Can I Disconnect Alternator Cable

[95strokerPSU]

Can I disconnect the charging cable off the back of the alternator so that I can get the actual voltage that the alt. is putting out and not the charge that the battery holds?

Thanks
Dave

 

[4Jenna]

Alt. issues?
I may mis-understand the question but if so just take the alt off and have autozone or someone check it...its free

 

[1TallMF]

Thing is, the charge cable on the alternator has a direct link to the positive terminal of the battery. When the car is running and you check the voltage at the battery, you are actually looking at the voltage coming from the alternator. There should not be a drop of more than a few millivolts from the alternator to the battery.

On an old dodge I had, I tried unhooking the charge cable from the alternator, and all that happened was the regulator turned off, so I was getting a few hundred volts at the alternator terminal. I don't know if Ford alternators are made the same though...

Tells us more about what symptoms you are experiencing, that can help us suggest things to check.

 

[95strokerPSU]

Already took it to Autozone and they say it's fine, but I'm still having problems so I don't trust their test completely.

Thing is, the charge cable on the alternator has a direct link to the positive terminal of the battery. When the car is running and you check the voltage at the battery, you are actually looking at the voltage coming from the alternator.

Exactly, but it works inversely as well. So if my alt isn't putting out anything then I'm going to see the battery voltage if I probe the charge cable at the alt. because it is a direct link. So can I disconnect that cable, hence breaking the link, to find out what the alt is actually putting out?

 

[badstang123]

Have you had the battery load tested? This is always the first test I do when I have an electrical problem. A battery going out can create a lot of problems with voltage. Make sure you have the battery charged first though so it get the load tester gets a good reading. If that checks out, I would have the alt restested, but at an actual alternator shop. They can give you a better analysis of what's going on with it.

I don't see why you couldn't disconnect the cable, but I think you would be better off having a good shop test it. Then they could tell you if you have a bad diode, how many amps it puts out, how much voltage. An alt shop does it every day so they could offer a lot more help. It would tell you a lot more than you just getting a voltage reading.

- Justin

 

[mo_dingo]

Already took it to Autozone and they say it's fine, but I'm still having problems so I don't trust their test completely.



Exactly, but it works inversely as well. So if my alt isn't putting out anything then I'm going to see the battery voltage if I probe the charge cable at the alt. because it is a direct link. So can I disconnect that cable, hence breaking the link, to find out what the alt is actually putting out?

Easy. With the car off, check the battery voltage. Then with the car on, check it again at the battery. It should be 1V higher or so, depending on whether or not the battery is charged. You should see at least 12.5 or so w/ the car off, then with the car on, 14.4V for a few minutes, which should trickle down to 13.5 or so.

And if you want to see how many amps the alt is charging at, borrow a DC amp clamp and put it on the alt charge wire.
Scott

 

[1TallMF]

If you disconnect the charge wire, whatever you do, make ABSOLUTELY sure the wire touches NOTHING. Speeking from experience here. I had this happen and ended up completely melting the ring terminal on the wire. Not to mention getting a good ZAP from it.

 

[95strokerPSU]

Easy. With the car off, check the battery voltage. Then with the car on, check it again at the battery. It should be 1V higher or so, depending on whether or not the battery is charged. You should see at least 12.5 or so w/ the car off, then with the car on, 14.4V for a few minutes, which should trickle down to 13.5 or so.

And if you want to see how many amps the alt is charging at, borrow a DC amp clamp and put it on the alt charge wire.
Scott

I've done that and there's no increase. So I think I found a good shop (aka not Autozone) that I'm just gonna take my alt to. It'll be on the way for me this Saturday as I have to go over to dirty jersey and pick up my MM roll bar that I just got off eBay.

Thanks guys
Dave