On board battery status lights are great, but I like to interpret just what the lights are really telling me. The first time I take a so equipped plane out, I also test the receiver pack periodically with a voltage/load test meter and take note as the light changes. http://www.horizonhobby.com/products...ltmeter-HAN171

Every status light type I've used blinks for the briefest of time the red light if I quickly circulate both sticks at the same time. Digital servos are getting more common and more powerful. These servos really draw current and if your plane is loaded with these, you may need to rethink your battery. I's always a good idea to load test through the switch a least once to see if there a lot of loss in the switch, I've found a few obvious bad ones.

Besides chemistry type, there are three main things to know about your battery. Voltage, Capacity and discharge voltage @ load or what I like to call "current dump". For example: a NiMH AA battery typically has more capacity (more in the tank) than a NiMH 2/3 A, but the 2/3A battery has better dump (less voltage drop under the same load.)