Alternator low voltage problem.... my nightmare

[NickOReilly]

Hey guys, seeing if I can get a little help... Sooooo, I have a '70 or '71 440 (cant remember) put into a '67 Satellite, trying to figure out why the low voltage. Put in a new Evans harness, electronic ignition, new voltage regulator, new single field alt, took it back and had them test the new alternator to be sure,... anyhoo with the engine idling and the multimeter on the alternator lug, I show 11.8ish volts, it will climb to 12.5ish when revving up,... my battery is a bit low at 12.2 with the engine off, but running I see a climb on the battery when revving up. So not being too experienced, i figured this seemed about right, went for a 30 minute cruise, tried to restart and dead as a door nail. Sooo I started thinking, I replaced the 4 groove crank pulley and replaced with the 440 Source double v crank pulley and 440 source water pump pulley. The 2 groove crank pulley is a little different, the inside alt/water pump groove being about 1/2'' smaller radius as the original.... the smaller crank pulley causing me to lose a few rpm's from my alternator??? Causing me to come up short? Anyone had any issues like this? Or is my problem elsewhere??

 

[bigmanjbmopar]

Depending on The brand it is it will not charge at idle you have to get it over 1500 I think, I have a 100 amp tuff stuff one wire specifically because I do tunning at idle and didn't want to drain the batt. If parts are good it's because your alt won't charge at idle try changing or just reving higher.

 

[NickOReilly]

But after 30 minutes of driving around, I expected my battery to either maintain or to be charged more. I wasnt running headlights, and I wasnt just idling around ;) Immediatly tried to restart, and the battery was dead, didnt even try to crank, even though my amp meter showed around 12 the whole drive.

 

[bigmanjbmopar]

I went back and read over your post and didn't see anything about the battery being replaced yet? This sounds like a classic case of battery fried but alt gives it enough to run for a minute. some shops have crap battery testers make sure you go to one you know that works or just buy a new battery and try that. are you still using the ballast resistor as well? is it hot? real hot?

 

[NickOReilly]

So I hooked up my multimeter to the stud on the alternator, set it so I could see it in the drivers seat. At 1500 rpm its putting out right around 12.20, at idle around 700rpm around 11.80, hold it at 2000rpm it puts out around 12.60, switch my headlights on and it drops to around 11.7... So its not handling a load I gather, does this mean my regulator is bad? Sorry if these are dumb questions. And I was under the impression my alternator should be putting out 13-14 volts when wound up a bit, is that not true? Or do I not know how to test correctly? I also put a jumper from the field terminal to ground and no jump in voltage... Im out of ideas.

- - - Updated - - -

It was a new battery 6 months ago, but Ive run it down quite a few times over the last couple weeks while fighting with this, and have had to recharge it. Yeah its a new ballast resistor that came with the elec ignition kit, and yeah it get pretty hot.. its supposed to right? Thanks alot by the way.. really appreciate it

 

[nm9stheham]

Your alternator and voltage regulator are not working at all. The small rise in alternator is likely due to residual magentism in the field windings and not due to the VR pushing the proper amount of current through the field winding. You should read around 13.7 to 14.3 volts at the battery at fast idle (1500 prm). It will be a bit lower with a battery partially discharged, a bit lower when really hot and a bit higher when cold.

Your original description caught my eye; if the alternator has one field connection on the back, then it is not the right type to work with the newer flat pack style of VR. Do you have the flat pack VR with the molded connection, or the older square block style of VR with the screw lug connections? If the flat pack type, the alternator will have to be changed for a later one with 2 field connections on the back, and some re-wring done. You can wire things up to use the later alternator with the earlier or later VR, but not the early alternator with the later VR.

Let us know what style of VR you have first. Also, make SURE the VR has a solid ground to the chassis and you have a good battery ground to the chassis too. Scrape off paint if you need to get a good ground contact between the VR case and chassis.

Alos, charge your battery overnight or for a minimum of 6-8 hours before trying again.

