new alternator, new battery...still no charge

[cheap5.0]

When i bought the car the seller told me he put a new alternator on it about 6 months prior to me purchasing it. When i picked it up i put a new battery in it. Now it still won't hold a charge, and i tred pulling every fuse and checkin the ground on the battery for arc'ing. Maybe there is another fuse box i don't know about, but i have a chiltons manual and i have read damn near eveything i could find about troubleshooting this problem and i still can't fix it! Oh yeah, when i do jump the battery to start it, it does not need to charge at all. As soon as i put the jumpers on there it fires right up. Without them there is nothing, not even a click.

[67coupe]

Need a little more info.

1. If you jump it off and drive the car does it work ok?

2. If you switch it off after running awhile will it restart right then?

3. If answer to 1 and 2 is yes then how long does it sit before it's dead again?

[351wStang]

Sounds to me like you have a slow electrical drain.

[thunderbird muscle]

Check to see if something stays on when the car is cut off. Do you have an aftermarket sound system in it?

[cheap5.0]

67 coupe, the answear to one is yes, the answear to two is yes and no. it depends on how long i let it charge, if i jump it real quick and disconect the jumpers and drive off, it will not start again. But if it sits for about an hour with the trickle charger on it it will start about a dozen times. And three is about 12-18 hours depending on charge given to it. Thunderbird muscle, i wish there was something inside of the car, but really all it has is a aftermarket cassete deck. Everything else is stock. I just thought of something though, it is hot wired. Could there be something loose there that would kill it?

[Wolf]

To check for drain, with the engine off, disconnect the negative battery terminal and place a 12v test light between the terminal and the battery cable. If you get a light, there's a drain. No light=no drain.

I'd bet anything it's just a bad alternator. Pull it off, take it to Kragen/Checker/Shucks and have them test it. I had a 1 year old alt on my SVO, had a similar problem (except it would take about 3-5 days before the battery would be drained.) Turns out my "new" alternator was only putting out 9amps instead of 14, so the battery wasn't charging. New alt w/ a lifetime warranty fixed the problem.

[cheap5.0]

I had the alt checked at an autozone near me and it is good, but the guy testing it sugested that i should check the power cable going from the alt to the battery. Does anyone think the cable could be so far shot that it won't carry a charge?

[drummerguy]

I had an '89 that did the same thing. I replaced the fuse link in the selinoid(sic), put on new battery cables and made sure there was a good ground to the block. After that, it ran fine. Does your car "lope" at idle? Mine did that as well and it was also a contributing factor to my charge problems. I fixed that by replacing the fuel relay switch located under the drivers seat. Then I traded the car for a '96!! Hope that might help you out a tad!

[cheap5.0]

drummerguy, by "lope" do you mean surge a 100 RPMS then drop a 100 below where it was then shoot back up (repeating this often), then yes it does "lope". Thanks for the info about the fused link.

[Larry in CA]

Take a digital meter and set it to the 20 volt DC setting.

Measure the voltage from positive battery post to the negative battery post. Now, take a reading from the positive battery post to the negative battery cable and then from the negative battery post to the positive battery post. All three readings should be the same without any variances. If there is a difference in any of the readings, you have a bad connection between the cable and post and need to clean the posts and cables.

With the engine running in Park, take a reading from battery post to battery post. The reading should be somewhere above 14 volts. If you have less than 14 volts, your alternator is possibly the culprit.

My son ran the battery down on my sable and I recharged the battery and re-installed it in the car. A couple of days later, he drove over to a friends house and when he started home the car would not start. I found that although the cable appeared to be on correctly and tight, there was just enough corrosion on the post to cable connection to prevent the alternator from recharging the battery. Using a wire brush has solved this problem.

[tooldesk]

I am a former automotive technician now turned webhead. I find it to be a much cleaner profession with a few less headaches. I hope I may be of help … here we go!
First of all I have to assume your 67 coupe is stock with now aftermarket ignition etc.
The electrical load of a 67 stang is really not much compared to the newer vehicles with electric fuel pumps and computers and high energy ignition systems that require more load.
I would check the alternator for a bad diode which could create a drain on the system while the vehicle is off and not producing any charge. The alternator may still charge enough with a bad diode to keep the car running and even trick the charge light (if equipped so) to go off with the vehicle running.
If the vehicle runs fine after jumping it and produces a charge in the battery, I also assume that the exciter circuit is working properly. This is the switched voltage to the alternator which is necessary to get the alternator to start charging. This is a widely misdiagnosed problem which causes a lot of money wasted for replacement alternators. An alternator cannot charge if it has no exciter current at startup.
Another possibility is your regulator. The 67 mustang should have an external voltage regulator that could malfunction and “hang up” or “stick” causing a discharge when the vehicle isn’t running. It is a relatively inexpensive item, although it is good to diagnose properly rather than replacing parts which can get expensive in the long run.
It is also entirely you have gotten a bad "new" battery. This is not as uncommon as one would think. I bought a new Everstart battery for my STS only to have the same condition you are describing. Some times it would be dead overnight, and sometimes it would take a couple of days. I brought the "new" battery in to have it tested, and got the answer ... oh its "good".
Needless to say, I replaced it again and never experienced the problem again.

Wolf posted: Turns out my "new" alternator was only putting out 9 amps instead of 14, so the battery wasn't charging. New alt w/ a lifetime warranty fixed the problem.
What he should have been told that his alternator was putting out 9 volts instead of 14 volts.
The average amperage for an alternator of that vintage auto without A/C, power windows, power seats etc. would be in the area of 38 to 70 amps depending on the particular vehicle.
Most posts in this forum are correct for the most part, but it sounds to me like you may have just gotten a bad new battery.
One easy test you could do is to take off your battery cables when you leave your car sit and see if the battery loses its charge. If it does, than I would replace your "new" battery. Hope you find your problem and happy motoring.

Gordy SEO www.tooldesk.com