The Stovebolt Site Forums The Shop Area The Electrical Bay Alternator problem

Just got my 1938 HC running. New 235 ('54 model)
converted to 12V. Turn signals and modern conviences. I am using a GM 12V alternator and looking for help on how to connect it to the eletrical system. I re-wired the truck myself and everything works great. The alternator has a large threaded terminal on the back side and two blade type terminals recessed into the housing on top of the unit. What to I need to hook up where?

You need to do a search because this has been discussed dozens of times. You'll also need to know which way the two terminals are oriented to determine what alternator you have.

lobo49,

As Cletis mentioned, this subject has been discussed many times. This doesn't mean it is less important each time it is brought up, but it requires quite a detailed 'how to' description.

If you can do a search using the little icon at the top of the page...maybe use the phrase " alternator wiring" or such, you will learn a whole lot.

Then you can come back with specific questions. There are some very good schematics in the archives that show exactly how it is done. These will pop up in your search.

You seem very knowledgeable about wiring, so maybe one of the wiring diagrams you find will answer all your questions.

Stuart

Wow is this alternator mounth already? Seem it was just yesterday that it was here. Oh, it was day before yesterday, nevermind. Go to tech. tips on this site and look it up. If you have any question after that. SOUND OFF!!!

Thanks gys for your direction. I'm fairly new to Stovebolts, having cut my teeth on Model "A"s. But once you wear a BOWTIE, you'll never go back!.

Looking at the back of the alternater the blade terminal that is counter clockwise to the other goes to the accessory side of the ignition switch. The other one is jumpered to the terminal on the back which also has a 10 guage wire that runs through your ammeter to the battery. If your alternater has a tiny #1 and #2 beside the slot with the blade terminals then #1 goes to accessory and #2 to the terminal on the back. Many of the early switches don't have an accessory terminal and so you have to use the ignition terminal. In this case you have to put a diode in the wire to the #1 blade or else your engine won't stop running with the switch in the off position.

see ALL of these links
you can also go to search and just type in under electrical ----- alternator.


http://www.stovebolt.com/bboard/cgi-bin//ultimatebb.cgi?ubb=get_topic;f=3;t=002234#000000

http://www.stovebolt.com/bboard/cgi-bin//ultimatebb.cgi?ubb=get_topic;f=3;t=002217#000000

http://www.stovebolt.com/bboard/cgi-bin//ultimatebb.cgi?ubb=get_topic;f=3;t=002186#000000

>> http://www.stovebolt.com/bboard/cgi-bin//ultimatebb.cgi?ubb=get_topic;f=3;t=001966#000000

>> http://www.stovebolt.com/bboard/cgi-bin//ultimatebb.cgi?ubb=get_topic;f=3;t=001857#000000

Lobo49, received your private message and was instructed to reply through forum. My shop is so far in the sticks it wastes half a morning or afternoon to go after a part so here's what we do for the needed diode. Take a junk GM alternater, internal or external regulater makes no difference, and punch out several diodes. You can see some of from the back of the housing--about 2/3's the size of a dime. After it's out and the lead is snipped take a test light and find which way it lets current pass. Put the test light clip on the negative battery post and touch first the "can" end of the diode to the positive post with the test light probe touching the snipped off lead. If it lights the flow is from the can to the lead and visa versa if it doesn't. Double check by touching the lead to the post and probing the can end. (I suspect diry minds are at work). Once the flow direction is found solder a lead to the can with a minimum of heat and cool immediately, then check again. Now install so the electrical flow is TOWARDS the alternater. This will let the alternater excite but not backfeed into the ignition. Tape off the diode since it is "hot". The wire will have a bump like a snake that's swallowed a rat but it works everytime. If you live somewhere near civilization you can go to a generater/starter/ alternater rebuild shop and get diodes, they have bins of them. I used to go to Radio Shack but the last trip there was told they no longer stock component parts--a shame.

coilover,

Very ingenious. I guess living in the sticks can lead to all kinds of creativity.

Stuart

Tnx. have visited all the links suggested. Have a source for components (resistors, etc.) Just need to now what size/rating diode to get. I understand the anode/cathode orientation for proper flow, but just need a suggestion as to what "size" diode.

lobo49,

I found this...it is a quote from another site!


One diode, something like a 1N4001, available from Radio Shack. This is rated at 50V and 1 amp.

This number has been mentioned before on this forum...pretty small and quite inexpensive!

Stuart

Tnx Stuart. I think we are on track now to put this effort to rest. Von