The battery, she won't charge!

Gellpak · Aug 10, 2004

Got the new alt wired in as WORTH advised a few days ago ( http://forums.stangnet.com/showthread.php?t=489444 ), and since then have been working on various other parts of the car after testing that everything started up well (let me be the first to tell you what a difference re-grounding and re-wiring all your engine compartment electical harnesses can make... she runs so much better now).

BUT now I believe that my battery is not charging. The car is fine when running but the charge disappears quite quickly otherwise, which leads me to believe that the only charge that it's been keeping is what is jumped into it from the other car.

I've been told and seen on here that that is likely because in the process of redoing all this that I fried my voltage regulator. I've also been told that I need to make sure everything is wired correctly now, so that I don't fry the next one I put in too. So I need to figure out how to do that. Any ideas?

D.Hearne · Aug 10, 2004

Easiest way to tell if it ain't chargin, is to fire it up, then remove the pos. terminal from the battery. If the motor dies, it ain't chargin. If you still have an old mechanical regulator on the car, get a new solid state one. The old types go out at the drop of a hat, for no reason, other than they sometimes were P.O.S's

Ozsum2 · Aug 10, 2004

Have you checked to see if the battery has a dead short in it?

Ozsum2 · Aug 10, 2004

D.Hearne said:
Easiest way to tell if it ain't chargin, is to fire it up, then remove the pos. terminal from the battery. If the motor dies, it ain't chargin. If you still have an old mechanical regulator on the car, get a new solid state one. The old types go out at the drop of a hat, for no reason, other than they sometimes were P.O.S's

It should still run IF there is no pull on the electrical system. The moment there is demand it will die. Once I was driving a big hay truck and the battery fell out onto the road. I continued another 5 miles to the barn. The alt. supplied enough juice to fire the points.

WORTH · Aug 10, 2004

put a volt meter on the battery, and cross the HOT lead on the regulator with the field lead, it should go to full charge if the alt is OK. If it does then the regulator is NG or wired wrong. the hot is the large yellow wire and the field is the white wire.

D.Hearne · Aug 10, 2004

Ozsum2 said:
It should still run IF there is no pull on the electrical system. The moment there is demand it will die. Once I was driving a big hay truck and the battery fell out onto the road. I continued another 5 miles to the barn. The alt. supplied enough juice to fire the points.

That's a first for me. Must have been because of the points and a stock coil. My 68 Merc was havin charging problems the other day, we pulled the pos term. off and it immediately died. It's got a pertronix unit and flamethrower coil, nothing else in the car was on at the time.

WORTH · Aug 10, 2004

D.Hearne said:
That's a first for me. Must have been because of the points and a stock coil. My 68 Merc was havin charging problems the other day, we pulled the pos term. off and it immediately died. It's got a pertronix unit and flamethrower coil, nothing else in the car was on at the time.

it should run fine off the alternator once it's been energized.

Ozsum2 · Aug 10, 2004

D.Hearne said:
That's a first for me. Must have been because of the points and a stock coil. My 68 Merc was havin charging problems the other day, we pulled the pos term. off and it immediately died. It's got a pertronix unit and flamethrower coil, nothing else in the car was on at the time.

It was a first for me and everyone back at the barn too. It was an old truck, not sure of the vintage(pre1960) I though it had a mag but it didn't.

WORTH · Aug 10, 2004

Ozsum2 said:
It was a first for me and everyone back at the barn too. It was an old truck, not sure of the vintage(pre1960) I though it had a mag but it didn't.

WHO you callin OLD????? , once you've energized the alternator it will keep charging until you shut the key off. So it shoulod stay running without a battery.

Ozsum2 · Aug 10, 2004

WORTH said:
WHO you callin OLD????? , once you've energized the alternator it will keep charging until you shut the key off. So it shoulod stay running without a battery.

You old goat!!! Yea, turn on the lights and watch that puppy die though. So explain to me how these guys are getting the engine to die by pulling off the + batt cable. They must have the radio on or some other acc.

WORTH · Aug 10, 2004

Ozsum2 said:
You old goat!!! Yea, turn on the lights and watch that puppy die though. So explain to me how these guys are getting the engine to die by pulling off the + batt cable. They must have the radio on or some other acc.

The only way it should die is if the alternator isn't charging. I don't even think running accessories will kill it. The alternator is capable of powering everything in the car at the same time. Got Me.

D.Hearne · Aug 10, 2004

Ok, maybe someone failed to read or understand what I originally posted. I said that one way to tell if the alternator isn't charging ( a dead voltage reg. might have something to do with it too) was to start the engine, then remove a battery cable. If the engine dies, then obviously the alt. isn't charging.

