Your batteries run out at:
- A convenient time
- An inconvenient time?
Of course, by definition ist is 2. So here’s three tips.
Camera batteries: always charge. Daily. Never leave home without fully charged batteries (main, and a backup). For your Litium Ion (LiIon) batteries, do not worry about discharging (though if you wish, you can fully discharge and recharge a few times a year).
Flash batteries: use rechargeable NiMH AA batteries. They refresh the flash more quickly between shots, and they are reusable. But they will lose charge, and occasionally need resetting. So: get a conditioning charger (Maha or Lacrosse – Google them). And they will run down by themselves, so before a shoot, top them up. Also – change batteries for every segment you shoot.
General: use equipment that has AA batteries (e.g. traditional pocketwizards) rather than funny (hard to find, expensive, small capacity) batteries. If funny batteries are inevitable, like in your light meter, then always carry a spare.