Nowadays battery powered lighting technology is becoming more and more popular. They can be placed anywhere you desire, for you won't have to use additional cables. Lots of these devices have up to 18 hours of battery life on one single charge and can therefore run during the whole of your event. So called battery cases are available to recharge them. You simply have to place the spots into the case and connect it to the power supply system. Charging times may vary strongly between devices. They can be controlled via a wireless DMX connection, the stand-alone mode or master/slave function.
Using batteries has no negative effect on the intensity or clarity of the light. They are also on par with traditional spotlights when it comes to effects or their colour range.