cucv 24v alt questions

[jnlperformance]

so ive converted my 62 from vbelt to serp. successfully. now i need to wire the alternators.

on the downside i no longer can mount the old 27si alts. now im in cs territory.

please correct me if im wrong.

to my understanding the only alt that requires the isolated ground is the passenger side alt (this is the 24v alt that supplies 24v via series wiring in harness) they both have isolated grounds but the required one is the 24v for obvious reasons. everything but the start and charge is 12v. they are also internally regulated?? unless i missed it somewhere when pulling the harness out (the entire engine harness is currently out including the cab harness)

on the driver side harness i have 4 wire leads. the large red one is obviously the 12v charging wire. i have what looks to be the 12v ground which is black/white stripe. a brown wire with rubber end cap. what is that? and then the connector end there are 2 more wires red and brown. what do those go to? the gauge set?

on the passenger side harness i have 4 wire leads. 2 large red leads. one of the larger red leads has a smaller lead "crimped" to it with a fusable link. im assuming the large red lead without the extra lead attached is the 12v charging system wire and the one with is the 24v charging system wire and the red lead with the fusable link attached to the larger charging system wire is the 24v ground? then lastly is the connector end with two wire leads, but on this one the leads are red and brown/yellow stripe.

i do have the factory service manuals and the military manual set here in my shop and ill be looking at the wiring schematics and im also going to be testing with my voltmeter to be very very very sure about the wiring before i modify the harness.

but i like to ask around too... so if someone already knows exactly what all these wires are, please let me know.

has anyone else converted to a serp setup while retaining the 24v system. i can buy a "marine" isolated ground cs130 but they are friggin $$$$ expensive. 8 900 dollars an alt. pphhh. no. not happening. ill likely have any modifications required done by the alternator and starter rebuild shop around the corner.

just curious and maybe wanting a little nudge in the correct direction on this... theres a first time for everything and this is my first. anyone have an idea on where i should begin on this?

so lets say i modify a cs130 or any other cs series for that matter, but more specifically the cs130 and cs130D ... i would not need to modify the 12v (as much) as the 24v. how about the regulator? does the 24v 27si with the isolated ground use a 12v internal regulator?

i dont know too much about alternators but after this im sure ill know all about them. im assuming ive got my work cut out for me as usual.

 

[TGP (IL)]

The right Alt. is not 24V.
It see's 24V., but both Alt are the same 12volt isolated ground.
And yes only the pass. side needs to be isolated. In reality the Gov. just used the same on both side for cost,
And parts convenience.

Why the serpentine belt?
Your just trying to reinvent the wheel?

The three belts are the least of my problems.
Tom

 

[MarcusOReallyus]

Just like your two 12v batteries, your two alternators are two 12v alternators, "stacked" like two D cells in a flashlight to add the voltages together. 12v on top of 12v = 24v.

The cab, lights, and all the rest of the 12v stuff is connected "in between" the two "stacked" alternator & battery pairs. The 24v stuff (glow plugs, starter) is connected to the "top" of the "top" battery & battery pairs.

 

[richingalveston]

if you can get an isolated ground alt, it may be your easiest way out, just see if they have rebuild kits and can be rebuilt and you should only have to buy one.

I don't think the wiring harness needs to be modified. your alts need to be modified to work with the existing wiring harness you have or you will not have a true hybrid system. You will end up with two twelve volt systems and I believe battery isolators are needed. And there is proof from some recent threads that running one 12 volt and one 24 volt alt. can cause some battery imbalances. No real evidence of battery damage but something to consider.

In theory, you could mount the second alt. with isolation washers and make the standard alt work, just don't touch the case or it is going to light you up.

I would probably just buy the expensive one if I new I could rebuild it at reasonable price and keep the wiring all stock.

I would like to go with the serpentine system on my new 6.5 but I just have to much else to do than spend the time and money at this point sourcing the parts.

