Dual altenators, good idea or waste ?

[96ccdd]

I'm changing my CUCV over to all 12v's. Are there benifits to running dual 12vdc altenators ? The CUCV used two to get the needed 24vdc but should I still run two ?

Thanks

[john8662]

Every CUCV that I've seen converted to 12V lost one of it's alternators. I don't think there is really a need for both.

[rdurh]

One alternator with 60+ amps should be OK for dual 12v batteries.

If you kept the second alternator you could convert it to an on board welder. Not too hard to do with a Delco SI alternator.

[JCalvin]

I like the idea of two that way you now for sure your getting enough juice as long as its not to much, though and the onboard welder is a good idea especially if you are planning on using it for a trail rig or service vehicle

[96ccdd]

This truck is being built for off-road use. Are there any articles about changing it to use as a welder ?

Thanks

[rdurh]

Try these links. I've done the conversion several times using Delco 15si and 17si welders. It does work and is a fairly easy install. The hardest part is coming up with a good mounting location. The biggest cost was the welding cable.

There are several options for an on-board welder. You can have straight DC welding, or as the article from Pirate4X4 shows you can go with AC welding. DC welding using a Delco SI alternator is the easiest from my experience.

http://www.geocities.com/damonfg/obweld.html
http://www.huv.com/jon/jeep/Welder/on-board-welder.html
http://www.trailhed.com/welding.html
http://www.pirate4x4.com/tech/on-boardwelder/index.html

[85-m1028]

the cucv delco alternators are 100 amp, you can run two but I think only one of them is ever doing the charging and the other is more like a back up. I think I read that somewhere in the Ross Common Equiptment guide to 12V conversion "that will give you instructions on all the conversions possible"

[moondoggie]

Good Day!

"...you can run two but I think only one of them is ever doing the charging and the other is more like a back up." I've always wondered about this subject. Two 12V alternators in parallel, unless they're almost impossibly well-matched or external control circuitry is involved, should work as you've said. If there's even the slightest difference in output voltage (& without the above, there certainly will be), the one with the higher output voltage will wind up producing most of the current, the degree being related to how different the output voltages are. In other words, the output voltage of the higher-output-voltage alternator will satisfy the lower-output-voltage's regulator, & it won't provide as much, if any, charging current.

If the vehicle required max current to maintain system voltage, say immediately after a normal start or for awhile after a long grind on the starter, then the current outputs should be more equalized.

If someone can let us know about alternator-matching and/or external control circuitry to equalize two alternator outputs, PLEASE let us know. For me it's simply technically interesting; for folks contemplating doing this, it would at the very least explain why one alternator shows more frequent electrical parts failure than the other.

Blessings!

[GMC Hauler]

Good Day!

"...you can run two but I think only one of them is ever doing the charging and the other is more like a back up." I've always wondered about this subject. Two 12V alternators in parallel, unless they're almost impossibly well-matched or external control circuitry is involved, should work as you've said. If there's even the slightest difference in output voltage (& without the above, there certainly will be), the one with the higher output voltage will wind up producing most of the current, the degree being related to how different the output voltages are. In other words, the output voltage of the higher-output-voltage alternator will satisfy the lower-output-voltage's regulator, & it won't provide as much, if any, charging current.

If the vehicle required max current to maintain system voltage, say immediately after a normal start or for awhile after a long grind on the starter, then the current outputs should be more equalized.

If someone can let us know about alternator-matching and/or external control circuitry to equalize two alternator outputs, PLEASE let us know. For me it's simply technically interesting; for folks contemplating doing this, it would at the very least explain why one alternator shows more frequent electrical parts failure than the other.

Blessings!
This is a good question. If you use the same brand alternators, you really need not worry about this. Most generators have something called "droop" either intentionally or unintentionally built into them (intentionally, as in control circuits as you described, unintentionally as the design characteristics, stator resistance, ect), alternators being no exception. Droop is the voltage amount that the generator output drops from no load to full load. As long as the droop amounts are closely matched, the alternators will pretty evenly share load. They will still share load with a somewhat mismatched droop characteristics, just not as evenly.

For example: at no load, your alternator voltage may read 14.1 volts, but at full load (100A assume), your alternator output voltage is 13.5. You have a droop of .6V over the range of the generator. You have seen this in your vehicles already. Think about it, when all the lights and loads were on in your vehicle, voltage was usually lower. That was the natural droop built in.

Assuming both generators (or alternators) have the same droop, assume that:

Alternator A: 100A @ 13.5
Alternator B: 0A @ 14.1

Now, per your very good description and the droop curves, this mismatch will cause alternator b to pick up load from alternator a until they share load within the parameters of the droop curves.

I have done the dual alternator mod. I have read current from both alternators and they are pretty well matched over the range of the alternators.

Subsequently, this is exactly how load is shared and shifted between power generation machines, in power plants and submarines alike.

[Ratau]

Sorry to hi-jack the topic but this is kind off related.

If one drive on off road trails you don't get to the rev's where the alternator deliver the amps needed the charge the batteries to full capacity. By starting and stopping a lot you take more out the batteries than what you put back and you end up with weak batteries after a few days.

I was reading about a modification to replace the voltage regulator with a unit that pushes up the voltage at low rev's and by doing this the current into the battery also increases.

Is such unites available in the USA or do you have any links for web-pages?

[moondoggie]

Good Day!

GMC Hauler: You're one of the reasons the Page is the best investment I've ever made. Thanks!

Blessings!

(signature in previous post)

[GMC Hauler]

Good Day!

GMC Hauler: You're one of the reasons the Page is the best investment I've ever made. Thanks!

Blessings!

(signature in previous post)
Thank you very much.

Don't discount yourself.... You frequently contribute and are more times than I can remember "the voice of reason".