Dual alternators, idea..

[1985_K5_Silverado]

If you think about it, an on-board air compressor (and an air tank) would be nifty. Not only for inflating tires, but running impact wrenches (talk about getting 6 or 8 lug nuts on and off in a hurry) and other air tools, inflating rubber rafts, and all kinds of applications.

 

[colbystephens]

i don't know about your engines, but i think there's enough space for me to run dual alternators, a/c and an air compressor off my 6.2. might be kind of a load tho.

 

[1985_K5_Silverado]

i don't know about your engines, but i think there's enough space for me to run dual alternators, a/c and an air compressor off my 6.2. might be kind of a load tho.

I see a supercharger in your future.

 

[colbystephens]

i don't know - was thinking turbo. that way i'll have room to run a dishwasher off of it if i extend the crank through the front grill so that when i'm out on the trail bbq'ing, i don't have to do dishes.

 

[Blue85]

Not to hijack the A/C thread, but you can't really run two alternators in parallel. The stronger one will carry the load every time.

Oh no! You just proved that my system doesn't work. Maybe my truck still starts because it doesn't know any better?

Let me tell you how it actually works. There is load sharing. Of course it is not even, but why does this matter? At lower loads one will deliver more current than the other. As the load increases, the voltage will drop until both alternators are at maximum output. One will probably last longer than the other, but even the one carrying more load will still last longer than if it was running as a single. You will run two stock alts of the same style, so they will have similar characteristics, which helps them to share.

Here are the advantages over a single high-output alternator:
1) cheaper. You already have one and the second should be less than $50 with cables and some junkyard brackets. Have you priced high-output units?
2) More current at idle. You don't get 140A from the high-po unless you rev the engine way up. Some high-pos actually deliver less current at idle than a stock one. Running two clearly doubles your idle current capacity (which is usually the limiting factor that makes you want to upgrade to begin with).
3) Reliability: Aftermarket alternators can be finnicky. Even if you lose one stock one, you can still drive. You just can winch as much or run as many accessories. Then you can pick up a replacement at ANY parts store (or junkyard) instead of special ordering. In fact, you will be able to get a new one for free from the lifetime warranty (this reinforces #1). Reliability is enhanced even more if you set the two up on seperate belts.

The only drawback is that it consumes more space underhood.

 

[readymix]

I need pics of that Blue85. I have been thinking about dropping one in where the stock air pump is for a long time.

 

[Blue85]

I guess those pictures were lost in the CK5 server crash a while back. I will have to get them off my other computer sometime (although in reality I will probably forget this for a long time).

It seems to me I modified the stock A.I.R. brackets and got it to work. I did two setups. The first put the second alternator further forward so that it ran off the old A.I.R. belt. That is nice to have two seperate belts, but that crank pulley is smaller than the other two, so the second alternator runs slower. In the second setup, both alts run off the same belt. If I could ever find a water pump pulley with three pulleys of equal diameter, that would be the best setup, IMO. I think you could drive with any one of the three belts broken then, but I would have to look at it.

I'm sure I posted on it before, but of course the pictures won't show up.

 

[NYDIESELDAVE]

You could also get a driver side alt brkt off a cucv 6.2 diesel and see if that will work out. I have one if you need.

 

[78Suburban]

Oh no! You just proved that my system doesn't work. Maybe my truck still starts because it doesn't know any better?

Let me tell you how it actually works. There is load sharing. Of course it is not even, but why does this matter? At lower loads one will deliver more current than the other. As the load increases, the voltage will drop until both alternators are at maximum output. One will probably last longer than the other, but even the one carrying more load will still last longer than if it was running as a single. You will run two stock alts of the same style, so they will have similar characteristics, which helps them to share.

Here are the advantages over a single high-output alternator:
1) cheaper. You already have one and the second should be less than $50 with cables and some junkyard brackets. Have you priced high-output units?
2) More current at idle. You don't get 140A from the high-po unless you rev the engine way up. Some high-pos actually deliver less current at idle than a stock one. Running two clearly doubles your idle current capacity (which is usually the limiting factor that makes you want to upgrade to begin with).
3) Reliability: Aftermarket alternators can be finnicky. Even if you lose one stock one, you can still drive. You just can winch as much or run as many accessories. Then you can pick up a replacement at ANY parts store (or junkyard) instead of special ordering. In fact, you will be able to get a new one for free from the lifetime warranty (this reinforces #1). Reliability is enhanced even more if you set the two up on seperate belts.

