Y'all are doin' it wrong. You need a spare battery on the charger at all times, and the batteries don't last if you leave 'em in the tool to set in between uses; when you do use them, take them from the charger (plug in the spare) and make sure to drain them. Believe it or not, batteries must be "trained".
Laptop batteries are similar; every three months or so, they need to be run right out of power, then plugged in for recharging.
I don't make the rules, I just report.