Bad Generator or Bad Battery

gitmo234

gitmo234

Line Up and Wait
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gitmo234
Interesting flying today. The wife and I flew about an hour up to the Philadelphia area. Flight there was uneventful. Had dinner with a friend I havent seen in over a year. He and his 4 year old son had never been in a small airplane before so we hopped and I took him on 3 trips in the pattern and shut her down.

We chatted a bit, said our goodbyes and hopped in the airplane...click click click.... the prop would barely turn over. It wasnt going to start.

Double checked everything went through the checklists a few times...still nothing. The airport closed early, nobody was around. I called my friend back and had him bring some jumper cables. I have never hand propped an airplane and I wasnt about to try without someone who was experienced teaching and I certainly wasnt letting my wife try.

We jumped the airplane just like you would a car (thank god the older cessnas had a gigantic cowling door with easy access. Once the engine started, I shut it down, disconnected everything, cleared the area, and she started again a bit sluggishly. I was in an a transponder required area, so the plan was to fly until out of that area and shut off all avionics until I was sure I could get home before dark and wouldnt need power to turn on the radios so I could access the lights.

Once I got up I realized we had plenty of time...more than an hour until sunset, and even then plenty of light to spare, so I kept the avionics on because I was reading a charge on the gauge. The radios sounded "grainy" here and there, rougher than usual, but the avionics stayed on for an hour flight without issue (other than sounding grainy) and I radio checked clearly with some distant flyers, all gave me LC.

So once on the ground I talked it over with another pilot I ran into, he said it sounded like I may have a bad battery vs a bad generator, the battery may just not be holding a charge.

Anyone else experience similar and have any input?
 
Check the voltage wth the engine running (plug a volt meter into the cigaretter lighter). For a 12 V system, it should read about 14V. For a 24 V system, it should read about 28V. If it does, the alternator is working.
 
Graueradler said:
Check the voltage wth the engine running (plug a volt meter into the cigaretter lighter). For a 12 V system, it should read about 14V. For a 24 V system, it should read about 28V. If it does, the alternator is working.
Click to expand...

Thanks, I'll give it a try. My airplane is a 56, so it has a generator vs an alternator...same readings I assume?

If it was a battery or the generator going, any chance this would have an effect on older radios? A month ago my com 2 stopped working. When I put it to test it creates static but doesnt transmit or pick up anything. Was wondering if voltage irregularity due to something failing would cause it. Its a very old radio.
 
I'd do the easy stuff first, test the battery IAW the battery ICAs, if it passes try cleaning the comutator of generator.

then place a load on the generator, and see if it will produce full amperage.
 
I had a 60 with gen. It didn't go out all at once but just didn't purchase out enough amps. New brushes fixed it right up. By the way, when my battery went bad it wouldn't do much of anything. I hand propped it quite often. Started very easy. Easiest way to check battery is to put battery charger on battery overnight. When you take off see if it will turn over. Then let set day or two and go back again and see if it turns over. If not, it's battery
 
You can do a quick check on the state of charge of your battery with a volt meter. This should be done after fully charging and the battery has sat undisturbed (no load or charge) for a period of 24 hrs. This will not tell you everything about the general state of your battery but if it's not 100% it will tell you there is a problem.

Battery_Charge.jpg
 
Went to the airplane today and it started right up, and com 2 worked. Draw from the cigarette lighter plug was 11.5 but was told by a local that a generator won't have the same read as an alternator. Did some reading in servicing an aviation battery and charging it. I'm wondering if I just didn't do something stupid and kill the battery. I have a trickle charger than is below 10 amps as I've read is recommended. I'm gonna charge it and see how it goes
 
Disregard my last post. I had someone who actually is an electrical engineer take a look. Power port is indicating 11.5, battery at the terminal is 11.75. I show either a neutral charge or slight discharge on ammeter until I'm at 2000 rpm or more, suspected voltage regulator. Or it's so damn old (1956) and that was somewhat common then, allegedly
 
Could be battery, generator, corroded battery posts, regulator, bad connection somewhere.

Get your '56 Chevy shop manual out and follow the trouble shooting chart there.
 
gitmo234 said:
Interesting flying today. The wife and I flew about an hour up to the Philadelphia area. Flight there was uneventful. Had dinner with a friend I havent seen in over a year. He and his 4 year old son had never been in a small airplane before so we hopped and I took him on 3 trips in the pattern and shut her down.

