> Also, people seem to have no problem doing exactly this with propane tanks (in the USA) for their BBQ grills. The tanks you exchange are definitely not as nic

> Also, people seem to have no problem doing exactly this with propane tanks (in the USA) for their BBQ grills. The tanks you exchange are definitely not as nice as the ones you can buy new and get filled but the convenience of being able to exchange a tank outweighs a lot of people's desire to get their tank refilled. Except that no one cares what their tank looks like - they only care about how much it holds, or rather, how much gas they're going to get out of it, and whether it leaks. The same is true of batteries, and that's the problem if batteries degrade with usage, heat, deep discharge, and so on. Oh, and I do try to get the nicest propane tank when I exchange. I'm not the only one.