APM 2.5 Power Module, get one... scratch one more item from the list - http://diydrones.com/forum/topics/kevin-finisterre-diydronesafety-a...

The APM 2.5 Power Module is a simple way of providing your APM 2.5 with clean power from a LiPo battery as well as current consumption and battery voltage measurements, all through a 6-pos cable. The on-board switching regulator outputs 5.3V and a maximum of 2.25A from up to a 4S LiPo battery. The Power Module comes completely assembled with your choice of Deans orXT-60 connectors, and wrapped in shrink tubing for protection.

Specifications:

- Max input voltage: 18V
- Max current sensing: 90A
- Voltage and current measurement configured for 5V ADC
- Switching regulator outputs 5.3V and 2.25A max
- 6-pos DF13 cable plugs directly to APM 2.5's 'PM' connector

http://store.diydrones.com/APM_Power_Module_Dean_Connectors_p/br-ap...

http://store.diydrones.com/APM_Power_Module_p/br-apmpwr.htm

http://code.google.com/p/ardupilot-mega/wiki/Voltage