Electrical Issue

[Mooney1]

During run up yesterday (68G) and noticed a slight discharge on the Amps gauge (-10). No warning light installed. No breaker popped. So I recycled the Alt breaker and the gauge indicated a +40 for about a second or two then returned to a negative reading.

Thoughts?

Edited July 14, 2021 by Mooney1
Photos added

[David Lloyd]

Based on that alone, either a failing voltage regulator or alternator, but probably the regulator.

[Raymond J1]

A current consumption greater than the load flow rate... But the charge works since you get 40 A A short time. I suggest you check the masses and setting the regulating voltage of the regulator. If OK for both, see the state of the brushes or the inductor of the generator / alternator. If not OK, check the regulator.

Edited July 14, 2021 by Raymond J

[Marauder]

2 hours ago, Mooney1 said:

During run up yesterday (68G) and noticed a slight discharge on the Amps gauge (-10). No warning light installed. No breaker popped. So I recycled the Alt breaker and the gauge indicated a +40 for about a second or two then returned to a negative reading.

Thoughts?

Start with the simple things. Look to make sure the wiring is snug and not shorting. I think there is a shunt in the system. Voltage regulator is high on the suspect list of probably causes. When my voltage regulator failed, I didn't see spikes like this, just low amps.

 

[chriscalandro]

Did you check your voltage?  That’s step one. 
 

it’s not possible to know the answer or to even make a educated guess without knowing this information. 
 

hell, it could just be the gage. 

[Mooney1]

Thanks for the ideas. Went out to troubleshoot this morning and everything worked normally. Weird!! Found 1 wire that looked like it needed some help so will remedy that and replace the voltage regulator.

 

Thanks

[chriscalandro]

1 minute ago, Mooney1 said:

Thanks for the ideas. Went out to troubleshoot this morning and everything worked normally. Weird!! Found 1 wire that looked like it needed some help so will remedy that and replace the voltage regulator.

 

Thanks

It’s silly to replace the regulator when you don’t know that it’s bad. 
 

there is an airplane on my field that had the same problem. The amp meter read low. He spent 1200$ replacing the alternator and regulator only to find the gauge was just reading wrong. 
 

check your voltage.  

[Mooney1]

3 minutes ago, chriscalandro said:

It’s silly to replace the regulator when you don’t know that it’s bad. 
 

there is an airplane on my field that had the same problem. The amp meter read low. He spent 1200$ replacing the alternator and regulator only to find the gauge was just reading wrong. 
 

check your voltage.  

Checked the voltage on the meter earlier. Not really that silly to replace something that is 53 years old.

 

Thanks

[chriscalandro]

And what was the voltage?  
 

It is if it isn’t broken. 

[PT20J]

5 hours ago, Mooney1 said:

During run up yesterday (68G) and noticed a slight discharge on the Amps gauge (-10). No warning light installed. No breaker popped. So I recycled the Alt breaker and the gauge indicated a +40 for about a second or two then returned to a negative reading.

Thoughts?

This description is typical behavior if the over voltage protector trips.

[David Lloyd]

I gave you kind of a short answer this morning, sorry about that.  I'm guessing you sold N3435N and now have a 1968 G model. Right about that time, some planes still had the generator, a alternator was optional.  Many generators were replaced in the past with Interav alternator conversions, and more recently Plane Power alternators, now bought by Hartzell.  So, what do you have?  Several good suggestions and observations have been made by others.  Loose and broken wiring, overvoltage trip (especially with the Interav), faulty switch, dirty connections, worn brushes, etc.

Your description of noticing a discharge (15 amps would be the load roughly for a few radios, beacon, or strobe) cycling the breaker and the system coming back to life for a bit.  The 40 amp load was just covering the equipment load plus charging the battery after it depleted a bit from starting the engine and running the equipment without the charging system working.

Did you have a hard time starting the engine and run down the battery prior to that happening?  Occasionally that will cause something to trip, usually the main breaker.  I have had experience with several Interav overvoltage relays tripping for an undetermined cause.  Let us know what you have, and what wire looked a bit iffy.  Sometimes this stuff just happens then goes away, but usually not.  Some more info please.

