Charging Issues

[Flynnupe94]

Hello my fellow Mooney Pilots, While out flying yesterday the  Voltage light came on and my JPI showed that the Battery was being discharged. Im not sure if this is an alternator issue or something else. I know its not a battery issue since I recently installed two new Concorde batteries about a week ago. This is the first time that the voltage light has come on. I was up flying on Fri with no prroblems. Any ideas?

[N201MKTurbo]

It could be many things. The first place I would look would be a visual inspection of the alternator wiring to see if any wires broke.

[Flynnupe94]

N201MKturbo I ran accross your reply to another pilot on Dec23. You asked him if there was any whining in the audio. Thats one thing that I did notice about my problem yesterday. There was a whining sound on the audio that wasnt there on my previous flight on last fri. What does the whining mean?

[Nathan Peterson]

Possibly one of your diodes is inop. on your DC alternator can cause whining noise.... check your wiring for a broken wire near your ALT.  as MKturbo said... check to see if your getting battery power at field post on your alt.  then we go from there.

 

Nate

[N201MKTurbo]

Whining is indicative of a lost phase in the alternator.

 

Normally the alternator makes three phases spaced 120 degrees apart. The positive and negative halves of each cycle are rectified with six diodes in a three phase full bridge arrangement.

 

If you lose any part of that it will increase the ripple current and you will hear it as a whine in your audio.

 

If you lose one diode you will lose one of the six half phases. If a field wire comes loose you will lose four of the six half phases.

 

One diode coming loose will generally not affect the performance much, losing a phase wire will reduce the output significantly and cause a loud whine.

 

These faults are almost always caused by fractured solder joints in the alternator and can easily be repaired by an alternator shop.

[ArtVandelay]

Try resetting the alt field CB

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[Tommy]

I had the pleasure of trouble shooting the eletrical system lately. It couldn've been much worse. The best info online - in an easily digestible format - is Mike Busch's EAA webinar on "troublshooting electrical system" It also covers the "whine." The most important things are

 

1) diagnose the problem methodically - don't ever let your A&P talked you into "ah, I suspect it's the ___________ (insert the most expensive component here). Let's get a new one".

2) you will walk away knowing your eletrical system so much better and it's no longer scary!

 

Good luck!

[Flynnupe94]

Thanks guys for all of the info, you guys are awesome....Keith

[laytonl]

Does the radio noise vary with RPM?  If so, I suspect it's a bad diode.  If it varies with load it is likely the regulator.  Lee

[Flynnupe94]

Hello guys this problem seemingly has no ending. After checking the wiring and hooking up a voltmeter, my alternator was determined to be bad. I picked up a brand new alternator and my mechanic installed it, problem fixed right? no. My mechanic said that after turning on the master and starting the engine the ALT out CB is popping. The ALT is producing 28V however there still is an issue going on. I never had any problems with any CBs popping or any other issues with the charging system  until I put in this new alternator. Anyone have any ideas?

[Yetti]

Voltage regulator failed and took out the alternator or wire broke and took out the alternator. Start at the battery.   All terminals need to be shiny bright clean.  Could be as easy as one of the battery connections is loose.   Check the master solenoid connections.  Emery cloth and wire brushes are your friend here.

[N601RX]

Are both your batteries deeply discharged?  Try topping them off with a electrical charger 1st.  It may be possible under a discharge condition they draw more charging current than the breaker can handle.  If the breaker is weak this may be exaggerated.

[Flynnupe94]

The Batteries are brand new. Ill recheck the connections when I go to my hanger..Thanks