Alternator/Charging Issues

splenderleith · #1 (**permalink**) 08-08-2021, 07:33 AM

It is a superfomance cobra, purchased in 1996 with the 460 crate motor. I replaced the external voltage regulator yesterday, with no apparent change. The battery is brand new, but there was no battery in it when I received it. I purchased one that fit in the space and hooked up the + and - thick wires to the battery. The battery starts the car well and runs all of the accessories, but it completely drains within about an hour of driving.

I am not sure if there are any smaller wires that need to be hooked up to the battery terminals. I may pull it back out to see if I can see anything. The guy at the auto parts store said that if I probe the positive post on the alternator and ground the other probe, I should get 14.4 volts, but I get almost nothing. I am wondering if the wire positive wire may be grounding out somewhere, due to a worn insulation issue. I am not very strong electrically, so it is quite possible it is something very simple.

cycleguy55 · #2 (**permalink**) 08-08-2021, 12:52 PM

Quote:

Originally Posted by splenderleith

It is a superfomance cobra, purchased in 1996 with the 460 crate motor. I replaced the external voltage regulator yesterday, with no apparent change. The battery is brand new, but there was no battery in it when I received it. I purchased one that fit in the space and hooked up the + and - thick wires to the battery. The battery starts the car well and runs all of the accessories, but it completely drains within about an hour of driving.

I am not sure if there are any smaller wires that need to be hooked up to the battery terminals. I may pull it back out to see if I can see anything. The guy at the auto parts store said that if I probe the positive post on the alternator and ground the other probe, I should get 14.4 volts, but I get almost nothing. I am wondering if the wire positive wire may be grounding out somewhere, due to a worn insulation issue. I am not very strong electrically, so it is quite possible it is something very simple.

Ford-type alternator or some other type (e.g. GM 1-wire)? What wiring connections do you currently have?

I'd be inclined to not only double-check the grounds, but install a ground wire from the alternator to the chassis / frame. You can never have too many grounds (within reason).

splenderleith · #3 (**permalink**) 08-08-2021, 03:49 PM

Just to try to rule out more items, I jumped the voltage regulator and I was able to get voltage out of the alternator. With that, I put the old voltage regulator back in. I was hopeful that whatever was wrong was fixed, but no such luck. I unattached the red wire and ran one from the alternator to the solenoid. It seems like the alternator is now generating more current than the battery. My thoughts, at this point, are that I may be able to run some new wires and get some positive results. The light above the ignition goes off when it is running, but the amp meter still stays negative. The ignition light going off is the most progress I have made in days. Hopefully this works enough for me to rule out some things.

splenderleith · #4 (**permalink**) 08-08-2021, 03:51 PM

The alternator has 4 wires. One red, one white, one black and a brown for ground. It appears that there is a 5th post that is not used.

Blas · #5 (**permalink**) 08-09-2021, 05:58 AM

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Blas

1795 · #6 (**permalink**) 08-09-2021, 06:39 AM

Not sure if your alternator is similar to the one that I had in my MGB race car. I was having a similar problem as I completed that build, in that the alternator (which tested as being good) was not charging the battery. Turned out that I had to wire in an idiot light that would turn on and tell the alternator to charge the battery. Your alternator may require a signal as well.

jhv48 · #7 (**permalink**) 08-11-2021, 07:42 AM

Quote:

Originally Posted by 1795

Not sure if your alternator is similar to the one that I had in my MGB race car. I was having a similar problem as I completed that build, in that the alternator (which tested as being good) was not charging the battery. Turned out that I had to wire in an idiot light that would turn on and tell the alternator to charge the battery. Your alternator may require a signal as well.

I think he may have hit on the answer. Does the red light on your dash glow? With a one wire alternator, the light is left out. If you have an external regulator, the light must be connected for the circuit to complete.