I'll be taking my new E-PL5 on a two-week family trip overseas (UK). Instead of buying a UK battery charger, I'd prefer to just bring 3 or 4 pre-charged batteries. However, I'm not confident how long the things will hold a charge sitting wrapped up in the camera bag. I know that most NiMH batteries bleed charge pretty quickly, but I don't know much about these Lithium-Ion things. Will a fully-charged battery keep at least most of its charge for 9 or 10 days? Obviously if I got desperate I could probably find a charger in London somewhere, but I'd rather not have to semi-plan on that. This seems like a common question but some time searching hasn't found anything. Apologies if it's in an obvious FAQ I'm too blind to notice.