If you have the early alternator with just one external field connection, then the other end of the field winding is internally grounded. To do a full field test on the early alternator, you don't jumper the field to ground; you jumper it to the battery +. Try that for a moment and your voltage should rise way up, to 15-18V. Don't leave it on long and make sure the battery is conencted in well.

Sent you a PM.

 

[bigmanjbmopar]

I'm sure you know this but new one wire alts have a vr built in. My tuff stuff one does, so I was able to loose the ballast and vr on the fire wall. I think you fried your battery I wouldn't mess around and just get a new one. ballast get hot so long as it isn't melting the paint you good

 

[Badvert65]

All good information. Your issue sounds like either an alternator with some bad diodes in it, or the Voltage Regulator is not working. Make certain your voltage regulator is well grounded. FYI, charging systems do NOT have/use a ballast resistor. Also, there are basically two styles of alternators:
Single Field- one 'bolt on' battery connection and one 'plug in' connection (to the voltage regulator) and uses a Voltage regulator that looks like this (square black box):

Dual Field - also has one 'bolt on' connection for battery but has two 'plug in' connections to the voltage regulator (the regulator will make one of these 12ish volts and the other will be 'regulated' by the voltage regulator.
Voltage regulator looks like this:


You should try this, with the car running disconnect the battery. If the engine dies, then you definitely have a problem with the charging system. If it keeps running, your battery is suspect.
If this test indicates your charging system is faulty, your problem is either alternator and/or regulator (assuming that your wiring is good).
You can have your alternator tested but it is only good if it is 'load tested'. Voltage regulators can't effectively be tested, much simpler to replace with a known good one.
First thing would be to identify which style alternator you have and which style voltage regulator you have, You can't directly interchange between the two, even though you can easily bolt in either one to the same mounts.
Post your results to this and we can probably narrow things down from there.

 

[NickOReilly]

Hey thanks guys for all the input, yeah Ive got a new single field alt (took it back to the parts store and they load tested) and the older style mechanical VR, I mounted the vr on wire wheeled bare metal with a star washer on each bolt, so i assume its well grounded. My battery is grounded to the block and the block has a ground strap to my firewall, also with a star washer. Ill try the CORRECT full field test when I get home.

And no I didnt know that Bigman, had no idea the new alt had a VR inside. Probably good to know.. and yeah Ill check into my battery, see where it is when its fully charged.

Thanks alot guys for a ton of good info, you guys rule

 

[NickOReilly]

So I ordered up one of the Wells 704s and it worked like a charm, fired her up and it went right to 13ish volts at idle, and rolling down the highway never gets much over 14... if only i would have come and scoured the site sooner!! I wouldve saved myself a weeks worth of f****ng around! Thanks again nm9 for all the help, i really appreciate it Mark! Once i get more than 3 seconds Ill get some pictures up and update my thread.. been a crazy busy summer

 

[A383Wing]

PS: the ballast resistor has nothing to do with the charging system

 

[nm9stheham]

Good deal, Nick .... crazy that the other 2 VR's were so bad. Were they new from a parts store?

BTW, I see an idea in a post above to disconnect the battery while the car is running; don't do this. It is a good way to damage/destroy a VR or some alternator diodes and possibly other aftermarket electronics like an ignition system. The battery serves as what is called a 'ballast load' in the system and absorbs spikes in voltage. Disconnecting it while running can cause a high voltage spike in the system that damages components.

 

[Sixpactogo]

I would look at the battery as the culprit here. The reason I say that is the fact that you started the car and drove it for a while and the battery was dead. That tells me you have a dead cell in the battery and it will not accept a charge. I had that problem years ago while in the Navy. My car could sit for a month while we were out to sea. I would be able to start the car after sitting a month but after driving it for 15 minutes, it would not start. The dead cell was on the first post from the neg post and once I shut the engine off, the battery was dead. If I let it sit for a period of time, the dead post would equalize with the other 5 cells and it would start again. I bet if you check your battery cells, you will have a dead one. It may explain the low voltage while running the engine because the regulator does not recognize the battery in the state it is in.

 

[BDubz]

Hello Nick,

What alternator did you order? I have been having the exact same issues that you have described.

I have a '68 Satellite with a HiPo 383.

Regards,
Brian