Ammeter Shows Discharge - Alternator is Good. Now What?
 

67 Catalina. When I start the engine, the ammeter shows normal, just slightly above the mid-line. Then the needle moves slowly to total discharge after about 20 seconds. Stays at total discharge until I turn the car off again.

Checked the battery voltage motor off - 13.2v. Start car, voltage goes to 14.2v which tells me that the alternator IS putting out the voltage it should.

Got any clues? :confused:

Does it have the stock 10DN (external regulator) alternator or something later ? If stock it may be a stuck regulator. Try hitting with screwdriver butt.

Yes - the ol black box on the firewall. Tried the screwdriver trick but no change

check the meter connections.

If it's running at 14.2 constantly, the charging system is working.

i also would be suspicious of the ammeter/connection.

george

X2. Trust the voltage.

There is nothing wrong with your charging system. It sounds like your ammeter died. Install a voltmeter and don't worry about the ammeter. Ammeters are nothing but trouble and yours doesn't read full amperage anyway. It has a shunt. I converted mine to a voltmeter myself (not hard) but there are companies that will do it for you.

Amp hand going full tilt discharge tells me more is going on here than wires switched on the meter or alt (+) and B (+) being switched under the hood.

Full tilt from a missing shunt will burn the meter up.

Meter wired to show full alternator output will burn the meter up.

Wired factory the ammeter shows electron flow going to or coming from the battery and nothing else. That's battery charge or discharge and not how many amps the alternator puts out.

Untill this gets straightened out... I would add a jumper wire from alt (+) to B (+) so you don't run too many amps through the meter and it's wires. At amp hand full tilt your passing more current through the meter and its wires than it was suppose to ever see.

Add the jumper to prevent smoke and flames
Clay

PS nothing wrong with factory ammeters when wired correctly and doing what its suppose to do. You can add a volt meter if you like with no change or affect on ammeter function.

Update: So yesterday the car left me stranded - battery was too low to start. I got it jumped and back home. After I got it started I noticed that the ammeter - which usually shows full discharge - was now reading slight charge.

Got home and left it running to read voltage - it showed 13.2 volts at the battery terminals. I put it on the charger overnight and figured my next step should be to change out the regulator? This one has but 2 wires going into it... I assume that's normal. (It's always fun trying to figure out what the PO has done....)

To recap a bit, when I first start the car the ammeter shows charging, then slowly goes to full discharge within about 5 minutes.

Ideas?

Start the engine. Remove one of the battery cables. If it dies, you are not charging....

"Bill"!

If that's the only regulator in the system, rewire the alternator . No way that reg with only 2 wires is going to work correctly. The wiring needs to be checked and corrected. The PO was doing something creative.

George

Check the number on your regulator. The 1119511 1119517 D633 were wired that way. If you have changed the regulator it is probably the wrong one. If it is an after market reg take the reg cover cap off. The correct reg will have only one coil as opposed to the more common two coil regs. The correct reg may be hard to find. It is possible to use an old chrysler mechanical 2 wire reg until you find a correct one. Usually the 1119511 will have only 3 terminals, but I have seen some aftermarket replacement units with 4 terminals like the more common 119515, so removing the cover will tell the truth as to what reg it is.

If you need one check ebay . They are still selling there. Not so sure you will find one at a parts store, but maybe.

I'm sticking with my first thought. And what would happen running without a shunt.

Wires are switched on the meter OR under the hood, making the meter read backwards. No shunt made the needle go full tilt. Now the meter is fried and alt charge doesn't have a pathway to the battery to keep it charged.

The new running battery volts is the same as post #1 engine off battery volts.

(1) Need a running volt test from alternator B+ post.

(2) Engine off, Battery + cable off... Take an ohm reading from alt + post to the loose battery + cable end. I suspect you'll find it open or really high resistance.

That's my thoughts on this and I could be wrong. But... It makes sense to me
Clay

That makes good sense to me Clay. My first thought was burnt connections at the amp meter. Volt test at alt +post when running would possibly reveal a direction to pursue. I still think he needs to double check what regulator is on the car. A normal 4 wire reg won't work with the wiring shown.

Mark,
He was getting charge to the battery in the first post. Just had an exaggereated discharge reading on the ammeter.

Zooming in on his regulator pic. The voltage sensing wire doesn't "look" to good next to the connector. Like it's close to breaking. Might be insulation only but I would have to check it.

https://forums.maxperformanceinc.com...1&d=1634570491

Clay

Delco 2 wire reg 1119511
 

Delco 2 wire reg. George, check this out. Not common, but used on some big pontiacs for a few years.

:)Clay, a simple test might be to reach a hand up to the ammeter connections when the car is running. If the fingers come back out burnt and blistered he will have found the problem area.

Markpj3 , How many wires are going to the alternator plug?

Tried this, engine stays running no problem.