Overview

Many devices on-board the rocket require electrical power. Providing this power is made more difficult by the environment of a rocket launch.

Best Practices

It is strongly advised that any device which has the capability to initiate energetic systems have a switch directly on the power line of the device. This mechanical switch should inhibit any energetic system from being discharged until power is applied. It is also strongly advised that switches are unable to actuate under flight conditions. Switch terminals should be solder or crimp type with heat shrink covering the terminal. ESRA strongly recommends crimped connectors covered in transparent heat shrink. All power connections in the vehicle should be fully strain relieved and either soldered, crimped, or locked in a screw terminal. All power connections should pass a "pull test." The first time energetic systems are powered on there should be no energetic materials present and inert indicators (Christmas tree lights, multi-meter) should be used to verify that no spurious were commanded.

Power Sources

A variety of batteries can be used to power systems during integration and flight.

9v Battery

Many commercial altimeters will run well on a standard 9v battery. These batteries should NOT be "Energizer" brand batteries due to the press fit manufacturing process which is prone to fail during flight loads. A commercial 9v battery should be tested to at least 9.0 v prior to flight.The battery should be fully constrained in all axis. The battery clip should be mechanically connected to the battery and strain relieved. Be careful leaving the terminals exposed. The close proximity of the terminals on 9v batteries makes them prone to shorting if a bolt or stripped wire is dropped into the avionics bay.

Lithium Polymer Batteries

Lithium Polymer batteries offer excellent power to mass ratios, deliver very good current discharge, and are easily available. These batteries make for an excellent source of power. They do incur some risk however. If these batteries are overheated, punctured, overcharged, over-discharged, or the max current rating is exceeded they can explode, deflagerate, or cease to function. These batteries should only be handled by someone familiar with the risks and caution should be exercised when working with these batteries.