Electrical Problem in 1965 Fastback

PJ Smalls · 06-12-2006

Need some help. Some problem with battery being zapped of it's juice. New battery, alternator has been checked and is in good working order, and swapped the voltage regulator out. Car starts right up with jumper cables, and runs fine for a while then starts to cut out when i get on the gas and eventually dies when i come to a stop then won't restart until i get a jump. Any ideas on what i should do? Any help would be greatly appreciated.

Blade10 · 06-12-2006

You need to measure the voltage on the battery with the engine off - you should see around 12. Start the vehicle and measure the voltage again - and with the engine running you should see 13-14 volts. If you dont have 13-14 volts try revving the engine slighty. If there is still no increase then you have a charging system problem.

Blade

PJ Smalls · 06-12-2006

Thank you I will give it a try.

Tominator · 06-12-2006

Quote:

you should see around 12.

12.6 at full charge or you have a battery problem.

PJ Smalls · 06-13-2006

So far so good have run it a couple of times and checked the voltage and got 12.8 each time. I've noticed that when i have the stereo on it runs down the battery, I'm wondering if that was causing me problems, is that a possibility?

stang36 · 06-15-2006

What was the voltage with the engine off? Check the voltage with the engine OFF, write it down for future reference.
12.8 isn't very good for a charging voltage. Like blade said you should have 13-14 volts. Unless you have a serious stereo system (high watt) you shouldn't see much of a drop if any from JUST a stereo being turned on.
I would think with the engine at 2k rpms you should be able to run the headlights and blower motor and maintain .5 volts higher then the base voltage reading while the engine was off.

Sounds like you have a charging problem. How was the voltage regulator checked??
Run the engine around 2k rpms with your voltmeter hooked up on the battery terminals. All accessories must be OFF. You should see 13.5-14.5. If its steady but lower then this, the regulator my be faulty. Same if its higher, but this is not going to apply to you.

Did you full field the alternator? That is make the alternator produce maximum output. To do this, direct battery voltage is going to be used to excite the rotor field of the alternator.

Do this test at idle rpms, or you may ruin the alternator!!
Take a jumper wire and connect it across the BAT and FLD terminal on the back of the alternator. This should jump the voltage to max. If its still around 12.8v like before then the alternator is probably bad, but if it jumps up to around 14v then the regulator is probably bad.
You can also unplug the regulator and take the jumper wire from the A terminal to the F terminal (usually the second and forth wire) on the plug and do the same test.

Also with the engine off you should see battery voltage at the A terminal.
Make sure you have checked all the basics. Like the condition of the belt, belt tension, battery cables for tightness and making sure all connections are clean.

Blade10 · 06-15-2006

Quote:

Originally Posted by Tominator

12.6 at full charge or you have a battery problem.

I agree, (and here it comes) BUT - I didnt give tenths of a volt because most people dont have meters that are accurate enough. YES they *display* the "12.623" volts but since the mete is not calibrated the ".623" is probably meaningless.

If its close, I call good enough. Like I said - "around 12"

Blade

PJ Smalls · 06-15-2006

I have taken a couple of drives to see what kind of voltage I get when I turn it off. Each time I shut the engine off and tested the voltage it went from 12.6 to 12.4, then from there it went to 12.1 after the next run. The battery charger that i'm using has an alternator tester on it, and it comes back with a fault when I test it, but i don't know how reliable it is since it's a cheap battery charger. I also had my wife rev the engine with the tester on to see if it would read about 14 volts, but it just stayed around 12. I'll try the things you suggested and see what I get. Thanks for the info guys.

dlinebar · 06-15-2006

If its reading 12 volts with the engine running it ain't charging....replace the voltage reguiator and alternator at the same time....about $80 at Advanced auto parts...

stang36 · 06-15-2006

Jumper the "A" and "F" terminals together on the plug for the regulator, start the engine and let it idle. Voltage should be around 14v. If not then the alternator is probably bad. Take it off and take it to the parts store and have them check it out to double check it. You might be being one anyway, so it won't be a wasted trip

PJ Smalls · 06-16-2006

Took it for a longer drive tonight, stopped at the gas station to fill it up, hopped back in tried to start it and got nothing but the clicking of the starter solenoid. I used a jump starter and it fired right up. Got it home shut it off, same thing couldn't get it started, just clicking. Tested the battery was reading 11.9. I noticed that the plug that goes into the voltage regulator is fairly loose. I'll try to correct that and test it this weekend. Also should I replace the starter solenoid, along with having the alternator re-tested and replaced if need be?

stang36 · 06-16-2006

The starter solenoid should be fine. Its just clicking because there isn't enough juice to turn the starter over.
While your messing with the plug shove a jumper wire into the A and F terminals and start the car and see if its around 14v.
The terminals are usually marked, either on the plug or the regulator. The one that is marked A should show battery voltage on that wire. If its not the you may have a wiring problem.

PJ Smalls · 06-16-2006

I'll try that and see what I get. Thank you.