Better portable speakers usually mean harsher power consumption, which makes it problematic for extended playback during outings and other outdoor activities. While it won't exactly solve the dilemma permanently, Devotec's Solar Sound Bluetooth Speakers should help you squeeze a little more juice out of the battery.
The wireless speakers can take tunes from any Bluetooth-enabled device, including phones, iPods and computers. Alternatively, you can plug the music source in via a 3.5mm jack, if you'd like to cut down the power consumption even further.
Main features of the speaker unit include dual 2-watt drivers, support for Bluetooth A2DP and AVRCP profiles, top-mounted solar panels and a 1500 mAh rechargeable battery unit (which is the same battery panel used by most smartphones). It can draw a full charge via USB (four hours) or directly from the sun (between 12 to 24 hours, a pretty acceptable number). The battery can last for 8 hours of use at medium volume, even longer if you leave it out in the sun while playing, making it ideal for outdoor activities.
Apart from it, the Solar Sound also comes with attractive touch-sensitive button controls and a built-in mic, so you can use it as an amplified speakerphone when connected to your handset. It weighs a light 260 grams and measures 16.5 x 5.5 x 5.5cm.
The Devotec Solar Sound Bluetooth Speakers are available now for a pretty steep asking price of $96. Considering how long it can last you on the road, though (8 hours, plus, possibly, an hour or two when used under sunlight), the cost sounds worth it.