#24 VOLT ALTERNATOR VOLTAGE FULL#

Make sure no electrical equipment is “on.” Connect a VOM to the bus and run the engine.

#24 VOLT ALTERNATOR VOLTAGE FULL#

This will provide full bus voltage directly to the field. With the alternator field isolated from the regulator, connect a jumper from the B+ alternator output to the field terminal. Perform a test called “full fielding” the alternator.If the resistance is “0”: the field circuit is shorted, which makes the rotor suspect. If the resistance is high, not steady or infinite (using an analog VOM), you may have bad brushes, slip ring contamination or an open rotor. If it’s not, remove the belt or alternator, if gear-driven, and slowly rotate the output shaft by hand. With the F1 and F2 (if provided) field terminals isolated, measure for a resistance of approximately four- to eight-ohms depending on whether it’s a 12- or 24-volt system (respectively). If not, check the regulator and associated connections, conductors, breakers and switches. Verify field (F1) input voltage, which should be the approximate bus voltage.Failure of either of these tests would be cause to remove the alternator.īut, if there is no tug, or if it is very weak: If that does check out okay, switch the VOM to AC volts and verify a maximum of one (1) volt AC into the bus. For 12v or 24v systems, if this is less than 13.5 or 25.5 volts respectively, when above 1,500 RPM, the alternator output is low. Connect a VOM to the B+ terminal and measure the voltage with respect to the ground. To do this, run the engine with the typical load. If there is a tug when the alternator rotates electrical output has to occur.Įven if there is a tug you still need to verify that the aircraft’s alternator can carry a load. Truth is an experienced mechanic can perform 95% of the steps to troubleshoot your aircraft’s alternator using a hacksaw blade and a Volt/Ohm Meter (VOM) – often referred to as a Digital Volt Meter or Multimeter.Įnergizing the aircraft’s alternator circuit while the unit is NOT running creates an electromagnet, so when you hold the hacksaw blade against the housing you will get a magnetic “tug” which indicates the alternator is creating a field. So if there’s a charging system issue, complete the following basic troubleshooting steps before removing the aircraft’s alternator. Unfortunately, any of these issues will often lead to a “failure” indication. There are a number of things which may look like alternator problems that aren’t. The real issue could well be something else under the cowling.

Keep in mind that just because the alternator went off line, it doesn’t mean the aircraft’s alternator itself has failed. The problem is simply that not enough troubleshooting was done before pulling the alternator off the airplane. Unfortunately for the aircraft’s owner, all too often when we test these “failed” alternators we find that they’re actually working fine. As the Director of Product Support for Hartzell Engine Technologies LLC (HET), I’ve had the opportunity evaluate aircraft alternators that arrive here for warranty consideration.

24 volt alternator voltage