This is a very compact unit and great for occasional use. The idea of carrying a battery as a backup for a battery powered device never really seemed worth it to me. I mean, if my iPod ran out of juice, then so be it, I would wait to listen to my tunes until I get home. This all changed when I got an iPhone.

With the iPhone I replaced my iPod classic and mobile phone with one device. So now I was listening to tunes, watching videos etc and then I found I had no battery left to make or receive phone calls. This is where the TuneJuice 2 really really helps. I leave mine loaded with 4 alkaline AAA batteries and then just throw it in my cars glove box. On the times it has helped me, it gave my iPhone a quick ten minute charge to make an important call. The second time I left it charging for about three minutes and again it enabled me to finish the call I was on. The AAA's were still good.

So this could well be a very useful device, to ensure you don't get caught with no juice to call home.