Originally Posted by Camel
I didn't/don't carry wall chargers/converters. I submit that doing so is the the most cost effective & convenient option (in most parts of the world).
Except maybe where the wall plug configuration is different in other countries (eg, Australia has three flat-pronged sockets at an angle compared to the North American set-up). Even so, the cost these days for a package of a charger and a set of, say, four AA 2500mA batteries is pretty darned good.
I tour and ride randonnees with equipment (rear blinkie lights, mini-radio, MP3 player, head-torch) that require AAA batteries. The AAs are reserved for my camera (2), PocketMail (2) and back-up LED front light (2). So there is some interchangeability there, and the Energiser charger I have acquired while in North America can recharge both sizes (a pair of each size at once). The recharger, when folded down is no bigger than an ordinary wallet (albeit fat with cash!).
I am somewhat dumbfounded that people persist in buying alkaline or even lithium one-use batteries for their energy uses on bicycles. They might be OK in emergencies, but the initial cost of nickel metahydride batteries (and for that matter Ni-Cads) is far outweighed by the number of recharges, let alone the fact reduced amounts of toxic metals are going to landfill. Perhaps it's the idea that rechargeables are rated at 0.25V less than disposables and people fear their equipment won't operate at full strength <shrugs shoulders>. I've not had any problems in that regard.
A recent high-profile long-distance randonnee event very strongly suggested using disposable batteries instead of rechargeables for lighting. I found that very odd -- theoretically, with around 140 riders using, say, 8 batteries each on the ride, that's over 1,000 batteries going into the garbage... I didn't dispose of any thanks to the SON dynohub up front, and the rechargeables out back on the blinkies.