Bag that you can use USB devices with the power of the sun
If you have this, you can keep listening to the iPod endlessly, it's limited in fine weather.
Details are as below.P.o.e. - family - group - e - anchorageproduct
The bag has a 12V cigarette lighter socket and a USB connector, and it seems that you can charge using two large solar battery panels. It is waterproof so it will be safe even in rainy weather. It seems to be selling for $ 255 (about 30,000 yen).