Alternator too big?

69 bee 383 auto.ac.only had car about 3 mos,had a new diehard batt from po.it started to spin slow at start.would not hold a charge replaced it.also has alt checked a few days later by 2 stores,both says replace the alt.so I put a 65 a durlaat with 2 fld.my orig had one fld.so from advice here I grounded the ,extra fld terminal and also ran a line
from batt stud on new alt to start relay post.put on a new solid state vr as well.driven it yet,but using a voltmeter I wee 12.7 at idle and around 16 plus at higher rpm.should I just go back to basic atuff.afraif I'm gonna fry aomething(old alt was 60 a).

Probably nothing wrong with the parts, rather the wiring

Several possibilities

Poor ground at the regulator can cause over voltage

Voltage drop in the ignition harness can cause over voltage.

Generally, problems in the bulkhead connector are getting worse as these cars get older

Start by reading this article which points out some of the pitfalls and problems of the bulkhead connector:

http://www.madelectrical.com/electricaltech/amp-gauges.shtml

Then, check a few things out.

FIRST, get your multimeter, set it for low DC volts, and turn the key to "run" with engine off. Stick one probe on the battery post, or the start relay battery stud. Stick the other probe onto the regulator IGN terminal. If you are running the original regulator, this is the "push on" terminal not the screw terminal.

You are hoping, here, for a very low reading, the LOWER the BETTER. Anything over .3V (three tenths of one volt) means you have a voltage drop problem.

The circuit path you are checking is battery -- fuse link -- through the bulkhhead-- through the ammeter -- to the in harness splice -- to the ignition switch connector -- through the switch -- back out the switch through the switch connector -- and back out the bulkhead connector on the DARK BLUE "ignition run" wire, which supplies the dash cluster, warning lights (oil, brake) and the ignition system and the regulator

If you see a drop here, your top suspects are the bulkhead connector, the ignition switch connector, and in rare cases ammeter connectors or the ammeter, or more rare, the "in harness splice" which is under the dash in the black ammeter lead

Next, check the regulator ground

Get the engine running at an RPM to simulate low to medium cruise. Since the voltage seems to be running high, check your battery voltage and drop the RPM as necessary to get the battery down to at least 15 or so.

Now, stick one meter probe directly onto the battery NEG post, and the other probe onto the regulator mounting flange. Be sure to "stab" through any chrome, paint, ruse. Again, you are hoping for a low reading, the lower the better, zero is perfect. Any reading here above .2V means you need to improve the ground between battery, body, regulator, and engine

Next with the engine still running, clip one probe onto the alternator output stud, the other to the battery POS post or the starter relay battery stud. If you see much over 1 volt here, it shows the charging line, through the bulkhead, and back out to the batter through the ammeter has poor connections, PROBABLY the bulkhead connector

Please refer to the simplified diagram down the page on the MAD article, which shows how this all ties together.

If the voltage drop tests do not show abnormalities, and charging voltage is still high, first take the battery and have it load tested, and look for bad cells

IF that seems OK replace the regulator

PLEASE buy a good one which are not cheap. Either Standard Motor Products VR-128, or Echlin/ NAPA VR1001. Neither looks like your old one, but they wire in the same.

Another route you could go, since you have a late isolated field alternator, is to add ONE new wire, and use a 70/ later regulator.

Roadrunner - thanks again for the help.so you feel like I'm ok with my hook ups?(newer alt 65 amps one grounded fld and line from batt stud to starter relay)your 1 st test I get just under 1 volt from batt to ign connection on vr.will do some more tests when home tonite.i know I need to to the mad bypass,but not too sure of my soldering skills.thanks,David.

There may not be anything wrong at all. Give it a day or two and recheck it. If that battery has been on the shelf a while, it's possible that it's low on charge. If it is, the charging system will put out more than normal until the battery is completely charged again. So recheck it in a day or two and see what it looks like then.

if its charging, obviously not the alt, old timer taught me this, ANYTIME SOMETHING STUPID HAPPENS-- ITS PROBLY A GROUND.
the old setups use a ground for the reference, (new cars use an extra wire with 5v on it, thus the 3 wires on all your sensors.....) if you get a bad reference---you get a bad signal. I had 2 grounds on my 76 DD Dodge truck, and it started charging @16 volts, added a 3rd ground (even though my fantastic brain knew it wasnt that) and POW, fixed it instantly, Replace or double check the grounds, just cuz it looks good, dont mean it is, good luck.

thank you for the input.i have gone thru all the grounds i can find and filed down to metal on each one.i added a ground from neg cable to radiator support.one off manifold is good.you are probably right though.any others i should look for that i'm missing?

Do you have a large ground strap from the engine to the chassis?

