The Stovebolt Site Forums The Shop Area The Electrical Bay Voltage Regulator

There is an interesting thread regarding ammeter vibrations, elsewhere in the Stovebolt. In order to not muddy that informative discussion I’ll start a new thread.

I am learning how to do all this stuff as I go. Further along the learning path than I was, but much more to go yet.

I am trying to complete the wiring on my ‘46 Chevy 1/2 Ton. It is being converted to a 12 volt, using a new wiring harness and keeping the generator. The generator has also been reworked to be compatible with a 12V system. The voltage regulator is a 12V Delco. I have added fuses as recommended: 30A at 10ga wire leading from starter to ammeter, 30A fuse at light switch, and 15A fuses at each the electric wipers, cig lighter, and turn signals.

The problem: The 30A fuse on the wire leading from the starter to the ammeter blows out immediately when the battery cables are attached. The previously working ammeter, per test, no longer registers at all. I prefer to keep the ammeter instead of changing to a volt meter, as some do otherwise.

I am uncertain where to go from here to troubleshoot this problem. Already checked and rechecked was all wiring for loose connections. The harness is new, as indicated, and there are no frayed wires. The voltage regulator was used, but functional, based on having used it for engine and brief driving test runs. However, none of the accessories or light switch were connected at that time.

I understand from the thread referenced above grounding the voltage regulator is necessary. I had previously assumed the regulator/firewall mounting bolts would suffice. I need a better understanding of where to add more grounding, the old Delco Shop Manual shows an external screw for use as a ground lug. The regulator I have doesn’t have one. Will adding a wire from one of the regular mounting bolts and the other to the generator bracket mounting bolt work?

Should insulting washers be used when mounting the ammeter to the gauge cluster? None were used, but in thinking through this problem I have wondered.

I understand the polarization of the generator is needed, as well. But, as indicated, that can’t happen with the fuse blowing as fast as it does.

Thanks.

᠁᠁..with the fuse blowing like that, you have a definite , solid short to ground. Use an ohm meter with neg lead connected to frame ground and just start following the wiring from the generator. At the regulator, you'll see some resistance to ground....about 40 ohms...thru' various coils and that's normal. You should never see 0 ohms to ground. 0 ohms = dead short. If you see 0 ohms, start removing wires until the short disappears. With a new wiring harness, chances are it's a wiring error rather than a frayed wire touching the frame.

Just an alternate opinion:
You can play with all that wiring, ammeter and all those contacts and problems all you want. When you get tired, throw it all away and get a modern alternator. Converting to 12V and keeping all that claptrap is false purity.

bartamos, while your advise would normally be 100% right on, in this case it’s not doable. Sparky is a high quality restoration project and an alternator would be totally out of place. When finished, unless you are a highly trained show judge you will not be able to tell anything has been modified. How do I know this you ask? I’ve been privileged to visit Sparky in his natural habitat (the garage) and have a first hand tour by his owner. Testing for dead shorts is the way to go. One wire at a time, slow, steady and thorough will yield positive results.

This is what he has done: Quote from another post.
"I was curious because I want to use the Halogen bulbs on Sparky and have already added electric wipers, turn signals with emergency flashers, LED tail lights and a cigarette lighter for use as a GPS or cell phone charging port. In the process now of tracking down the power usage for some of these. But, it looks so far like the power draw buget will be within the 35 amps available. This will be a 12volt system with the generator modified to 12volt".

So that's where I am coming from. It's just another "makes sense" thing to do an alternator to an already nice altered truck. Makes no sense to keep the old charging system. None whatsoever.
In one way it's none of my business. In another way, everything on here is my right to opine. I did say "alternate opinion". It may or may not give a person pause to ponder. "Quality" in the sense of purity is gone. Quality in the sense of precise, well done, original and modifications, is being accomplished. I am on no way disrespecting the truck and owner. Stovebolt is a forum for discussion. When I see a person struggle with old technology for no reason, I recommend update. I am a restomod type mostly. Sometimes I see "closet" restomod people. Maybe it's a stigma here.

My motto: Put on an alternator, get rid of the gen, the VR, the ammeter and all the connections and put in an idiot light. When it lights you will see it. It means something is wrong. No needle watching. If your battery goes dead. Get a jump and go home....................that's kind of a long motto, aye?

᠁...just as anside᠁..what is a generator " modified" for 12 volts ? Seem like it's either a 6 volt gen or a 12 volt gen but not a modified 12 volt gen.

gee Bartamos᠁᠁..."claptrap" is a bit harsh.

