Alternator is overcharging....

Jim Oaks · Sep 27, 2011

When I replaced the bad V-8 in the Bronco II that I bought with the 302 out of my old Ranger, I removed the amp guage from the dash and just spiced the wires together.

When I finally got this thing running and was checking the guages, I noticed it was cranking out like 16-17 volts!

I replaced the voltage regulator with another one I had and it was fine for a minute or two, and then krept back up to 16-17 volts.

Is there some kind of resistance in the Amp guage that it won't let me just remove it and connect the wires together???

In case your wondering, I removed the Gen I dash and put in a Gen II dash that had a voltage guage, not amp guage.

Thanks.

4x4junkie · Sep 27, 2011

Is this a standard Ford integral-regulator alternator?

I'm kindof just guessing here, but it sounds to me like there's an open circuit in the voltage sense lead to the regulator. If this input terminal has no connection on it, the alt will then run fully-unregulated, putting out max voltage (your battery being the only thing limiting it from going higher than 16-17 volts).

Check and see if full battery voltage is present at the "A" terminal on the back of the regulator with the key on (engine not running). IIRC, that is where the regulator senses the voltage.

Also, make sure nothing is grounding against the "F" terminal (it should read the same voltage as the "A terminal with the key OFF).

Earl43P · Sep 27, 2011

See that 510 ohm resistor in parallel with the Ammeter?
You need that, can't just splice the wires together.

http://www.therangerstation.com/tech_library/EDiagrams/files/Diagram_charging_1991_1.JPG

Jim Oaks · Sep 27, 2011

Hmmm......

When I got rid of the dash in the old Ranger (well after the V-8 swap) and created a custom one, the alternator stopped charging the battery. I traced it back and found that when I removed the battery light (idiot light) it stopped charging. I forget how this system works, but the connection was basically needed to 'excite' the charging system to start charging.

I figured I couldn't just break the connection at the Amp guage because current flows through it.

This is the diagram for the charging sstem I have:

Will · Sep 27, 2011

The '91 diagram doesn't apply here.

That ammeter can be disconnected without attaching the ends back. For safety reasons, full current doesn't go through them. There isn't a resistor in that ammeter shunt.

If the regulator wasn't working, all the lightbulbs would blow out when you revved the engine.

One wire is the sensing wire. It is downstream in the electrical system somewhere. Probably, it runs to the main power feed. It is the feedback wire and the regulator is going to try to keep it at 14.7v. If there is higher than normal resistance in that wire, the rest of the system will go above 14.7 to make that wire read 14.7.

I'm not up to speed on that external regulator charging system right now, but I would check out that yellow wire with the white stripe on the diagram. If that one has unusually high resistance, that could do it as I think it's the sensing wire.

Jim Oaks · Sep 27, 2011

Will said:
If the regulator wasn't working, all the lightbulbs would blow out when you revved the engine.

That's no lie. Once we were coming back from Wellsville in the rain and at night. My voltage regulator went out and blew out my lights. I had a truck in front of me and a truck behind me so I didn't get hit, and was holding a flashlight out the window while I was driving.

Damn good time.

Capt Jay · Sep 27, 2011

First, don't trust the gauge. Start it and put a meter on the batt and check what it's actually reading. If it's really 17 then change the alternator. It's miss-reading need/draw, and over charging.

Jim Oaks · Sep 27, 2011

I did double check it with a volt meter. Overcharging.

When I replaced it with another one I had it was working fine, and then the needle started going up and was overcharging again. I'm hoping I just have a wrong connection.

Capt Jay · Sep 27, 2011

The reason it worked initially is the battery was working as a shock absorber. I think your voltage regulator is bad. I know you changed it, but remember a lot of parts are bad on the shelf. The charging system is a very simple system. The regulator senses need and energizes the alternator. If there is a short it doesn't effect the charging system. It will pour out as much energy as requested, and blow any fuses it over charges.

Capt Jay · Sep 28, 2011

You might also want to check your battery. If it has a weak or dead cell, you'll sense low volts/high need.

kimcrwbr1 · Sep 28, 2011

If you notice there is a shunt or a solid wire that the amp guage is inline parallel to the shunt. The amp guage just tells you what direction voltage is flowing either into the battery or out of it. The volt meter just measures voltage at the battery. Pull all your grounds apart and sand them metal to metal you may have burnt up both regulators it dont take long to burn up all three. A bad battery can destroy the alt/reg and visa versa. Your getting voltage to the battery from the alternator check the wires to the regulator are correct and good depending on the system you are using. My 83 has key on hot to the regulator and the stator wire is terminated (not used) the field wire tells the alternator what to do. If your not getting battery voltage to the regulator B terminal the shunt was in the amp guage and you will need to connect a jumper where the amp guage was. You might be alright if you didnt run it very long without the battery wire to the regulator it is telling the alternator to run wild. GL

kimcrwbr1 · Sep 28, 2011

Is your regulator grounded properly?

kimcrwbr1 · Sep 28, 2011

Actually you cant have too many grounds batt to chassis, engine to chassis, batt to engine, batt to alternator, engine to regulator anything that draws alot of power to batt. Good marine grade batt terminals make connecting grounds alot easier.

4x4junkie · Sep 28, 2011

Jim Oaks said:
Hmmm......

When I got rid of the dash in the old Ranger (well after the V-8 swap) and created a custom one, the alternator stopped charging the battery. I traced it back and found that when I removed the battery light (idiot light) it stopped charging. I forget how this system works, but the connection was basically needed to 'excite' the charging system to start charging.

I figured I couldn't just break the connection at the Amp guage because current flows through it.

This is the diagram for the charging sstem I have:

http://www.therangerstation.com/tech_library/EDiagrams/files/diagram_charging_1983to1985_1.JPG

So it's an external regulator alt...

I'm wondering if the ammeter shunt needs to stay inline with the circuit maybe and the wires that originally went to the cluster (R/O and Y/LG) just left open? It would appear that the "Y/W D" wire is the sense lead, so I'd certainly check that similar to how I mentioned in my above post, make sure the voltage at the regulator's A terminal is not more than the tiniest fraction of a volt less than at the battery itself.

Jim Oaks · Sep 29, 2011

I haven't messed with it yet. I took the carb bowls off and did some cleaning. Found crap in the accelerator pump, and that the pump valve (right under the nozzle at the top of the carb) was stuck close.

I bought a new regulator, but I'd really like to figure out the charging issue before hooking up a new regulator and damaging it.

Alternator is overcharging....

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