WORTH · Aug 10, 2004

D.Hearne said:
Ok, maybe someone failed to read or understand what I originally posted. I said that one way to tell if the alternator isn't charging ( a dead voltage reg. might have something to do with it too) was to start the engine, then remove a battery cable. If the engine dies, then obviously the alt. isn't charging.

OOPS,,,,,,,,,,,,,,,,,,,nevermind

Ozsum2 · Aug 10, 2004

D.Hearne said:
Ok, maybe someone failed to read or understand what I originally posted. I said that one way to tell if the alternator isn't charging ( a dead voltage reg. might have something to do with it too) was to start the engine, then remove a battery cable. If the engine dies, then obviously the alt. isn't charging.

Sorry D. It takes a while for things to sink in for me.

D.Hearne · Aug 10, 2004

Ozsum2 said:
Sorry D. It takes a while for things to sink in for me.

SSS'OK It's happened to me a few times too. Brain fart Or CRS syndrome

geegee · Aug 10, 2004

The alternator has two windings...stator and field. The stator is the item that generates the electricity. Now if the alternator had a permanent magnet field (it doesn't) then the alternator would put out electricity the moment it starts to rotate. However in the Ford early alternator, a magnetic flux has to first be provided by the field winding. To get started generating, the car battery applies power to the field via the regulator. This builds the magnetic flux. As the voltage at the output terminal of the alternator rises past 14v, the regulator starts restricting current to the field to shut down the alternator. Thusly, the regulator controls the field and hence the output of the alternator.

Mechanical regulators do this regulation by pulling in a relay in the voltage regulator such the alternator actually goes on/off, on/off as the relay buzzes. When the voltage is low, the relay is supposed to be closed. When the voltage is high, the relay is supposed to be open. It cycles back and forth each time you rev the engine from idle.

Whether the alternator charges at idle is determined by the engine rpm and the ratio of the crank pulley to the alternator pulley. For a fixed size crankshaft pulley and engine rpm, a small alternator pulley will put out a higher voltage and hence higher current. The drawback of this is at high rpm the alternator gobbles horsepower. That's why a bigger pulley is used on high rpm engines (HiPo).

Now for your situation. If the alternator is spinning too slowly it will not put out a charge even if good. The speed is simply too slow. As engine speeds above idle, the alternator starts producing enough electricity to raise the voltage. It continues to rise to about 14.7 volts at 1000 rpm. Above 1000 rpm, the output becomes limited by the regulator.

The electronic voltage regulator does the same thing but does it at the speed of light rather than the speed of a vibrating reed relay.

So, in checking your alternator, simply put a voltmeter red lead on the battery + terminal and the black lead on ground or the battery (-) terminal. Run the engine at idle. Read the voltage. It should be better than 11 volts. Rev the engine to 1000 rpm. The voltage indicated on the meter should rise to 14.7 volts. At that point, raising the rpm further should not result in a voltage rise (not much rise on a mechanical regulator and no rise on an electronic regulator). If you do not get this, its time to take the alternator to Autozone and have it tested on a test stand.

Jeff

D.Hearne · Aug 10, 2004

I thought the other purpose to a larger alternator pulley, was to keep a high revving engine from over speeding the alternator and destroying the windings.

geegee · Aug 10, 2004

D.Hearne said:
I thought the other purpose to a larger alternator pulley, was to keep a high revving engine from over speeding the alternator and destroying the windings.

I won't say that that isn't a benefit. Looking at the construction of most alternators, the rotor (field) pole pieces (steel) are relatively strong and the windings are relatively light weight. I think you'd have to be over 10,000 rpm before the overspeeding would become a structural issue. There aren't too many naturally aspirated engines that get up to 10k rpm.

D.Hearne · Aug 10, 2004

geegee said:
I won't say that that isn't a benefit. Looking at the construction of most alternators, the rotor (field) pole pieces (steel) are relatively strong and the windings are relatively light weight. I think you'd have to be over 10,000 rpm before the overspeeding would become a structural issue. There aren't too many naturally aspirated engines that get up to 10k rpm.

Yes, but you have to remember that the alternator is turning a good bit faster than the crank, so at 7000 engine rpms, the alternator could very well be seeing 10K in rpms ( or higher) The 289 Hi-po was built with those rpm numbers in mind, hence the larger alternator pulley on it. I'm sure alternator construction has improved vastly in 40 years though, and over revving the alt. may not be an issue now.

Jonstantine · Aug 11, 2004

*maybe i should read your whole post before replying
but ya, you look like your on the right track

The battery, she won't charge!

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