It just means too much wiring, contact points, terminations, things to go wrong, old technology, less reliable, in an already modified electrical system.

I will amend claptrap to.............. "possible aged cumbersome system which obviously is giving trouble and hard to analyze".

Some guy I used to work with used it a lot during design discussions. It does not mean crap or anything like that.

My experience with new wiring is limited to just two restorations, my COE and my '37. Both are stock restorations. Before I placed the battery in the COE I used my $10 ohmmeter and tested the the battery leads. Oh oh, I thought I had a short, but it was only a light switch in the on position. With everything off, I had no continuity and safely placed the battery. My next project was my '37 and when I did the same thing I had continuity, with all switches off. Long story short I found the tongue of the windshield regulator touching a post on the headlilght switch.

The point of my story is to avoid frying your expensive harness or starting a fire when doing major work on a wiring system, use your cheapo meter on the battery leads to be sure hooking up that battery won't cause you serious grief.
Kent

47chev, it’s a 6 volt generator taken to a generator shop and the 6 volt guts changed to 12volt. Used to be quite common but now days you can’t find a generator shop. 🛠

Ok
Just completed testing all wiring as 47 chev suggested in his first reply. There were no grounding issues in any of the connections. The process used was as was suggested.

Regarding the generator, it was taken to a local shop that specializes in alternator and generator repair. They have retro fitted 6 volt generators to 12 volt many years. I have used one of their retrofitted 12 volt generators on my ‘37 for going on 15 years without any problems.


That “light switch on” thought will be checked. I previously did check to make sure there wasn’t something unrelated to the needed wiring causing the problem.

I understand the alternator conversion preference by some. In fact I have one I considered using. I may yet, but I want to continue learning more about all this stuff and crazy as it may be, I enjoy that more than watching the grass grow.

The online old car manuals will help. Back then, the engineers were so proud and exited about electricity in an auto, that they practically wrote a text book about every aspect of it in the shop manual. As the years went by, less and less education in those manuals. More troubleshooting and R&R.

http://chevy.oldcarmanualproject.com/shop/1942_47/index.htm
http://chevy.oldcarmanualproject.com/shop/1947truck/index.htm

Back then, mechanics took enough pride in their work to demand enough information that they could actually fix things. That sort of attitude started going out of style about 3 generations ago. Now, all we have left for the most part is a bunch of "wheelbarrow mechanics"- - - -guys who roll a wheelbarrow full of new parts up to the job, and start swapping stuff until the problem goes away. Once a part is installed, it's got to be sold- - - -whether it was needed or not!
Jerry

As bartamos posted, here is the voltage regulator section in the 1942-1947 Shop Manual.

I think it starts out with the earth's magnetic fields and how they interact with the solar wind......then eventually to voltage regulators.

hmmmm᠁...no shorts to ground ? And still instantly blowing 30 amp fuses ? I just consulted the Ouiji board and it said check around the cigarette lighter. Whatever it is, you're gonna learn A LOT from this.

bartamos is not joking - go to the beginning of the Chapter that I linked-to, above.

47 chev
Ok will also check the cig lighter, again. Thank you!

Tim and Bartamos, will also do as suggested. Thank you!

No need, fellas to get “shorts” in a wad over any of this stuff. Take a deep breath, help, and learn...and maybe we all leave a trail for some poor soul long after we’re all gone to carry the hobby forward to a new generation. Peace

HA.....46 Sparky...very deep and philosophical, but I'm pretty sure NONE of this will be noted by poor souls long after we're gone. This will ALL be buried deep in the sands of time. On a hard drive. Full of sand.

᠁᠁᠁...my suggestion was to check for shorts starting at the Generator, but I like Lightholders Dad's idea better of starting at the battery and working back into the wiring.

Will do that too. I recall having done that, but my notes don’t reflect it. 🙄🤪🤬

Interesting problem. So the volt/ohm meter reads no shorts in the wiring, sounds like component troubleshooting is in order....
If I read the problem correctly, the 30a fuse blows immediately as soon as the battery is connected. IF thats correct I suggest the following:

Disconnect both leads to the generator and ensure that they do not touch each other nor any other surface.
With the battery positive disconnected, install a smaller amp fuse, 10, 20 etc., it doesn't matter for this test as the engine won't be started and the charging system won't be operating.
Connect the battery, does the fuse blow?

If yes, the problem isn't with the generator continue component troubleshooting to the regulator and associated wiring.

