O-290-D Alternator Conversion

[8337]

Hey guys,

I’m having same problem except I’ve got a c85. How do you test the generator while the engine is running? Ammeter and volt meter ( in cig lighter) both say it’s not.

[8359]

Hey guys,

I’m having same problem except I’ve got a c85. How do you test the generator while the engine is running? Ammeter and volt meter ( in cig lighter) both say it’s not.

The best way I found was to get a multimeter with alligator clips. Locate the power bus underneath the panel and attach the positive lead to it. Attach the negative lead to either the ground bus or to an unpainted section of the frame. The multimeter will read 0V with the master switch off. When you turn on the master, it should read the current battery voltage (12.5-14V depending on the charge). Once you fire up the engine, the voltage will increase slightly. As you rev it to higher RPMs you should see the voltage increase on the multimeter. Over 1000-1200RPM you'll notice a significant change. If you do not see your voltage increase at higher RPM there's a good chance your generator is the culprit.

[6643]

It depends on how much testing you want to do. The easiest thing to do is observe the amp meter. When you start the engine, at idle, the generator will not be charging, your voltage should be battery voltage, and the amp meter will reflect the load. (If nothing's turned on, there should be no load, and the reading should be zero, as it should be if the master is off. If you turn on some loads, like a landing light, you should see a discharge equal to the current draw of the thing you turned on. As you increase engine speed, you should see a sudden change in the amp peter reading, to the right, at the point where the generator voltage comes up to slightly more than the battery voltage. As you continue to increase RPM you should see a positive indication, indicating that the generator is charging the battery.

The amp meter, if correctly wired, should indicate the current into (+) or out of (-) the battery. (It does not indicate starter current.)

If your generator is not charging, the first thing to check is the fuse.

[4004]

Tamer:
Yes batteries "like" to stay full charged - prevents sulfating the plates - which may be the root cause of your situation - your Gill could easily be sulfated and not giving the original capacity, if so, may explain why ,with extended no charge in taxiing and reduced capacity, you are experiencing a low power situation. You didn't spec the battery , G-25, sealed, etc. Suggest you have the battery load tested - under certain FAA operational regs the FAA requires the battery checked each inspection for at least (IIRC) 80% capacity and if you listen to the manufacturers we all should be doing this but I know typically only the major shops have the equipment. When you change the battery, you should consider going to a 35 vs a 25 to get the added capacity, providing your battery box will accommodate or consider the Concord RG-25XC. 2C

[8359]

Tamer:
Yes batteries "like" to stay full charged - prevents sulfating the plates - which may be the root cause of your situation - your Gill could easily be sulfated and not giving the original capacity, if so, may explain why ,with extended no charge in taxiing and reduced capacity, you are experiencing a low power situation. You didn't spec the battery , G-25, sealed, etc. Suggest you have the battery load tested - under certain FAA operational regs the FAA requires the battery checked each inspection for at least (IIRC) 80% capacity and if you listen to the manufacturers we all should be doing this but I know typically only the major shops have the equipment. When you change the battery, you should consider going to a 35 vs a 25 to get the added capacity, providing your battery box will accommodate or consider the Concord RG-25XC. 2C

Sorry, it's a G-25. I looked inside all of the cells and the acid was to the correct level and looked clean. I don't think I did any permanent damage to the battery, thankfully. I'm not sure if my box can fit the G-35, but I wouldn't mind a bigger battery, so maybe I'll upgrade when this one kicks the bucket, or if I do go through with an alternator installation.

Thanks again for the help/feedback.

[8359]

We'll see how this works!

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[8337]

Where is the fuse I need t check?

[6643]

Where is the fuse I need t check?

Who knows? Originally it was in the bottom edge of the panel, just right of center. It may be a circuit breaker if your panel has been updated. It should be labeled "GEN(ERATOR)".

Before you go chasing windmills, what does the amp meter tell you? (If the fuse is blown then you will never show a charge and the needle will not move when you increase RPM.)

[8337]

Mine is all original. I’ve checked every fuse On the panel. Ammeter doesn’t move. It’s on discharge side. How many amps is the fuse I’m looking for.

Plan is to remove generator and voltage regulator and send them to shop. I understand I have to remove tach and replace gasket as well. Gasket must be put on facing correct way or oil will leak.

[6643]

Ammeter doesn’t move. It’s on discharge side.

Do you mean it doesn't move, or it only moves to the discharge side?

How many amps is the fuse I’m looking for.

Depends on the generator. What is the biggest number on the ammeter? The fuse may be the same. Your fuses must be labeled, so now might be a good time to start.

Plan is to remove generator and voltage regulator and send them to shop.

If you have money to burn, that's the way to do it. Otherwise there are plenty of troubleshooting steps you can take first. I'm not sure if they're listed in this forum, but I know they were in the old forum. Search, and if you can't find them I'll write it up and post it again.