least the thing feels solidly built -- in stark contrast to the cheesy Lightspeed control box. But, above all of those issues, what struck me most was the manner in which the earcups protruded far from my head in a manner I can only describe as strangely reminescent of Princess Lea. Hmmm, I thought...maybe the price is right. What's that? $560? I think not.

My attention then briefly turned to the FlightCom Denali, which at $520 was in my target price range, but appeared to have a cleaner, more professional look. I found them almost Peltor-like in that respect. However, in the end I was turned off by comments I read online like "I had a Denali for 3 days. That pretty much says it all". Most of the issues centered around performance of the ANR circuitry. A rumbling or howling noise seemed to be the biggest complaint. To their credit, this is the same problem that plagued many of the early Lightspeed sets. I'm not sure what causes it, but my guess is over-simplified circuitry and/or poor parts tolerances -- both indications of cost-cutting where it hurts. In any case, I had no plans to be FlightCom's guinea pig so I gave the Denali no further consideration.

Convinced that I wasn't going to find quality at the $500-600 price point, I also looked into the Telex Stratus 50D. The physical quality of the headset appeared to be better than the Denali, and many people reported performance of the DSP-based ANR to at least equal that of the Bose analog circuitry. Knowing the power of DSP-based audio solutions, I was particularly intrigued at the thought of demoing this unit. I contacted Telex with the promise of a thorough review if they'd send me one for evaluation, but Telex refused. They insisted I had to buy it. When I asked them if I could buy it direct with a 30 day money back guarantee, they said they didn't sell direct and I'd have to speak with one of their dealers. Unfortunately, the dealers I spoke to were not willing to do a 30 day trial under acceptable terms.

A few minutes after I got off the phone with the last uncooperative Telex dealer, I resolved that I'd just buy another Bose X and avoid the hassle and uncertainty of another brand. Now, I know what you're thinking. I have my gripes with the Bose X, but they are largely with the portable version and have little to do with the headset itself or its ANR circuitry. Yes, the battery box was designed by morons, but at least the headset is a light, attractive design, that works well. And then there is the phenomenal Bose post-sale support...an important factor in buying any modern electronics.

So, my search ended right where it started, with the Bose X, and I was out another $995, right? Not exactly. The happy ending to this story is that I found Tom at Avionics West selling new Bose X straight-cord units for $934 + shipping. While I'd normally be a little leery of going with the "low bidder", I'd known Tom online for some time and always enjoyed reading his experiences as an Avionics shop owner. He was far from a faceless discount house. After all, why go to Bose and pay list if they'd support me no matter where I bought it? Sold!

At this point, the only thing left to do in this review is to verify the longer battery life promised by the more efficient electronics, and I'll be sure to report my findings here when I have enough data.


Update: 03/22/06 -Battery Box Repair

The other day I was getting out of the airplane and failed to notice that the cord to my Bose X somehow managed to wrap itself around my angle. The result was predictable -- the headset and battery box came with me while the jacks stayed with the airplane. Crap!

Bose to the rescue. I called them the next day, admitted my blunder, and asked them what the cost would be to repair or replace the battery box / mic assembly. The friendly woman answered, "we'll do that as a courtesy repair, Mr. Vetter. No charge". Now *that* is customer service.

I used usps.gov to create a shipping label for $4.05 and sent the box out on a Thursday. The tracking information indicated that it arrived at Bose's repair facility in Framingham, MA that Saturday. Today, the following Wednesday, I received the repaired assembly.

I had accidentally forgotten to remove my Energizer 2500maH batteries, and Bose dutifully returned them along with a set of new AA alkalines. I popped the alkalines in to perform an acceptance test while my rechargeables made their way to the charger. All I can say is the unit works beautifully again and my little mistake only cost me $4.05. Thanks Bose!

2500maH Battery Review

The Energizer brand 2500maH batteries have been working very well in the Bose X and are able to supply the current necessary to drive the ANR circuitry under some pretty harsh conditions. The batteries are now sold in reasonably priced 8 packs, and I've bought a few of those to power everything I own that requires AA. The greater ampacity and maximum discharge current more than makes up for the lower operating voltage (in properly designed equipment, of course).

The only negative I've noticed is that their self-discharge rate is much higher than my previous-generation 2300maH units. I imagine this is caused by dialectric losses due to the high density of construction, but no matter, I can use the phenomenal LaCrosse charger (see below) to keep them charged and running at peak efficiency.

LcCrosse Charger

Batteries are only as good as the charger that maintains them, and in my case, the best equipment I've found for the job is the LaCrosse BC900. This thing is like four independent chargers in one. It can charge 1-4 AA or AAA batteries (you don't have to charge in pairs like most other chargers). It supports charge, discharge/recharge, and discharge/refresh modes and can run those modes individually on each battery. In other words, one battery can be in normal charge mode, while you can be refeshing another. Very neat. It also provides voltage as well as charging and discharging current information to show you the state of the battery at any point in the maintenance cycle. Well worth the coin, particularly if you depend on your batteries for critical service like I do.