If no, you've got a problem either with the generator or wiring to it, troubleshoot accordingly.

IF you try this, check back with your results.

re. the linked manual, I'm going to continue to read the opening section that describes electric theory, I kinda dig such compositions....

Why is there a 30 amp fuse between the starter and the ammeter in the first place? That doesn't make good nonsense. If that circuit is fused at all (it wasn't originally) it should be a maxi fuse with about a 60 amp rating or so. The only reason it needs to be there at all is to prevent wire burning in case of a dead short. Which, by the way, you probably have. While you're troubleshooting, temporarily install a 40 amp circuit breaker instead of that fuse- - - -resetting it with a push button every time it pops is a lot cheaper than buying fuses by the dozen.
Jerry

Read the Shop Manual Chapter as suggested. Will need to study it more to better understand some of it.

Didn’t get much time on the project today otherwise. But, did check that the lighting switch was off. Also, disconnected the cig lighter wiring completely and reran the test as 47 Chev recommended yesterday, same result with resistance shown. Also confirmed there wasn’t a problem created by a body part as described by Lightholder.

Checked the generator and voltage regulator as recommended by Volfandt. Both tripped the circuit breaker HRL suggested using.

Regarding the fuse placement: it was used at that point in the wiring after having seen one used on another guys truck at a show. He said he’d done it as a quick disconnect and theft deterrent. Said he’d used it that way for years without any problems. The light switch that came with Sparky didn’t have a fuse buss, despite one being shown in the Shop Manual wiring diagram. So, I figured that location from the starter to the ammeter would work. Since this wiring troubleshooting learning challenge began, an inline fuse was added at the light switch.

Thanks to all for helpful suggestions.

Have you considered the possibility that the ammeter is shorted internally? Disconnect everything attached to the ammeter EXCEPT the wire to the starter cable, and see if the breaker trips when you connect the battery cable. If it doesn't, them touch one wire at a time of the ones you disconnected until you find the circuit with the short. "This ain't rocket surgery"- - - - - -all it takes is a little bit of logic and common sense!
Jerry

I will try that testing tomorrow. The ammeter does not register at all now.

Ballast resistor used?
Did you get your answer about if and how to ground VR?
You can bypass the Ammeter like Jerry says, if there are fuses inline. It's a combination meter, hot wire terminal block and a bad idea the way it was wired.

You can also take the whole charging system off line to get it started. Take the belt off.


I assume this is not a shunt problem.

Also: this would not be the first time a fabulous 12V generator rewire company screwed up.

I forgot what your problem is right now? 30A fuse blows when battery cable attached and ammeter does not work.

Sometimes it's not safe to increase fuse amperage. You can send the failure "down the line" to a component.
It seems like the 12V battery is shorting to ground somehow.

You have to find out what is shorted or pulling so many amps to blow a 30A fuse. Can't think of anything pulling 30A with nothing on....so it means you have a dead short. That does not mean you have a frayed wire or a cut wire, it means YOU have wired something bass-ackwards. Rethink and recheck the work you have done. Be sure you know EXACTLY which terminal on a component is for HOT and which is for ground and so on. Check all grounds you have added to ANY component. We are not getting our shorts in a bunch we are trying to fix your shorts before you blow your shorts off. The 46 WILL be sparking. Some of us try to cut to the quick to find a fix. We try to filter thru the posters words for clues.
Good luck and let us know what you find out. It will help the next guy.

Connect a heavy wire, or maybe a jumper cable, from the starter to the ammeter. Install the battery cable and stand back. When the smoke clears, the shorted circuit will be very obvious. Suggestion- - - -have a good fire extinguisher handy! Otherwise, use a little logic and common sense and find out where the incorrectly connected circuit is. Quit obsessing about the generator- - - -it ain't the problem if the regulator cutout relay points aren't welded together.
Jerry

I like Jerry’s Suggestion, it’s like - okay we are done talking, time to act! Made me lol
Effective too, it’s not like there is going to be an uncontrollable fire, but you will know the problem.
-s

FINALLY! Got it done!!!

Found two problems.

1) The turn signal wiring was wrong!

2) Found that a ground strap was left installed some 18+ months, after completing the engine testing and before the cab and other sheet metal was installed. I recall thinking it needed removed, but obviously it wasn’t. That’s what I get for working on this project piecemeal over 10 years and NOT keeping enough notes and remembering to review them!

Lots learned and thanks to everyone that offered useful and constructive help.

The Sparky thanks you as do I.

I don't get why a ground strap was causing it but glad it's fixed.