Charging Systems

Mechanical Difficulty:

The Basics:

The battery stores power chemically, the alternator converts the engine's rotating motion into electrical energy, the Voltage Regulator (also known as the "Alternator Control Unit", or ACU) controls the alternator's output to keep the battery charged, but not over charged (which results in boiling out its acid).

The Usual Scenario

Your battery started discharging during your last flight. You shed loads by turning off unneeded equipment until you arrived at the airport and landed normally. Congrats on handling the inflight portion properly. Now how do you get it repaired?

You need to find out exactly which part failed. The usual FBO response is to replace the alternator AND the voltage regulator. They don't have to do much troubleshooting and they sell lots of expensive parts. A Field Rep for Kelly Aerospace, one of the largest OH shops for alternators, came to an FAA Safety meeting and told the attendees that 8 out of 10 alternators returned to them as cores for OH worked when tested before disassembly. He stated that A