Something strange happened - electrical

[Tommy]

Off for a flight today but I have zero power whatsoever when I turn the master on. Well almost no power. When I turned the master on the first time, the gyro whines but very faint. Then nothing at all on the second attempt. 

I flew 2 hours only 3 days ago and prior today no issue at all 14.2 V, ammeter slightly positive. Novoltage warning. Checked the switches all in OFF position. 

Battery fluid all in right level and the battery and alternatorwere both thoroughly inspected last annual 6 weeks ago. I am in a locked but shared hangar. I believe the plane was not tempered. No new electronics on the plane.

What might had happened?

Thanks guys 

Edited September 29, 2017 by Tommy

[Oscar Avalle]

I had a similar problem actually three weeks ago. I turned on the master and no power... but I could hear the click of the relay. First, we thought it would be the relay. We replaced the relay, it worked but when I flew the lights were flickering and it seems that the system was not getting enough power. However, voltage indicator was 14.4 Volts. We looked at it again, and it so happened that it was the bus bar. It was old and they had not done a good job setting up the connections when I upgraded my panel. Now, I have a "new bus bar"... I will be flying tomorrow... will let people know if everything works. 

[takair]

Happened to me two weeks ago...it was a dead gyro.....worn brushes.  On the other hand, I have also had it happen due to a dead battery, they can fail like you described.  How old is it and what type?  Unfortunately, the Gills only seem to last two years in recent years.  Concords tend to do better.

[Tommy]

I think it's a concord but very old (5 years)

But is this a symptom of a dying battery? Can it fail so catastrophically and suddenly without warning? 

I have no work done on the electrical system at all. Hmmm...

 

Edited September 29, 2017 by Tommy

[DonMuncy]

You didn't leave (or accidentally turn) on the cabin light, did you.

[Tommy]

Nope nothing. I double checked. I wonder if someone was playing with my plane? The hangar gremlins! But the throttle has a lock on it. 

[DonMuncy]

One of my theories of life is that batteries have an agenda of their own and can fail whenever they darn well please. This may be one of those times. 

[Tommy]

Jump wire on and all system normal so it must be the battery or something is draining it! Going to jump start it and run for few hours to see if I can get it charged up 

[ArtVandelay]

1 hour ago, Tommy said:

I think it's a concord but very old (5 years)

But is this a symptom of a dying battery? Can it fail so catastrophically and suddenly without warning? 

I have no work done on the electrical system at all. Hmmm...

 

yes, batteries can short out internally, and they die a quick death. Check the voltage of your battery.

[Tommy]

1 hour ago, teejayevans said:

yes, batteries can short out internally, and they die a quick death. Check the voltage of your battery.

I see. Ok got it jump started Amp.megre reads 30 plus now normal after 100 minutes of flying. 

If it has shorted, will it follow that the problem will be reproducible with few days of not flying?

 

[Pritch]

Sounds like a similar problem my boss had with a Seneca a couple of weeks ago.  The pilot few the plane to another field, got back in and it would not start. Battery was fine, put in another solenoid, turned on the master and it clicked.  Turned it of and back on and nothing. the boss had put a meter on the master switch when we first got there and it was fine.  Ended up jumping the solenoid and everything worked.  It was flown back to the shop and master switch was pulled out and had burn marks on a couple of the poles. New switch and everything works fine.

Pritch

[Tommy]

Think I found the culprit! For some reason the switch was set to Dim! My pax last flight must had bumped it! 

[ArtVandelay]

I see. Ok got it jump started Amp.megre reads 30 plus now normal after 100 minutes of flying. 
If it has shorted, will it follow that the problem will be reproducible with few days of not flying?
 

Batteries that die, stay dead, so yes the problem will be reproduced, It will lose power as it rests. You need a digital multimeter. Just after flying it should be around 12.8v, you can disconnect the + side, put the multimeter (ammeter function) in series and double check there is no drain on the battery with the master off. As this point it could be bad battery, a cargo light left on, a bad relay not opening when master is off, more diagnostics are required.

[Jim F]

I pulled all of the bulbs out do it can't happen. 

[Piloto]

24 minutes ago, Tommy said:

Think I found the culprit! For some reason the switch was set to Dim! My pax last flight must had bumped it! 