We chatted a bit, said our goodbyes and hopped in the airplane...click click click.... the prop would barely turn over. It wasnt going to start.

Double checked everything went through the checklists a few times...still nothing. The airport closed early, nobody was around. I called my friend back and had him bring some jumper cables. I have never hand propped an airplane and I wasnt about to try without someone who was experienced teaching and I certainly wasnt letting my wife try.

We jumped the airplane just like you would a car (thank god the older cessnas had a gigantic cowling door with easy access. Once the engine started, I shut it down, disconnected everything, cleared the area, and she started again a bit sluggishly. I was in an a transponder required area, so the plan was to fly until out of that area and shut off all avionics until I was sure I could get home before dark and wouldnt need power to turn on the radios so I could access the lights.

Once I got up I realized we had plenty of time...more than an hour until sunset, and even then plenty of light to spare, so I kept the avionics on because I was reading a charge on the gauge. The radios sounded "grainy" here and there, rougher than usual, but the avionics stayed on for an hour flight without issue (other than sounding grainy) and I radio checked clearly with some distant flyers, all gave me LC.

So once on the ground I talked it over with another pilot I ran into, he said it sounded like I may have a bad battery vs a bad generator, the battery may just not be holding a charge.

Anyone else experience similar and have any input?
Click to expand...
Your mechanic has had similar experiences. Contact him.
 
My annual is coming up at the end of next week. I'm probably going to roll that into it. In the mean time I can deal with the occasional charging of the battery. Avionics all work fine in flight with out too much degradation.

Once I'm up in flight the ammeter indicates a slight charge the entire flight.. I only have 1 or two flights coming up so I should be okay
 
Jim,

Do you say that because you know my mechanic? He helped me with some troubleshooting on the phone when I was stuck for a bit, and he's going to take a look at it this week. I posted on here because someone may have some advice (like what I've gotten above) that could have potentially identified it as a simple problem that I could fix vs something large.


BTW to the rest, I actually took it up last night a bit. Started just fine, went up for about 30 minutes, it registered a charge on the ammeter for the duration of the flight (normal in my experience with this airplane). Got it down, put some fuel in it to up for a bit longer, and it wouldnt crank. Tried three times. Got out for a second to consider a push and see if anyone could help. Decided to give it one more shot, pulled the starter and it cranked right up.
 
gitmo234 said:
Got it down, put some fuel in it to up for a bit longer, and it wouldnt crank. Tried three times. Got out for a second to consider a push and see if anyone could help. Decided to give it one more shot, pulled the starter and it cranked right up.
Click to expand...

Now, that's starting to sound like old and oxidized contactors (master and starter solenoids), or a bad starter switch on the starter itself. It's the old pull-start, right? No starter contactor, but a heavy switch on the starter that the lever actuates.

Dan
 
Thanks Dan. For all i know it could be a combo of both. I'm beginning to suspect this may be stupid pilot induced.

It is an old pull starter (conversion to push button is on my list eventually). Prior to all this, on my flight to camden county NJ, I was up about 20 minutes into the flight and realized the pull starter was about halfway out, so it could have been engaged. Maybe damaged the starter.

I think there is something going on with the power though, with my low readings and occasional "grainy" sound on the intercom. In another oddity, my com 2 has come back alive, although it sounds like garbage, it at least works

EDIT: wanted to add that my checklists are custom made because the aircraft manual checklists are about 5 lines a piece, I added a few extra common sense checks. I'm now going to add it "ensure starter is fully forward - actually look at it, idiot" to the checklist.
 
gitmo234 said:
Disregard my last post. I had someone who actually is an electrical engineer take a look. Power port is indicating 11.5, battery at the terminal is 11.75. I show either a neutral charge or slight discharge on ammeter until I'm at 2000 rpm or more, suspected voltage regulator. Or it's so damn old (1956) and that was somewhat common then, allegedly
Click to expand...
Generators don't charge much at low speeds - not like a modern alternator.
What voltage did you get when you had the engine up to speed?

Could be the regulator or could be worn brushes or...
 
It stayed the same up to 1800, didn't test in-flight at 2200 or above. I'll see if I can do that later today
 
First off, inspect all the bonding/grounding straps. You should be able to trace a definite ground around the motor mounts, typically through a bare braiding strap, although a cable is perfectly fine. If that bonding strap is corroded, that will screw up your system.

If that's good, pull the battery, put it on a charger, charge it, do a load test on it (any auto parts store has the machine and do it free) see what it says. If you are taking a hand held meter and metering 11.5 volts on the battery posts, I suspect you have a bad battery, but the above test will tell you.

