69 Road Runner charging problems
 

I have a 69 383 Road Runner and its having a bit of a charging issue. When the car is first started the ammeter is on the charge side and I have about 14.5v at the battery & alternator. After driving for about 5-10 minutes, the ammeter sits about center with a 12.3 volts at the alternator and battery. I have replaced the alternator and voltage regulator with no change in results. What could be causing the drop in voltage?

Thanks in advance!

Drew

That IS weird. One thing I'd do is rig up a temporary wire from the ignition terminal on the regulator--by the way--

are you using the old '69 and earlier "two terminal" regulator, or have you converted to the later electronic?

rig up a wire from the ignition term. on the regulator, and hook a voltmeter to it that you can see from inside. See if you have "good solid" battery supply voltage at that point, at the time that your voltage drops on your other meter

Are you SURE you have a good regulator? (Buying a new one is no guarantee!!)

Check that:

the regulator is well grounded to the body

the body is grounded (with a jumper) to the engine. Best way to do this is put (at least) no 10 from your regulator bolt right down to the engine. Also make sure that the big main ground is hooked to the ENGINE. THere should also be a smaller jumper from the battery neg. to the body, right from the battery to the body.

If that yields nothing, temporarily hook your voltmeter to the "big" battery term on the alternator and see if that point drops at the same time as your battery voltmeter.

Also, does the ammeter or voltmeter "jiggle" or jump around, or is it good and steady?

You might have a look at the dreaded "ammeter" problem, one that has seen some discussion here. What happens to these ammeters, is , that the plastic dash becomes part of the mechanics that "holds" the thing--and the electrical connections--together, so if those terminals are just a little loose, and get hot, then the plastic of the dash melts, and the connectors get even MORE loose.

Also, right after you start the car, and have your "good" 14.5 reading, what happens when you load the system heavily? That is, turn on headlights, heater, anything else that is a heavy load?

I just came in from the garage - spent the past hour cleaning the bulkhead connectors, checking for loose wires under the dash - specifically the ammeter (which were tight), I also just put a ground wire from the voltage regulator to the same bolt that the ground wire is attached to on the motor. The regulator bolts are a little stripped towards the heads, so the regulator was not completely tight - I put a washer in to get down to the good threads to ensure a good ground as well. I also check my fuses for corrosion and they were good.

I am using the 2 terminal regulator ('69 and earlier original style)

When I first start the car and have the 14.5 volts, I can turn on my lights, etc and notice a slight drop on the ammeter and the voltage stays up in the 14's...

When I use my turn signals the ammeter will jump up and down - under any charging condition.

When I was cleaning my bulkhead connectors, noticed that the connector that the big black wire plugs into was a little discolored, but i got it cleaned.

There is NO jumper from the battery - to the body....what gauge should this be?

I have not had a chance to start the car and drive it yet - it's raining. Hopefully I can do that tomorrow - after I install this negative jumper wire...

thanks for your help!

It is VERY VERY important that the regulator be grounded tight.

That just might be at least part of the problem.

The jumper from the battery to the block should be AT LEAST no. 10 or BIGGER.

I used to buy an "eye to eye" cable, rather than "battery to eye" and use them for a block-to-body jumper. That is, a cable the same size as the main battery cable.

(You learn these things when you start doing things like trunk mount battery, dual batteries, winches, and 100A alternators!!)

I forgot to mention the bulkhead connector--which is a problem especially now that these cars are old. There are at least TWO wires with very heavy current on them, one leading TO the ammeter, and one coming back FROM the ammeter. It is VERY important these be clean and tight.

On my old car, which at one time had extra radio equipment (amateur and two-way) I actually drilled out the bulkhead connector for those to main feeds and replaced them with larger no.8 feeds.

(I realize that for a "classic" you probably would not want to do so.)


(((Once, when doing some work on the '70, I forgot to hook up the frame-to-engine jumper, and I had the battery in the trunk then, so of course the battery main ground was to the frame/body. I got in and tried to crank the engine. The high current blew the retainer clip right off one of the clutch linkages up under the dash!!)))

i have a 69 roadrunner and when i bought it had a charging issue, someone had put a cheap connector near the main alternator wire and it wasn't making a good contact. soooo.. check the wires from the alternator going back to your battery for frailed, loose or broke wires. You can also take a wire and run it right to the battery for just a second and see if its charging. If it is than you know you have either a regulator problem or a wire problem.