I frequent a couple of different cycling forums. I read and participate at Bikeforums.net (as acidinmylegs) and on Roadbikereview.com and MTBR.com (as James@GearReview). I which subforums I read really depend on what I am doing at the time. If forks are my current interest, I'll be on MTBR's Shocks forum. Lately, though, commuting and touring have caught my attention -- I do a lot of the former and, some day, would like to try the latter -- and both Roadbikereview and Bikeforums have active commuting and touring sections. This time of year, though, everywhere people are turning their attention to lights. I do the same, it's hard not to as you look out the window and see less and less daylight. Currently, here at roughly 45 degrees lattitude, we're losing about 4 minutes a day. 2 in the morning and 2 in the evening. Not good. LEDs keep coming up in these discussions and with good reason. I am solely using LEDs as my lighting these days because I like the whiter light, the smaller sizes and lower weight. I really like the fact that the LEDs themselves are practically indistructable. My favorites so far are DiNotte's lights -- they are the smallest. CatEye's are brighter, but larger. I like small.
One thing that is always mentioned, though, in regards to DiNotte's lights are the batteries. You see, they make two versions of most of their lights, the less expensive Pro series, that uses standard AA batteries, and the Endurance series, which use more expensive, longer lasting Li-Ion batteries. With NiteRiders new MiNewt out, I have seen many... well, not complaints, but concerns about DiNotte's use of AA batteries for the Pro series lights. Having used both, let me see if I can clear some things up, and explain why, in my mind, AA batteries represent a strength, not a weakness.
As I mentioned above, LED last almost forever -- 50,000 hours or so, anyway. Batteries do not. Li-Ion and NiMH batteries are good for about 500 charge cycles. Older NiCad batteries are good for about 1000 charge cycles. This usually means that you'll need new batteries every 2-3 years for an NiMH or Li-Ion system. Think about that. This is a recurring cost. Proprietary batteries can run anywhere from $50 to $200 depending on brand and type. AA's are about $10 for a four-pack of higher capacity batteries.
As time marches on, battery capacities continue to rise. Right now I am running 2400mAh AA's in my DiNotte systems. Two years ago, I thought 1900 mAh batteries were incredible. My point? As battery technology improves, rest asured that it will be available in the AA standard size, too many devices use that size to ignore it. Which brings me to my next point.
AA is a standard across a wide range of devices... everything from laser pointers to clocks use it so the development costs and production costs are defrayed by a larger customer base. This keeps the incentive for innovation high and the incremental costs -- costs per user -- very low. This is part of the reason for the cost difference between proprietary batteries and standard off the shelf sizes.
Not only are the batteries themselves easily replaced, but the other componets are, too. The charger that DiNotte uses is a standard rapid charger. Need to charge from your car for that 24 hour race? Car chargers for AA batteries are cheap and redily available at Radio Shack. The connectors are available at Radio Shack and the battery holders are available at Radio Shack. This makes making and having spare batteries dirt cheap and making and extension wire -- you know, in case you want to run that bar light on your helmet -- a question of 5 minutes with a solder iron and $1 worth of parts.
With all of the available parts, there is no reason to limit yourself to AA batteries, need more run time? Don't mind a little extra weight? Run C cells. Four C batteries have the same voltage, but over twice the capacity making them a great idea for longer forays into the woods.
Now, those are the benefits -- namely, interoperability, low cost, ease of replacement and ease of expansion. There are a couple of drawbacks. First, ease of use. It is much easier to just plug in the correct power supply into the correct hole and have the battery charge. Much faster than taking out each battery. Second, run time. Proprietary batteries generally have a longer run time (than the AA batteries, not the C batteries) because they aren't locked into one shape, i.e. a small cylinder. But that's it. For long term reliability, my money is on AA batteries. In fact, if I were to buy a light system today, I'd be taking a long hard look at DiNotte's Pro series because as I see it, running off the shelf batteries is a benefit, not a detriment.