One Wire Alternator Maxed Out

[Ricks70Duster340]

As soon as the engine starts my voltmeter goes to ~14.6 and stays there. Occasionally I will see it dip just a bit but goes right back up. I had one alternator go bad after a short time and am concerned about the new one doing the same. Hoping someone can steer me to what may be loading it down like this.

This is a 100A one wire alternator on my 72 Challenger with a trunk mounted battery. I have a 0/2 positive wire going to a connection block in the engine compartment that splits to the starter & different smaller loads. I am using a 0/2 ground cable that goes to the frame rail at the trunk. There is a smaller ground cable that goes from the negative terminal on the battery to the trunk lid support. I have several ground wires at different areas in the engine compartment.

I am running two HDX 13" electric fans through relays and the relays are connected directly to the alternator battery terminal. I am also running a 6# wire from the alternator to the starter relay through a fuse. The other connections to the alternator battery terminal are headlight relays & the OE style battery connection that goes to the firewall connection.

 

[67Dart273]

The default V for a properly warmed and charged battery as well as warmed VR is 13.8--14.2, so .4V high is not tremendous, at all. I don't suppose whatever this is has an optional "sense" terminal? You might get ahold of the manufacturer.

Also, voltage does not equal high charge rate. You have no idea with a voltmeter, WHAT the current is doing. If the battery is quite discharged, or has a problem, like sulfated, the alternator might be working it's pants off, but it might just be floating. A voltmeter will never tell you that

"Rig" an ammeter for testing, and nowadays you can buy clamp on ones for DC. MUST be for DC. You can also listen, is it grunting/ singing hard and loud? Is the output terminal/ charge wire quite warm? Does the alternator run hot, hotter than seems normal?

 

[Kendog 170]

I ran my Alt. power wire to my Battery in trunk and then up to the relay. My sense wire is at the relay. I'm not saying that's your issue though. Do you have a sense wire? I run a Denso

 

[Ricks70Duster340]

The default V for a properly warmed and charged battery as well as warmed VR is 13.8--14.2, so .4V high is not tremendous, at all. I don't suppose whatever this is has an optional "sense" terminal? You might get ahold of the manufacturer.

Also, voltage does not equal high charge rate. You have no idea with a voltmeter, WHAT the current is doing. If the battery is quite discharged, or has a problem, like sulfated, the alternator might be working it's pants off, but it might just be floating. A voltmeter will never tell you that

"Rig" an ammeter for testing, and nowadays you can buy clamp on ones for DC. MUST be for DC. You can also listen, is it grunting/ singing hard and loud? Is the output terminal/ charge wire quite warm? Does the alternator run hot, hotter than seems normal?

Thanks. No noise coming from the alternator. After the original alt failed I removed the bypass wire (was going over the engine-to firewall-to starter relay). Not sure what the gauge was but I put on a larger 6# and ran it across the front. Saved a few feet of length doing that. Good idea about the DC clamp test.

 

[Ricks70Duster340]

I ran my Alt. power wire to my Battery in trunk and then up to the relay. My sense wire is at the relay. I'm not saying that's your issue though. Do you have a sense wire? I run a Denso

No sense wire on this. It is a CVF Mopar alternator.

Black Chrysler 1 Wire Alternator, 100 Amp, 8-Rib Serpentine Pulley

The default V for a properly warmed and charged battery as well as warmed VR is 13.8--14.2, so .4V high is not tremendous, at all. I don't suppose whatever this is has an optional "sense" terminal? You might get ahold of the manufacturer.

Also, voltage does not equal high charge rate. You have no idea with a voltmeter, WHAT the current is doing. If the battery is quite discharged, or has a problem, like sulfated, the alternator might be working it's pants off, but it might just be floating. A voltmeter will never tell you that

"Rig" an ammeter for testing, and nowadays you can buy clamp on ones for DC. MUST be for DC. You can also listen, is it grunting/ singing hard and loud? Is the output terminal/ charge wire quite warm? Does the alternator run hot, hotter than seems normal?

Got my DC Amp meter and with fans, A/C, and ignition running the ammeter connected to the 6# bypass wire showed only 16A so think we're good there. That test does not account for the fan draw since that wire is directly connected to the alternator. Edit: the fans are pulling 24A together.