RustyRatRod said:

Do you have a large ground strap from the engine to the chassis?

Click to expand...

Rusty - to be honest i did'nt even know to look.any idea where i should look?i see the one from intake to firewall.should there be one at bottom of engine also?thanks

The one from the intake to the firewall should be sizeable. I always prefer more than one. Because without them, you'll end up grounding through shifter linkage, speedometer cable, anything that current can find to ground will be used.

ok.i'll see if i can find a place to add one to chassis just to make sure

RustyRatRod said:

There may not be anything wrong at all. Give it a day or two and recheck it. If that battery has been on the shelf a while, it's possible that it's low on charge. If it is, the charging system will put out more than normal until the battery is completely charged again. So recheck it in a day or two and see what it looks like then.

Click to expand...

This is the second time I've caught you posting this and it is NOT CORRECT. Battery charging voltage DOES NOT EVER go above the regulator setting in a properly working system, and ESPECIALLY if the battery is low. The OP said "16 volts." This is COMPLETELY out of line and should NEVER be considered "normal" Anything much above 14.5 and certainly above 15 is NOT normal

- - - Updated - - -

Bee383 said:

Roadrunner - thanks again for the help.so you feel like I'm ok with my hook ups?(newer alt 65 amps one grounded fld and line from batt stud to starter relay)your 1 st test I get just under 1 volt from batt to ign connection on vr.will do some more tests when home tonite.i know I need to to the mad bypass,but not too sure of my soldering skills.thanks,David.

Click to expand...

Are you saying you have already bypassed the ammeter?

I believe your hookup with the later alternator/ early regulator sounds OK from what you posted, but do the voltage drop tests, and if that shows no problem, then have the battery tested and if it's OK replace the regulator

I'm betting on voltage drop (low voltage on ignition run buss) or bad regulator.

440roadrunner said:

This is the second time I've caught you posting this and it is NOT CORRECT.

Click to expand...

Ok.

Does the regulator have two wires or three? If the car is showing battery voltage at idle and 16V cruising the voltage regulator is not doing it's job to kill the field circuit in the alternator.

Jeremiah said:

Does the regulator have two wires or three? If the car is showing battery voltage at idle and 16V cruising the voltage regulator is not doing it's job to kill the field circuit in the alternator.

Click to expand...

Jeremiah-2 wires on the regulator.i put the older style regulator back on and ran an extra ground wire from it and it seems like everything is back to normal.thanks for the reply,david

Excellent. Please let us know if you have any trouble and happy cruising!

you can get a thousand amperes alternator if you want, but will just provide the car demand. If car demands just 30 amperes, the thousand amperes will never came out from alternator, just those 30 amperes

The big problems began when you got a car not able to feed at iddle, making to discharge the batt because was the only source available to feed what alternator is not able to feed. Then reving up, the power going back to the batt for long time periods on weak conectiosn is what burnts everything around. That back and forth load coming and going is the big defect on Mopars

if you get an alt able to feed all the car requirements without suck from the batt, even the stock wiring will hold, although get a help from an extra wiring running from alt up to ammeter is a big help to save the weakness on bulkhead terminal.

Then the next big mistake since ever was feed all extra equipment from battery ON AMMETER CARS. This was translated by ammeter like a charge from alt to batt when revving up where really mostly of the load could actually be used to feed the extra equipment wrongly sourced up... this produced a higher stress on an already stressed system by a low alt capacity alt.

NO NEED TO PROCEED WITH MADELECTRICAL MOD. They post there a wrong statement. They say whith their mod you are moving out the main splice to the starter relay stud WHICH IS NOT TRUE... the main splice will be FOREVER inside the cab. There is no a way to change that unless you make a heavier modifications on wiring

Nacho-thank you for your reply.by running the wire from alternator to starter relay without doing anything else for right now,am i helping anything?i will bypass the ammeter when i get some extra time.thanks again,david

jumping out a wire from alt to starter relay makes shares the load required by the car by both sources in both wires. Helps? yes, kinda off, just a little bit, but you are jumping out the ammeter. You'll barelly will see the ammeter needle moving ( if actually some move ) and IF BY CASUALITY MOVES ( what practically won't happen) be sure will be a wrong reading.

Jumping out the charge system with that wire, will actually saves from the loads going come and from the batt throught bulkhead and ammeter, and practically sourcing all the car by just the black wire terminal on bulkhead. Just a little bit of the load could go from the red side of ammeter IF THE LOAD FINDS more resistence on bulkhead black connection than the ammeter and red bulkhead connection together.

Is like the water. All the higher pressure will go throught the bigger and easier path it finds

here is how the ammeter systems works on our cars:
http://www.dodgecharger.com/forum/index.php/topic,33574.0.html