Atomic 4 Alternator Failure

[RMEASON]

I have an Atomic 4 Alternator Failure with symptoms below:

-Engine starts and runs with no noticeable issues.
-Engine runs until Battery 1 is dead. (3 to 3-1/2 hours)
-Engine runs with combined 1+2 Battery it will run until both are dead. 7-1/2 hours.

No measurable output from the Alternator (Less than 2 years old)

The alternator was a Single Wire Internal regulated unit.

Is there a fuse in the ignition/exciter circuit?

What would cause this?

rmeason

[Al Schober]

Those single wire alternators are pretty simple. Connect them to the battery, spin them, they make current. So first questions is: what voltage do you measure at the alternator output? If same as the battery, the alternator isn't doing it's thing.
If you're confident in your abilities, you can dig into it yourself. Recommend you take it to an alternator shop and have it checked. The internal regulator may be fried.

[ndutton]

I have a 105A Delco 10Si single wire alternator and have had it apart replacing the regulator (no reg failure, just taming down the output voltage) and adding an AC tap for the tachometer. There is no fuse or other overcurrent protection inside.

You do know:

1. The alternator needs a battery connected to work.
2. The alternator needs to spin up to roughly 1000 engine RPM (1700 alternator RPM approx.) to start producing. After it starts it will continue producing at lower RPM down to idle but it needs to be goosed to get it going.

[joe_db]

Those single wire alternators are pretty simple. Connect them to the battery, spin them, they make current. So first questions is: what voltage do you measure at the alternator output? If same as the battery, the alternator isn't doing it's thing.
If you're confident in your abilities, you can dig into it yourself. Recommend you take it to an alternator shop and have it checked. The internal regulator may be fried.

Replacing the regulators is pretty easy and they are cheap, but if you aren't up for it definitely take it to a shop.

[RMEASON]

Alternator Follow Up.

Those single wire alternators are pretty simple. Connect them to the battery, spin them, they make current. So first questions is: what voltage do you measure at the alternator output? If same as the battery, the alternator isn't doing it's thing.
If you're confident in your abilities, you can dig into it yourself. Recommend you take it to an alternator shop and have it checked. The internal regulator may be fried.

I tested the alternator using the following method:

-Tested battery voltage before starting engine. (12.87 volts)
-Started Engine
-Throttle to 1000 RPM
-Re Tested battery voltage at both battery terminal and on Alternator (12.87 volts)
-After running for 30 minutes tested voltage (12.47 volts at both battery and alternator)

Pulled the alternator and took it to auto zone. They put it on their machine and got a fail. I have a new alternator and want to make sure I don't damage it when installing. I cannot get any info on the actual voltage that should flow from the Exciter Wire to the positive coil?

[joe_db]

I tested the alternator using the following method:

-Tested battery voltage before starting engine. (12.87 volts)
-Started Engine
-Throttle to 1000 RPM
-Re Tested battery voltage at both battery terminal and on Alternator (12.87 volts)
-After running for 30 minutes tested voltage (12.47 volts at both battery and alternator)

Pulled the alternator and took it to auto zone. They put it on their machine and got a fail. I have a new alternator and want to make sure I don't damage it when installing. I cannot get any info on the actual voltage that should flow from the Exciter Wire to the positive coil?

If you have a single-wire alternator, there is no connection to the coil nor is there an exciter wire.

[RMEASON]

Alternator Follow Up Is the Exciter Wire Needed?

New 55 Amp Alternator Instructions: Single Output/Internal Regulation.

GENERAL: Your new API Alternator is internally regulated with a single output terminal, very similar to the original
Motorola alternator used on the Atomic 4 for many years. There are only two terminals which you will need to understand to install your new alternator: The OUTPUT terminal, and the EXC terminal.
OUTPUT TERMINAL: The output terminal is the terminal next to the letter B next to it on the housing. The output terminal should be connected to the battery bus in the very same way that your original Motorola was connected, usually
by an orange 8 gauge wire that connects to the ammeter.
If you do not have an ammeter, or the ammeter does not work, you can connect the output terminal of the API directly
to the big battery cable on the starter solenoid. When connected in this fashion, you can monitor the alternator performance by installing a volt meter in the cockpit (in place of the ammeter) and simply connect the voltmeter to any reliable source of DC power, usually directly from the ignition switch. A volt meter does not need to be connected in series
with the output of the alternator, so the heavy gauge wire that originally ran from the alternator to the ammeter, is unnecessary.
EXC TERMINAL: "Connect the EXC terminal to the positive terminal of the coil using a 14 gauge wire so that the fields
of the alternator will be excited when the ignition switch is turned on."
MoyerMarineinc.
PARTS
Connecting your new
12v 55amp API alternator
www.moyermarine.com • 717-766-877

[joe_db]

New 55 Amp Alternator Instructions: Single Output/Internal Regulation.

GENERAL: Your new API Alternator is internally regulated with a single output terminal, very similar to the original
Motorola alternator used on the Atomic 4 for many years. There are only two terminals which you will need to understand to install your new alternator: The OUTPUT terminal, and the EXC terminal.
OUTPUT TERMINAL: The output terminal is the terminal next to the letter B next to it on the housing. The output terminal should be connected to the battery bus in the very same way that your original Motorola was connected, usually
by an orange 8 gauge wire that connects to the ammeter.
If you do not have an ammeter, or the ammeter does not work, you can connect the output terminal of the API directly
to the big battery cable on the starter solenoid. When connected in this fashion, you can monitor the alternator performance by installing a volt meter in the cockpit (in place of the ammeter) and simply connect the voltmeter to any reliable source of DC power, usually directly from the ignition switch. A volt meter does not need to be connected in series
with the output of the alternator, so the heavy gauge wire that originally ran from the alternator to the ammeter, is unnecessary.
EXC TERMINAL: "Connect the EXC terminal to the positive terminal of the coil using a 14 gauge wire so that the fields
of the alternator will be excited when the ignition switch is turned on."
MoyerMarineinc.
PARTS
Connecting your new
12v 55amp API alternator
www.moyermarine.com • 717-766-877

That isn't single-wire. It does accurately describe how to hook up an alternator that needs an on signal.

[ndutton]

Connecting a true single wire alternator as described may cause the engine to continue running when the key switch is turned off. I had an internal regulator replaced by a reputable shop and without asking they generously added an excite wire so the single wire alternator would jump to life without the initial RPM bump. The unintended consequence was the self excite circuitry inside the alternator energized the excite wire resulting in a 12V backfeed to the coil.

First time I tried it I couldn't shut the engine off, wound up pulling the choke. Connecting the excite wire to the solenoid R terminal (energized only while the starter was engaged) worked pretty well but later on I abandoned the redundant excite wire because it was totally unnecessary. It's not that hard to bump the RPM on start up.

[joe_db]

Connecting a true single wire alternator as described may cause the engine to continue running when the key switch is turned off. I had an internal regulator replaced by a reputable shop and without asking they generously added an excite wire so the single wire alternator would jump to life without the initial RPM bump.

First time I tried it I couldn't shut the engine off, wound up pulling the choke. I then connected the excite wire to the solenoid R terminal (energized only while the starter was engaged) and it worked pretty well but later on I abandoned the redundant excite wire because it was totally unnecessary.

The other fix is to add a diode so current only goes from coil to alternator and not the other way

[RMEASON]

Alternator Follow Up.

That isn't single-wire. It does accurately describe how to hook up an alternator that needs an on signal.

Installed new API alternator and it works perfectly? Nothing different or changed. Must be gremlins?