Putting out too much volts at idle!!! 16-17 volts!!

[jenkins71]

Hi guys! My 71 Charger is, well, overcharging. I first started noticing something was up when my Kenwood radio starting cutting off. Well, I poked around with the multimeter and found that the battery feed line was showing 16.5 volts!!! Whoa!!!

I then poked under the hood and found the same reading directly off the battery posts. Ok, so, new voltage regulator, right? Tried that first. Same voltage. It seems to start off ok, like at 14volts, then climb, at idle mind you, to 16-17 volts.

Tried wiggling all connections. Nothing. The engine wiring harness is a new reproduction unit, very nice quality. Tried unplugging the radio. Nada.

Any ideas? I'm at the end of my rope over here!

Thanks!!

 

[bigmanjbmopar]

Have your battery tested with a load, cells may be messed up.

 

[jenkins71]

Have your battery tested with a load, cells may be messed up.

How do I do that? Thanks

 

[Shorthorse]

A great tool to have around. These can be purchased at Harbor Freight and Sears for 20-25 dollars.
However, your problem may be deeper than that. 16V is way more than a regulated alternator should put out. If you remove the alternator, most auto parts stores will test them for free. If it checks out OK you probably have some sort of giant drain. Because you mentioned a new engine harness, that's the first place to look.

 

[mmissile]

http://www.forbbodiesonly.com/moparforum/showthread.php?97783-Over-charge-in-the-road-runner

440 roadrunner, was very informative. I'm sure your problem will be inside or grounds. Mine was a variety of issues.

 

[440roadrunner]

Hi guys! My 71 Charger is, well, overcharging. I first started noticing something was up when my Kenwood radio starting cutting off. Well, I poked around with the multimeter and found that the battery feed line was showing 16.5 volts!!! Whoa!!!

I then poked under the hood and found the same reading directly off the battery posts. Ok, so, new voltage regulator, right? Tried that first. Same voltage. It seems to start off ok, like at 14volts, then climb, at idle mind you, to 16-17 volts.

Tried wiggling all connections. Nothing. The engine wiring harness is a new reproduction unit, very nice quality. Tried unplugging the radio. Nada.

Any ideas? I'm at the end of my rope over here!

Thanks!!

First determine if the wiring and VR has control so to speak. To do that

1....Pull the green field wire off at the alternator. Briefly run engine, run RPM up and see if it charges, see if voltage goes up. voltage should stay at battery voltage

2....Hook above back up, remove connector at VR. Repeat test, again, "should not charge."

3....Make ABSOLUTELY certain VR is grounded. Scrape around bolt holes and rear of VR flange, mount with star lock washers. Some guys add a No10 ground wire from one of the bolts to the block

4...Next check for voltage drop, both in the wiring harness and ground side To do that..........

4A....With everything hooked up normal, backprobe the blue wire field connection on the alternator. Leave all wiring connected normal. With one meter probe on the blue wire, stab the other probe into the battery POSitive post. Do this with engine stopped, and key "in run." You are hoping for a very low reading, no more than .3V (3/10 of one volt) OR LESS.

If this reading is high, say 1/2 volt or more, this indicates a poor connection. The circuit "path" in a factory harness is battery......start relay......fuse link......through the bulkhead..........through the ammeter........to the ignition switch connector..........through the switch..........out the switch connector (on blue "ign 1") ..........back through the bulkhead on the blue...........and into the engine bay and ignition, VR, alternator field, etc

A high reading indicates a BAD connection in one of the above. Most likely is bulkhead connector terminals, the ignition switch connector, or right in the switch itself

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++

4B...With everything connected normal, run engine to simulate "low to medium cruise" RPM. Do this test first with all loads off, and again with lights, heater, etc turned on.



Stab one meter probe into the battery NEG post. Stab the other into the VR mounting flange. As above you are looking for a low reading, the lower the better, and zero is perfect. If not, this means the VR is not "actually" grounded to the battery NET



If all the above checks out OK, it's a tossup..........either remove the battery and sub a known good one, or have the battery tested

Or.......replace the VR

 

[bigmanjbmopar]

How do I do that? Thanks

You can take it to any auto parts store most all of them have battery testers, it will put a load on the battery and measure the charge its holding and voltage it is outputting, should determine the health of the battery. An over charge could be caused by a bad battery making the alternator work harder to charge it.