[Mooney1]

3 hours ago, David Lloyd said:

I gave you kind of a short answer this morning, sorry about that.  I'm guessing you sold N3435N and now have a 1968 G model. Right about that time, some planes still had the generator, a alternator was optional.  Many generators were replaced in the past with Interav alternator conversions, and more recently Plane Power alternators, now bought by Hartzell.  So, what do you have?  Several good suggestions and observations have been made by others.  Loose and broken wiring, overvoltage trip (especially with the Interav), faulty switch, dirty connections, worn brushes, etc.

Your description of noticing a discharge (15 amps would be the load roughly for a few radios, beacon, or strobe) cycling the breaker and the system coming back to life for a bit.  The 40 amp load was just covering the equipment load plus charging the battery after it depleted a bit from starting the engine and running the equipment without the charging system working.

Did you have a hard time starting the engine and run down the battery prior to that happening?  Occasionally that will cause something to trip, usually the main breaker.  I have had experience with several Interav overvoltage relays tripping for an undetermined cause.  Let us know what you have, and what wire looked a bit iffy.  Sometimes this stuff just happens then goes away, but usually not.  Some more info please.

Yes, I sold 35N March of last year and have missed it everyday. I have acquired a G that I have just finished restoring. Voltage regulator on order and one wire was noticed suspect. 
 

[chriscalandro]

Get a new alternator while your at it

[MikeOH]

Why are you shotgunning this, rather than troubleshooting?

[chriscalandro]

2 hours ago, MikeOH said:

Why are you shotgunning this, rather than troubleshooting?

Because clearly random people on the internet making baseless suggestions is waaayyyy better than actually doing any amount of work to figure out the real problem. 
 

But hey, there’s about a 25% chance he will get it on the first shot. 

Edited July 15, 2021 by chriscalandro

[Ragsf15e]

Even if you just get an inexpensive voltage gauge that goes into your cigarette lighter, it’s good to know the voltage.  If you notice a discharge but you’re still seeing 14v, that probably means something different than discharge with 12v.  You really shouldn’t see 40amps as the amperage is the amperage going to/from the battery, not the amperage running everything that’s on.

Edited July 15, 2021 by Ragsf15e

[carusoam]

Things to consider for this situation…

1) Which alternator or generator do you have?

2) Which voltage regulator is controlling it?

3) How many volts is the USB / voltage meter showing in the cigarette lighter?

4) how many rpm were you running while making this observation?

5) Generators don’t make much output until rpms are really high….  So most start-up and taxi Time is slowly draining the battery….  When the rpms come up, old style VRs tend to try and charge the battery as quickly as possible…

6) Alternators are only a touch better… by the time they are adding electrons to the battery, you are speeding on the taxi way, or dragging the brakes…

7) If all original equipment, and you fly in IMC… Swapping out the old for the new has a ton of value…

8) Go easy on Chris… he hasn’t figured out MSers aren’t random people on the internet… we have been the same people hazing him for years…   

PP thoughts only, stuff I read around here… 

Best regards,

-a-

[chriscalandro]

3 hours ago, Ragsf15e said:

Even if you just get an inexpensive voltage gauge that goes into your cigarette lighter, it’s good to know the voltage.  If you notice a discharge but you’re still seeing 14v, that probably means something different than discharge with 12v.  You really shouldn’t see 40amps as the amperage is the amperage going to/from the battery, not the amperage running everything that’s on.

If you spend some time with a draw on the battery and then turn on the alternator it will probably initially pull 40-45 amps until the battery gets some charge in it. 
 

this is one of the reasons it might not be a real thing as the original poster stated it read 40 amps for a second or 2, suggesting that the battery was charged and not actually discharging at all except the brief moment he did the test.

 

But what do I know, I’m just a simple electrical engineer. 

Edited July 15, 2021 by chriscalandro

[Yetti]

On 7/14/2021 at 9:08 AM, Marauder said:

Start with the simple things. Look to make sure the wiring is snug and not shorting. I think there is a shunt in the system. Voltage regulator is high on the suspect list of probably causes. When my voltage regulator failed, I didn't see spikes like this, just low amps.

 

This

[Mooney1]

Thanks for the input!! Replaced the VR system working great. 14.2v all day long.

[carusoam]

Great follow up M1!

Did you go with a Zeftronics unit?

Best regards,

-a-

[Mooney1]

11 hours ago, carusoam said:

Great follow up M1!

Did you go with a Zeftronics unit?

Best regards,

-a-

Yes I went with Zeftronics. 

[Marauder]

Yes I went with Zeftronics. 

I went with Zeftronics as well. Really like the stability of its regulation. Rock solid at 14.1 volts.


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