I've read some things about these new Sanyo batteries and how they are an improvement over normal NiMH batteries in that they come ready charged and they discharge very slowly. Everything is at a price of course, and these retail at £10 ($20) for 4. Given that an F5 would take 8 and you might want a spare set, things could start to get expensive and I'd appreciate any views from anyone who has tried them. Thanks, Peter