Alternator warning alarm coming on intermittently

[rbickford]

I apologize if this is an old topic. Could not find anything by searching. On a 2004 G1000 DA40, the alternator warning alarm comes 'for no reason''. This happens at least once an hour. Today in a bit of turbulence it was coming on way more often. Not sure if the turbulence is related. Just mentioning it. When it comes on you can see on the panel that the alternator is producing a charge, and that all is well.

Has anyone experienced this?

Thanks.

Bob

[Charles]

How many hours since the last alternator overhaul?

[Antoine]

Bob, it is advisable to replace the brushes of your alternator on a regular basis.
This is an inexpensive and very efficient way of avoiding AOG failures.
And since you have a G1000 which needs a lot of current, I recommend you consider the upgrade to a Plane Power alternator. These things will feed your G1000 and load your battery at idle, much unlike the regular alternator. Instead of depleting your battery during taxi, you will be charging it. No more alternator alerts at low rpm.

[rbickford]

Thank you for the responses. I just purchased the plane. New engine log in 04/12. No indication of any alternator work in the 1,000 since the engine swap. Makes sense that the brushes could be causing momentary loss of output. Speaking to someone who flew the plane about a year ago in a flight school setting, the alarm was going off then also, but less frequently. I will absolutely replace the brushes and make a note here about the fix here when it is done. Thank you for the Plane Power tip. A friend with a Cessna put one in eight years ago and no issues since. Prior to that was replacing the standard Cessna part on a regular basis.

Thank you

[Chromer]

Hi Bob,
There is a resister block that is attached to the alternator AUX terminal. If this resister block has a loose connection then you may get a intermittent alternator light. The service bulletin is MSB 40-058. After my alternator was rebuilt the block wasn't tied up properly and the connection came loose and the warning light came on. Just a thought.

[rbickford]

Hi Daryl. That is a good tip. Will get the service bulletin and look at the resister block. Appreciate the tip and the knowledge. Thank you.

[Fred]

Can you see the load on the battery when the alternator is showing failure?

I had the sensor that feeds the G1000 that is on a fragile piece of metal break. I had an "X"'ed out alternator and really nothing was wrong with it. Turned out to be the mounting bracket the sensor is held with. Never had to use the backup alternator since the load even with pitot heat on showed holding its own.

Mine broke with IMC and a hard bump of turbulence.

[rbickford]

Hi Fred. Have been looking right at the engine screen when I get the alarm and see no change in the charging rate or the voltage, and it does not change momentarily to be "X"ed out.. Will check out that sensor and bracket. It is a momentary issues so probably not enough time for the G1000 to react and X out the alternator. Thank you

[Lance Murray]

Check these service bulletins and see if one is related to your issue.

http://support.diamond-air.at/fileadmin ... mplete.pdf

http://support.diamond-air.at/fileadmin ... -Wires.pdf

http://support.diamond-air.at/fileadmin ... -009-M.pdf

[rbickford]

Hi Larry. Thank you very much. Very good timing as the issue has gotten a lot worse. Time to stop flying and start fixing.