 

[440roadrunner]

. An over charge could be caused by a bad battery making the alternator work harder to charge it.

This does happens but frankly, not very often. Often a bad battery will "act" like overcharge by bubbling over, but the charge voltage will still be a correct 13.8 or so. In this case his voltage is too high, usually a different "horse"

 

[bigmanjbmopar]

It's an easy check and one he can cross off the list of possibilities simply by taking it in to get tested. The only other two things it could be is the alternator or the regulator, he states he has replaced the regulator which leaves the alternator, or even the reproduction harness that is installed could have a crossed wire. either way checking the simple things first for a novice is the best advice. If you expect him to read your novel which is fine but not every one of these questions for help need your standard book you seem to post on every one.

 

[jenkins71]

Hey guys. Thanks so much for your valuable information! I took the alternator off and had it checked at the local parts store. It failed the test, so I bought a new one. Which did the trick! Charging at around 14.7 volts.
Thanks guys!
Sam

 

[bigmanjbmopar]

Sweet glad you got it fixed, most times it's the simple things to check first.

 

[jenkins71]

Yeah, seems simple right? Well not for me. I went to the parts store and all they came up with was an alt with a single spade for the field, where mine had 2 (blue and green). So I added a spade to the screw on one of the brushes, thinking that would adapt it fine.... Well it didn't, it melted my blue wire once I turned the key on. Hahaha. DAMN. I replaced the wire and re-wrapped the harness with non-adhesive tape, and you can even tell now, but DAMN did that suck. So I returned that alternator and they couldn't come up with a 2-field alt for a 71 Charger! So I said "let's try a 1978 Charger," and sure enough the pictures looked just like my alternator with the big square boxy opening on the back.
Alls well that ends well... But it took a whole day with driving out the the HUB and back twice, and changing two alts, and repairing my harness .... Lesson learned!

 

[440roadrunner]

Yeah, seems simple right? Well not for me.

MAN I wish you'd posted back before you went through all that. God Dammit I sure get tired of incompetent parts people. This is the difference between "now" and "my previous life." Back then we actually READ catalogues, and LOOKED in parts interchanges, and if nothing else we pawed physically through parts boxes.

Where I grew up, there was all kinds of "logging jammers" Willys Jeep engine swaps / winter plows you name it. Hell there was even one "Ag cat" crop duster who used a Mopar alternator on his airplane!!

 

[Cranky]

I've been through this same wringer a few times with these guys that look at a computer and try and say it'll work. Hell, most of them never heard of a Plymouth let alone a Belvedere lol

 

[jenkins71]

Yep it sucks.

 

[Shorthorse]

MAN I wish you'd posted back before you went through all that. God Dammit I sure get tired of incompetent parts people. This is the difference between "now" and "my previous life." Back then we actually READ catalogues, and LOOKED in parts interchanges, and if nothing else we pawed physically through parts boxes.

Where I grew up, there was all kinds of "logging jammers" Willys Jeep engine swaps / winter plows you name it. Hell there was even one "Ag cat" crop duster who used a Mopar alternator on his airplane!!

I count myself lucky. We've got a NAPA store close to the shop with a couple of real parts guys. They do all the things you're talking about 440roadrunner. Great place to go.

 

[jenkins71]

Yeah, NAPA's are generally better it seems.

 

[jenkins71]

OKAY GUYS



It's like 6 weeks later..... New alternator, new VR. BACK TO 17 VOLTS!!!!!


Arggghhhhh... I'm at my wits end with this thing! Guess it must be in the wiring...

 

[bigmanjbmopar]

Here check these out and study them,


Make sure you have the blue and green wire on the alternator correctly connected to the right fld "field terminal" or for shits and giggles use these guides to help make sure you have it all hooked up right. It's important to note the blue is positive + and the green is negative -

Also do you have pics of your engine setup? Have you changed the pulleys at all? Something is burning up your alternators. Too much tension on the belt perhaps? amp meter hooked up in the dash?


http://www.mymopar.com/downloads/1971/71CoronetChargerA.JPG


http://www.mymopar.com/downloads/Dual_Field_Alternator_Wiring.jpg


http://www.mymopar.com/index.php?pid=80

http://www.mymopar.com/index.php?pid=78

 

[jenkins71]

So I found the body ground wire was broken.... And I also ran a 10ga wore from the Alt output to the battery post on starter relay. All problems solved....
Shrug!!