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one Alternator or two? if you had the choice.

mk153smaw

NAXJA Forum User
Location
Fort Lee, Va
Ok I am now at the point where in the last thread I had removed my A/C condensor and the mechanical cooling fan completely. I modified a Alt to fit where the A/C used to go.
My question is this, I could just not remove the old alt (leaving it where it is) and install the modified mount and 2nd Alt having a dual system.
or would this just over complicate my engine bay negating any positives the added Alt would give me?
I am thinking if I added it I could run the core eletrical from the "upper" Alt and then leave all the non running accessories to be serviced by the "lower" Atl (which if it dies from being fouled by mud, who cares?)

Hmm, what do y'all think?
 
What year model Heep? What kind of original alt and what kind of secondary alt?? early stuff used a self contained alt (delco) and late model stuff uses an externally regulated alt where the ecu does the regulation duties...if its the late type, the ecu might not like trying to regulate two alts.

Good idea in general though...but personally I won't give up my A/C it gets hot and steamy with the windows up in the mud pit!
 
It is all from an '88. I dont need the A/c since I usualy dont have doors. I only put them on for the winter, it gets a little too bitter with cold and rain! ;) Both are Delco Alts
 
vetteboy said:
Make one into an onboard welder.

That would be cool ;) How do I do that?
 
No reason you couldn't run dual alternators.

You don't really have to "match" them - but if you're OBD (1991-up,) you'll want to either use the lower alt for primary duty, or use an ND up top and shift the PCM regulator to it - or you'll get a code.

You can use a Delco one-wire for the secondary alternator, or use an ND or something similar. If you use a unit that is not internally regulated, you'll need to add a regulator for it - Prestolite makes a decent unit that is usually used for marine applications, so it's pretty tough. If you can't track it down locally, give Rod a call and he can scare them up for you easily (link in sig, go to "San Jose Generator" and talk to Rod directly.) The secondary alternator can then be used to drive a secondary electrical system - compleat with a bank of deep cycle batteries - without any real difficulty. Ford does something like that on their late-model ambulances (130A primary and 160A secondary, I think. I'd have to check.)

The secondary alternator may also be used with a 'switched' regulator (turn the reg sense lead on and off, effectively putting the alternator on a switch) if you have an external regulator or access to the regulator "sense" lead. No need for batteries here - you just turn it on when you need it, and off when you don't. N.B. If you do this, you'll only have the secondary electrical system when the engine is running!

This would be the most effective way to isolate secondary batteries, it's just more work than most people are willing to put into the job.
 
Cool, thanks! I have a lot of time and plenty of spare parts lying around to play with, so this is all costing me nothing to fiddle around.
I do like the switched idea, that makes the best option I think.
 
mk153smaw said:
Cool, thanks! I have a lot of time and plenty of spare parts lying around to play with, so this is all costing me nothing to fiddle around.
I do like the switched idea, that makes the best option I think.

It would be easier, then, to use an externally-regulated alternator, since that gives better access to the regulator wiring. You can probably do something similar with a Delco CS or SI series, but you won't have as much access to the thing.

I don't recall, exactly, whether you should break the regulator sense lead or the field output circuit (provides power to the field windings,) but I'm sure it can be checked easily.
 
I left a note for myself for tomorrow after i finish up the install on the system. All the mod'd parts are still rough looking and I want to clean up all the bad cuts and paint the new parts so it looks factory'ish.
I will go thru my wiring diagrams and se what wires i have to fiddle with and what kind of harnes I am going to make.
 
mgreen84 said:
one suggestion....forget dual alts. go procharger!!!

Costs money.... I am saving for my roll cage right now.
 
lol...wow a serious answer..I'm just a broke redneck..wish I had money for hell ......even new tires
 
hehe, I had the guy at Autozone reccomend the same thing earlier this evening. I looked at him, then at my Jeep, then back at my empty wallet.
I wonder what it would be like with a charger on it?
 
needsrepair said:
Why 2 alt.

It largely depends on what you need the extra power for, and how much you need. As I said, it's fairly common on ambulances - but their electrical requirements are (relatively) phenomenal (as far as vehicles go.)

I've also seen it done on "radio trucks" for the fire department - it's less common, but I've seen it on their "command" trucks - where they've got to run several radio sets and assorted major electronics (computers and suchlike.)

Why do it? Because it gives you a separate electrical system to run the engine and to run accessories - which can be helpful with some electronics. Computer systems can be sensitive to such things.

It also afford a fairly low-buck way to break the "200A barrier" - it seems that the highest capacity I've seen in automotive alternators - save units by Leece-Neville and such - is 200A. If you need more, a second alternator can be the way to go.

Is it a mod for everyone? Hardly. Can it be done? Certainly. Can you do it? Probably - if you have the parts and materials for experimentation handy (the best place would be to fit it in place of the A/C compressor, methinks. A CS-130 with an offset ear - like the one used on RENIX - would probably be easiest. More adaptation is required if you use "straight" mounting, where the mounting ears are 180* apart. Mounting at 12:00 and 4:00 would probably be better. Considering the location, a relatively small case would probably also be better - a CS-130 would probably be pushing it (while a CS-121, while rather more rare, would fit better.)

I'd be interested in seeing your notes on the project once you've finished it.
 
Update to the project.

Ok got all the parts nice and smooth, painted and factory looking (which I like).
I have a convuluted relay setup that looks gross but works perfectly as envisioned.
One relay set lets me knoe that the primary system is good and running.
One set tells me the charge is going to the secondary battery keeping it at charge.
One set also lets me know that the second system is healthy and powering accessories non vital to engine function.
Here comes the cool part...
If the primary power fails the system senses the power loss routes Battery 2 to run the engine until a capacitor which is fed by system 2 is ready and triggers switch of power to be run by system 2. This protects against a spike from swapping systems. When the switch occurs the accessoires switch to running off Battery 1 and I can select what gets power and what to shut off. A trickle lead is setup to make sure Battery 1 is maintained during the process.
I am making a LED board for indicators with green, yellow, and red for obvious reasons of good or bad.
The computer always gets power from both systems but whichever is primary the secondary feeds another capacitor which just lets a trickle thru to avoid the momentary outage during relay drops.

I am making a service board in a box to house a much smaller version, which I will mount on the ceiling with the rest of the electronics.
 
BTW I have a professional certificate of Electrical Engineering from Arizona State University.... That makes me just knowlegable enough to be dangerous without supervision!:gee:
 
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