This happened to me so I modified the overhead lights. The lights are connected directly to the battery bypassing the battery relay so they will drain the battery even with the master OFF. I switch the lights supply point to that of the stall warning at the overhead interior plastic. Easy to do through the right speaker panel. Now when the master is OFF the overhead lights will be OFF even if their rocker switch is ON.

José 

 

[bradp]

Mine have also been modified - they will only turn on if the master is on. 

Look up Eric the car guy parasitic battery drain. It’s Auto but a good explanation and some general principles of how to find things that kill batteries apply.

Link : 

 

[DonMuncy]

10 hours ago, Piloto said:

This happened to me so I modified the overhead lights. The lights are connected directly to the battery bypassing the battery relay so they will drain the battery even with the master OFF. I switch the lights supply point to that of the stall warning at the overhead interior plastic. Easy to do through the right speaker panel. Now when the master is OFF the overhead lights will be OFF even if their rocker switch is ON.

José 

 

Or you could have your hangar elf install a timer, and they will shut off automatically.

[HRM]

2 hours ago, bradp said:

Look up Eric the car guy parasitic battery drain. It’s Auto but a good explanation and some general principles of how to find things that kill batteries apply.

If you are in a hurry (Eric tends to be wordy) try here. 

With a Mooney, the test should be fairly straightforward, but it helps to know the electrical system. There could be something not on a breaker, but with a fuse somewhere.

[ArtVandelay]

Or you could have your hangar elf install a timer, and they will shut off automatically.

Be aware the timer circuitry will draw a small amount of current even if lights are off, probably on the order of 10mA, should not be a problem unless you are storing your plane for the winter.

[DonMuncy]

8 hours ago, teejayevans said:

Be aware the timer circuitry will draw a small amount of current even if lights are off, probably on the order of 10mA, should not be a problem unless you are storing your plane for the winter.

I am not an electronic genius, but I am pretty sure mine does not. My timer is powered through the master switch, which then activates a relay fed by the circuit that ordinarily feeds the cabin light. When the master is turned off, the circuitry holds the relay energized for about 11 minutes, at which time, it opens. My belief is, that at that time the cabin light circuit stops drawing current. Am I wrong?

[HRM]

3 hours ago, DonMuncy said:

I am not an electronic genius, but I am pretty sure mine does not. My timer is powered through the master switch, which then activates a relay fed by the circuit that ordinarily feeds the cabin light. When the master is turned off, the circuitry holds the relay energized for about 11 minutes, at which time, it opens. My belief is, that at that time the cabin light circuit stops drawing current. Am I wrong?

The relay opens the cabin light circuit so that regardless of the state of the light switch, it goes off. The question remains: what powers your relay or the circuitry that holds the relay on during the delay? That circuit may continue to draw power and thus be parasitic. If it is electromechanical, then it might shut off completely after the delay.

[DonMuncy]

39 minutes ago, HRM said:

The relay opens the cabin light circuit so that regardless of the state of the light switch, it goes off. The question remains: what powers your relay or the circuitry that holds the relay on during the delay? That circuit may continue to draw power and thus be parasitic. If it is electromechanical, then it might shut off completely after the delay.

With my limited electric/electronic knowledge; When power is provided to the timer, it charges a capacitor. When the power is removed (via the master switch), the charge in the capacitor bleeds off through a resistor. When the capacitor charge drops low enough, the power is removed from the relay (which is electromechanical), so no more power is consumed: I think!

[ArtVandelay]

With my limited electric/electronic knowledge; When power is provided to the timer, it charges a capacitor. When the power is removed (via the master switch), the charge in the capacitor bleeds off through a resistor. When the capacitor charge drops low enough, the power is removed from the relay (which is electromechanical), so no more power is consumed: I think!

Do you have a schematic or photo?

[DonMuncy]

14 hours ago, teejayevans said:

Do you have a schematic or photo?

If you need further info on my timer, let me know.

Final timer circuit.doc

[HRM]

13 hours ago, DonMuncy said:

schematic

You have two paths to ground from the battery through your transistors that will contribute to parasitic battery drain. The good news is that the reverse saturation (leakage) current for a 2N2222 is going to be in nano amperes.