Dual Alternators?

[KDMatt]

Hrm ... so I just got done installing an electric fan (fan clutch, after less than 20k miles ... but over the course of 4 years ... stopped working right... ) and while I am quite pleased with it's cooling capacity, I'm now concerned about my charging system ... at least while at idle... The fan, draws somewhere in the neighborhood of 14 or 15 amps, which, on my stock 50 amp alt is pretty significant.

The obvious solution is to spend the blood sweat and tears (not to mention do-re-mi) of splicing in an externally regulated badboy from another car ... but I have another idea ... and this is strictly a feeler to see what the electrical gurus on these forums think.

The stock, externally regulated alternator is only $39.99 from O'Reilly's ... and the A/C in my car hasn't been hooked up in decades... I think you can see where this is going...

Has anyone ever, instead of upgrading a single alternator, deleted their A/C entirely, and just added a second one?

I have to imagine if one solders in a diode in the right place, and then splices the wires of the second one into the first one (in parallel, naturally), it would work quite well... but then again, I'm no expert, so I'm turning to you guys.

I obviously won't attempt this if it's dangerous or something (don't want to fry my voltage regulator .. even though that's practically brand new too)... But, If it's possible, that means that I could achieve a theoretical 100 amps ... minus A/C ...

So, thoughts? I'm honestly just curious, and I can't find any other threads on this idea ... just wondering if maybe that's for a reason! :stupid:

[Gary in NJ]

In my opinion, it would be more practicable to increase the output of a single alternator. A dual alternator only really makes sense when redundant operation is necessary, like on an aircraft.

The bigger question is "why do you need so much cooling capacity?".

[hogie]

If you need that much current just put on a single wire gm alternator. They crank out a ton more and there is a bunch on posts on hybridz saying how to do it.

The mods are pretty simple looking. Had the 280zx alternator not been so cheap and easy that is the route i would've taken.

[S30Driver]

It is an interesting & unique idea, but in the end, I don't think the hassle of fabrication & wiring is worth it. I agree, the zx, gm alt, or even the zspecialties 105amp alt are the way to go, plus they eliminate the external regulator.

Does the fan have a thermostat switch that turns it on & off at the proper range?

[Z train]

I don't see how you think using 1/3 of your alternators capacity is"significant".Change the pulley* so the unit puts out more amps down "low"(idling & cruising).Or upgrade to a ZX unit with the same pulley.

* any rebuild shop will have them

[KDMatt]

I don't see how you think using 1/3 of your alternators capacity is"significant".Change the pulley* so the unit puts out more amps down "low"(idling & cruising).Or upgrade to a ZX unit with the same pulley.

It's not a big deal during the daytime ... or when it's sunny out..

but imagine it's raining, and I need my wipers, my headlights, the electric fan, and I'm sitting, signalling (with brakelights and turn signals, possibly rear defogger ) ... that would pretty much use up almost all of the amperage, guaranteed.

Gary, it's not so much about 'needing' the 'cooling capacity' as it is about practicality. The stock, mechanical fan clutch was something I replaced a few years ago (with an OEM unit from MSA), and it worked flawlessly until Saturday night, I was stuck in a traffic jam, and the engine started getting a bit hotter than I would have liked (215 ish degrees, past the M on TEMP) ... it's a point where historically the clutch would lock and let the fan spin faster, but it wasn't happening.

Ultimately I decided that it was wiser to invest in an electric fan, as I wouldn't have to worry about the clutch for it going bad ever again.

... and incidentally, S30Driver, it is on a thermostat, I wouldn't trust myself to switch it on a toggle, 'felt like it was better to have it rigged to go automatically.

Hogie, gonna look into the GM alternator. Thanks for the tip!

Also, I still don't have the positive switched current for my relay (yep, wired in a relay, did this properly) wired in yet. Can anyone recommend a good place under the hood to splice it in? Right now it's just running off the main positive lead, which means the fan keeps spinning after I pull the key out (for an extra 4 minutes or so ... just 'til the engine cools down ), and I'd like to change that.

[Gary in NJ]

Gary, it's not so much about 'needing' the 'cooling capacity' as it is about practicality. The stock, mechanical fan clutch was something I replaced a few years ago (with an OEM unit from MSA), and it worked flawlessly until Saturday night, I was stuck in a traffic jam, and the engine started getting a bit hotter than I would have liked (215 ish degrees, past the M on TEMP) ... it's a point where historically the clutch would lock and let the fan spin faster, but it wasn't happening.

From the perspective of a system designer; you are going from a mechanical system with two failure modes (fan clutch & fan belt), to an electrical system with many failure modes (fan belt, thermoswitch, fan motor, wiring harness, connectors, alternator, regulator, to name a few).

I'd keep it simple. The OEM system works well for the vast majority of the cars.

[oldhemi]

Since your A/C is not hooked up, have you removed your condenser?

I have found that the "rebuilt" units these days NEED a lifetime warranty because they fail a lot. Used to be a 30 day warranty was good enough.

I have been fortunate in Connecticut and here in Houston to have excellent electric component rebuild shops. Prices were not much more than the auto parts places and in some cases offered a amperage output modification.

Three observations on the internally regulated alternators:

1. The regulator seems to be the part that fails on rebuilds.

2. Getting rid of the external regulator helps clean up the engine bay.

3. You *might* have a problem with the tach depending on the alternator you choose. Hybridz and this site has some discussions.

[KDMatt]

From the perspective of a system designer; you are going from a mechanical system with two failure modes (fan clutch & fan belt), to an electrical system with many failure modes (fan belt, thermoswitch, fan motor, wiring harness, connectors, alternator, regulator, to name a few).

I'd keep it simple. The OEM system works well for the vast majority of the cars.

Again, I guess diff'rent strokes for diff'rent folks. I've heard other people swear by the electric fan upgrade. Moves more air and frees up some torque/hp.

The stock cooling system is indeed quite sufficient ... until a component breaks or fails (which is what happened here) ... the advantage of the setup I've installed is that all of the replacement parts I could ever need for it are available off the shelf. I DD my Z, and waiting a day or two for replacement stuff to come-in can often times be quite obnoxious.

Doing an alternator upgrade has been on my to-do list for a while anyway, so I don't feel too remiss. The purpose of this thread isn't necessarily to debate whether or not swapping fans was a good idea... it was more to discuss the best ways to provide more amperage to my (now) sub-par electrical system... with the initial purpose of examing the possibility of a dual alernator setup.

oldhemi ... I was honestly going to try and go to a boneyard to pull something ... I hear there's a Maxima alternator that works exceptionally well.

The ZX is only in the 60/70 amp range IIRC ... whereas some of the late/mid 80's maximas are 85 or 90.

[MikeW]

The bigger question is "why do you need so much cooling capacity?".

In Minnesota

[KDMatt]

In Minnesota

Well as I'm sure you know relative humidity has little to do with engine temperature ... and even though there's not as much oceanic moisture up here... we do regularly have a few months in summer between 80 and 90 degrees... with a few past 100 ...

Better safe than sorry IMO.

Oh, and we have indoor plumbing here too...

.. and skyscrapers

[MikeW]

I'm just kidding. My co-worker in Minnesota has explained how you have to sometimes shovel a foot of snow off of your car in order to begin work on the 1 inch layer of ice beneath that. I realize that it can get plenty hot there in the summer.

All time high in Minnesota: 114 degrees F

All time high in Georgia: 112 degrees F

http://en.wikipedia.org/wiki/U.S._state_temperature_extremes