Voltage sensing alternator

gulfdawg

gulfdawg

Member
I am currently upgrading the electrical system on the truck. I would like to upgrade my 10si to a 12si 100 amp alternator. I have done a good amount of research on upgrading the wiring to handle the increase in amperage and to eliminate the amp gauge. My question is, lookin at the IH schematics for my truck it appears the voltage sensing wire for the altenator comes from the ignition switch. Would I be better off moving it to the battery feed connector or the remote started solenoid, Ford starter relay, I have already installed? The reason I believe I need to relocate it is right now my all lights go dim at idle. As soon as the rpm's go up they get brighter. Anyway I think I am
on the right track, just looking for some support. Thanks justin

my truck is a 1974 100 4x4 no a/c, 63 amp delco alternator. I dont have alot of electrical upgrades now excecpt, ignitor, msd 6a, electric fans, h4 headlights.
 
Ok, looks like I am already wrong. The sensing wire from the alternator terminal 2 goes to the starter solenoid on the starter. Which is still in the stock location on the starter. The Ford starter solenoid I installed simply serves as a relay for the start signal from the ignition switch. That works quite well. So I still have the same question, should I move the voltage sensing wire to the battery feed connector or simply to the Ford solenoid. Maybe I should take a break and let this all soak in.
 
I just upgraded my alternator to the 9si. Mines a 74 s2. Try bumping the idle up a notch and see if it solves your problem.
My rig still has the amp meter and the original sensing wire in its factory location.
I have noticed that with alternators from the major auto parts stores dont seem to function as well as the ones I have built by the local rebuilder. I had the same issue twice. Took them back and went to the local guy. No more regulator issues.
Just my .02 worth
 
With the "load" you have described, I see absolutely no reason to upgrade the alternator other than possibly have a 10si "built" that will produce an honest 80 amps or so.

Any alternator will only produce current based upon it's specifications of the voltage regulator unit. Most of the mass-merchandiser alternators simply use junk internal components, more especially on a basic unit that is over 35 years old. Work with a local rebuilder to provide a decent quality regulator assembly that will provide current within the normal operating capacity of the entire vehicle system you are using.

I totally agree with tow...if you want a decent alternator, have one built from a junker. I don't even screw with 'em myself anymore, it's just never worth the effort.

By installing the additional starter relay, you have only modified the starting system to be a bit more stable and possibly eliminate the "hot re-start" issue. There is absolutely nothing wrong with the wiring system we use for that and it places a "hot spot" for the b+ termination is a convenient location for adding auxiliary systems and components.

If...someone has a true need to eliminate the oem-type ammeter, I don't know what that is! I see no reason to do so at all. If...someone needs a higher ampacity instrument, then simply drop one in or use one that incorporates a "shunt" device as part of the install.

I want both an ammeter and a voltmeter installed on my rigs so I can "see" the electrical situation all the time!
 
I appreciate the advice from you guys. It was cheaper to take the chance and go to the wrecking yard this weekend and pick up an alternator. I was able to find a 140amp cs-144. The alternator bolted right in after swapping the pulleys. I made some wiring upgrades and did find some shady wiring from the po. At idle with the fan on high, and headlights w/high beams on it was producing 70 amps at 14.5 volts. It would have been easy to have a 10si built but money is tight and the wiring upgrades needed to be done anyway.
 
There you go a cs144, no issues with extra lights, winch, fan and what not. :d but now you are going need to upgrade the charging circuit as the stock 10ga wire will darn near melt. I upgraded mine and made several changes. I too also have the Ford starter relay, plus the bright lights kit, and many other items too.

I mounted a distribution block off a circa 1990 chev pick up on my fire wall. They are located on the pass side fire wall of the chev pickup if your looking, plus I take all the fuse-able links too. I also pulled the 6 ga charge wire off a Ford taurus and a 6ga wire with fuse-able links off a Ford mini van.

So I have a 6ga wire coming off the alternator to my distribution block and a 6ga from there over to the Ford solenoid, which has a 4ga wire heading back to the battery. I ran the alternator sense wire up to the distribution block. Plus added a new alternator red light into the dash.
The bhc wires that used to take the full amp load from the alternator are just connect to the dist block, so I jump the amp meter and added a volt meter.

It's pretty easy to make the change to go back to the stock alt if needed in a pinch.

I can post up some drawings or pic's if you like. I would make sure you have a ground wire from the engine block back to the battery as electricity travels in a loop. I also upgrade my body ground wire.

Edit.. Not sure but babs might have a work day coming up in a month or so.
Plus I want to thank mr mayben for all the hard work he has put into this electrical forum.
 
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dr. Mayben ihphd said:
with the "load" you have described, I see absolutely no reason to upgrade the alternator other than possibly have a 10si "built" that will produce an honest 80 amps or so.
Click to expand...

If you take a 10si case and have the windings added to induce more current that will result in more heat do you also need to address the air intake on the back of the 10si case?

If I remember the thermodynamic properties as related to energy exchange (loss of efficiency) in an electrical system it includes squaring the amperage.. And that means that 80(^2) amps creates much more heat than 60(^2) amps.. Or is this just over thinking/engineering?
 
Thats why it helps to have the large case alt. The bigger around it is the more heat it can dissipate. The cs144 is a nice alt as its a large case and makes the most amps at low rpms over others out there.
If your going down the freeway at 3,000 rpms the stock alt is plenty.
 
Just finished up the wiring last night. I ran 6 gauge wire from the alt output to the remote solenoid. I also installed a remote power lug, I was able to get one off a tractor at work. With all the wiring finalized I took it out for a test drive. The volt gauge was just under 15 volts and all the lights were bright and never dimmed. Great upgrade with room to grow.
 
Add the brightlights kit and you will wonder how you ever got by without it. I like the nice water tight FI relays out of circa 1990 GM cars. Buicks, caprices. Yes the oem parts are better then most parts you can buy new. Some look down on junk yard pulling, but there are some nice parts out there.

I mounted the relays ( you need 2 one for low beam and one for high) behind the drivers headlight. Theres plenty of room for 2 relays. Note: I take the bracket the relays are mounted too from the car I pull them from. I don't change the stock wiring at all. I just use a spade lug to plug into the stock headlamp socket and use that power to turn the relay on and off. You do have to run a new fused 14ga or better wire to be switched by the relays. I bought some headlight plugs at the store and soldered them to the output of the relay. You need to also pull that wire over the other side to power the other headlight.

Did you run the sense wire to the Ford relay? Did you also add a lamp.


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I ran the sense wire to the extra power lug. The alternator output, 6 gauge wire, was ran to the Ford relay. I installed a resistor into the excite wire that runs to the ignition switch. The alternator requires 35 to 350 ohms of resistance and it only had 14 ohms. I did not add a light, I would have liked to but didnt find a light that I really liked. It all seems to be working good.

That is a sweet spot to mount the bright light relays, there is a ton of hidden room behind the headlights.

If I can find my camera I will snap some shots. Let the wife borrow it and now it is gone.
 
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