With the bone, I charge for 4 hours the day before a tourney and it lasts all day with no problems.
According to the paperwork that comes with it, it reckons that you can use a fully charged one for about 12-15 cases of paint (think thats what it said). As i only play once a month, it will still work for the next tourney but I just charge it again anyway. Half the team bought these and none of us have problems during the day, its only the numptys that told us they were a waste of money.
You can get them from fish on here there his company exl paintball. We did buy ours direct from dueydogg in america but this was over a year ago,