If the battery tests good and you have a generator, I would inspect the brushes and commutator next, your local Auto Electric (or tractor repair) shop can handle that, as well as testing the voltage regulator. You're looking at between $15 and $175 (or the price of a battery if higher) depending on what is wrong.
 
Henning said:
First off, inspect all the bonding/grounding straps. You should be able to trace a definite ground around the motor mounts, typically through a bare braiding strap, although a cable is perfectly fine. If that bonding strap is corroded, that will screw up your system.

If that's good, pull the battery, put it on a charger, charge it, do a load test on it (any auto parts store has the machine and do it free) see what it says. If you are taking a hand held meter and metering 11.5 volts on the battery posts, I suspect you have a bad battery, but the above test will tell you.

If the battery tests good and you have a generator, I would inspect the brushes and commutator next, your local Auto Electric (or tractor repair) shop can handle that, as well as testing the voltage regulator. You're looking at between $15 and $175 (or the price of a battery if higher) depending on what is wrong.
Click to expand...

Thank you! Glad to see you back
 
gitmo234 said:
Jim,

Do you say that because you know my mechanic? He helped me with some troubleshooting on the phone when I was stuck for a bit, and he's going to take a look at it this week. I posted on here because someone may have some advice (like what I've gotten above) that could have potentially identified it as a simple problem that I could fix vs something large.


BTW to the rest, I actually took it up last night a bit. Started just fine, went up for about 30 minutes, it registered a charge on the ammeter for the duration of the flight (normal in my experience with this airplane). Got it down, put some fuel in it to up for a bit longer, and it wouldnt crank. Tried three times. Got out for a second to consider a push and see if anyone could help. Decided to give it one more shot, pulled the starter and it cranked right up.
Click to expand...

No. I said it because I've flown for 45 years and have been stranded twice by electrical problems that I " doped out myself". In both cases, they " solved themselves" until they didn't. One was a bad switch, the other a dead short. I could not have fixed them myself regardless of Internet " advise". Good luck.
 
gitmo234 said:
I think there is something going on with the power though, with my low readings and occasional "grainy" sound on the intercom. In another oddity, my com 2 has come back alive, although it sounds like garbage, it at least works
Click to expand...

Such noise in the headset is often due to a worn or failing commutator in the generator, which is usually accompanied by worn-out brushes. And a modern Com is often fussy about system voltage, which could be dropping as the generator fails.

Best to convert to an alternator.

Dan
 
Dan- thanks! That's what my mechanic was indicating. Can't wait for him to take a look. I've been up In it a couple time since. The issue seems to more accurately be that it doesn't like to crank warm. Ran it today, it cranked over like always, past all checks, at higher RPM, reading 12v or just over at the power port.

Killed it and about 5 minutes later realized I wanted to do a com check as well.... It wouldn't crank.

Waited 5-10 more minutes, when I heard everything had stopped, then it cranked right up.
 
Fat Albert has generators. I pull em myself about every 5 years to replace the brushes and lightly polish the commutator. Then take them to PEP Boys to be checked on their machine. I always tell them it is off a 56 Ford. They get all excited over that.
One time at the annual after going through the logs the mechanic commented that he had never seen generator brushes last that long. I just shrugged. He did have to overhaul one of the voltage regulators a few years back and adjust the change over relays. It seemed to make him happy that something finally failed and he hasn't mentioned the brushes since.. Come to think of it, I'm about due to change them again..
 
Thanks Tom. I'll report back to everyone what the A&P digs up.
 
Theboys said:
I don't think it is so easy or very cheap to convert a 0-300 to alt.
Click to expand...

Yep, it's about a grand, Drain the oil, remove the generator, remove the drive from it, install it on the alternator, install the alternator, remove the old voltage regular, install the voltage controller for the alternator, run two wires, hook it up, and your good to go.

OBTW it stops the oil leak too.
 
Last edited:
Airplane has hit the annual and they started by taking a look at this. Preliminary reports:

1) screw was missing from the starter, the other had vibrated loose and was hand turnable. Mechanic was surprised I could even get it started based on that.

2) Voltage regulator is brand new and adjusting it didnt do much so they played with the generator some, and discovered it simply wasnt able to put out the power needed. They're going to see if its the brushes and if so replace that.

A decision on upgrading to the alternator will be made based on the rest of the annual and how that looks
 
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