I am just going with all the stock cucv stuff for now and maybe ill switch down the road, Maybe I will find the stock system working fine also and never change.

back on topic, if you are trying to keep it 24 volt with two 12 volt alts, you don't need to change the harness.
Any changes to the stock harness and when other problems happen on your truck, no one will be able to help you here.

Rich

 

[Skinny]

If you have zero 24v systems other than the starter, it sounds like the only two easy options would be to convert over to 12v or just feed the second battery with a solar charger and call it good.

 

[jnlperformance]

 

[jnlperformance]

im very thankful for all the helpful replies.

i thought i was pretty good at electricity but, there is a first time for everything, and this is my first 12/24 hybrid. i aim to keep the stock 12/24 system.

i apologize; when i said modify the harness i shortened my intentions... modify the alternators and modify the harness connection method to alternators if required.

so from what i gather according to the schematic the passenger alternator is the only one that requires the isolated ground. i was partially correct in my assumptions amd i have a pretty good grasp on the system; the connector ends with the brown and red go to the gauges. the only wire i could not identify yet is the brown wire with the rubber grommet on the driver side only. ill take a pik if anyone needs me to.

i do have a few more ?questions - what is a "supressor" in the schematic. two it seems. one as the passenger side ground and one in-between POS TERM BD and NEG TERM BD. i dont remember there being anything like that during the teardown. there was only a wire in-between the positive terminal bd and negitive terminal bd. ? thats somewhat perplexing. you would think it would burn up... and come to think of it... as i was rebuilding alot of the firewall components i noticed there was nothing left of that wire... i dont think it was ever connected when the truck was running before the teardown.

so my plan right now is to just grap a spare cs130 around here and isolate the ground and create a stud post for it, and connect the 12v lead on the passenger side to the isolated ground stud post? and then the 24v line pair (the large gauge red line with the attached smaller red line with the fusable link) to the normal positive charge post. presto? should work? ive been reading around here about how the difference between the 27si ig and non ig are some plastic washers or something? ive never gone into an alternator but im always up for a good challenge.

then all thats left is to figure out which of the four posts to attach the volt meter wires to on the 130. then the tach signal posts.

... at least thats my plan. another would be to buy a rebuild kit and try and mix and match my way there into the smaller 130 casing. ... i dont see that happening... HOWEVER... should i buy 2 of them? is there anything that i would need out of that kit to convert a 130? other than isolating the ground?

 

[jnlperformance]

ok, so after a full nights worth of research i think i have a pretty good grasp on isolating the ground on the cs130, but im concerned about hooking up 12v+ charging from driver side alternator to isolated ground on passenger side. the grounds are essentially connected to the brush holder on the cs130. theres a resistor on "some models" on the regulator in the 27si. maybe im just overthinking this...

the terminals are pretty simple on the 130
l - 12v ignition wire would go here (brown on 27si connector)
p - used for tach lead
f - not used (feild sense) used for an ecm to calculate how hard its working I guess...
s - 12v battery wire (red on 27si connector)

I also figured out what the little brown plug wire is. the ICE/STE tach signal plug? I see where some guys have tried getting a proper signal from it.

 

[richingalveston]

The suppressor is just for electrical noise. Most of them get removed at some point so it is normal for them not to be there. I believe they just go between the case and the output terminal of the alternator and there is no wire from the wiring harness to connect to the suppressor. It just reduces the electrical noise the alts can put on the ground system. It is needed when you have a lot of radio equipment.

I think you may be tearing up some new alts. due to design some cannot be made isolated ground. If you can buy one off the shelf even thought expensive, It sounds like a for sure thing.
If your cucv alts are good, you can probably get 100 each for them to go towards the expensive one.

 

[corelokt]

Can you post a how to about the cs130 mod.?

 

[jnlperformance]

ill do a cs130 mod post if i get it right... otherwise ill be posting a video of an electrical fire and a panicing, angry wife... lol

 

[phil2968]

...a brown wire with rubber end cap. what is that? ...

That is the tach drive wire. Runs into the cab and ends up at the diagnostic port under the dash.