The only drawback is that it consumes more space underhood.

I happen to have a second stock gm alt laying around. I also an old powermaster 100 amp 1 wire alt laying around.. Which would I be better off running in conjunction with my stock alternator? If I use the powermaster, wiring will be easy... What if I use the stock alternator as my second alt? What do I run the wires to? I think I have a spare wrining harness laying around, so I could steal the plug off of it, but what would I wire all that into?
thanks,
James

 

[diesel4me]

Factory equipped!...

Many Ambulances came factory with dual alternators..my brother had a
78 K30 he bought from his towns fire dept. at auction many years ago..had a 400 SB,TH400/NP203, Dana 60 front,and dual rears!..it was a "Rescue Wagon",the truck they carried the Jaws of Life in,generators,etc..many conventional Ambulances had them too..

It would not be too hard to rig up alternator brackets from an older motor that had them on the drivers side..or use one of those "low mount" alternator brackets they use on hot rods in addition to the stock passenger side mounts..you could use a plow pump pulley off the crank,or water pump to power the second alternator...

I never looked closely at the dual alternator setups wiring,but I'm betting all they did was add two more wires to the alternator plug and ran them over to the other ones plug,and ran another 8 ga wire to the junction block,or positive battery cable of the second battery (his truck had dual batteries too)..

 

[78Suburban]

The Wiring

The wiring is definitely what intimidates me. If I knew how to wire it up, I would be very tempted to use this setup. I'm going to bring my alt and battery into Advanced today and see if they are both still good. I knew my battery was about to go, but I hope I didn't kill the alternator with mud.. I wish I could think of some kinda mud shield for the alternator
thanks,
James

 

[sebban]

I'm going for the setup where you keep the stock system original, and add an extra battery and run the second alternator as a separate system. If your battery or generator fails, it´s easy to swap to the other one. You just switch the batteries or the cables... And at the camp I can run lights, music, computers, refrigirator, whatever, if i kill the battery I can still start in the morning... Or if you get stuck and use the winch, you won´t kill your engine when the battery is dead..

I'm no expert on electrics maybe I missed something, but I only see advantages in runing two systems?!?

 

[Jagged]

If you wanted to get real fancy you could have some bus-tie switches in the cab connected to some relays so there's no cable swapping.

Two independent circuits except when one fails, you flip the bus-tie switch and one battery/alt is isolated, running both systems off one.

 

[colbystephens]

see, now that's why i have a subsription to ck5.

 

[Blue85]

The wiring is definitely what intimidates me.

It's very easy. Just wire them in parallel. Use a ring terminal to ring terminal cable between the two and then wire the two small connectors together as well.

It's harder to set up two seperate systems, but even then all you really need is an isolator or switch.


One note on the CUCV alternator brackets. I think those were 24V systems, so one of the alternators was probably isolated from chassis in order to run them in series. No big deal, though, you just need a ground wire to it or remove whatever was used to give the isolation.

 

[colbystephens]

kind of going back a few posts, but if you run out of space to mount the bracket directly to your engine, it seems to me you could always make a bracket that mounted to your frame rails.

 

[ryoken]

kind of going back a few posts, but if you run out of space to mount the bracket directly to your engine, it seems to me you could always make a bracket that mounted to your frame rails.

not unless your running solid motor mounts... even then i wouldn't do it, motors move, frames twist, that belt wouldn't stand a chance....

i wouldn't mind a second alt, but i think my reason would be onboard welding. definitely could come up with a serious system with one dedicated to that.. i'm as psyched on getting welding capability as i am on getting air..

i wonder how crazy a fit all that would be... 2 alternators, power steering, york, ac, and smog... that's alot of pulleys! you'd really have to plan that out... i'd love to see a pic of it...

 

[colbystephens]

interesting. i didn't think of that.

 

[ryoken]

interesting. i didn't think of that.

don't get me wrong, i'm sure its been done.. matter of fact i seem to remember seeing it on something... iirc, i think the hauling mule at the marina had a setup like that.. just pointing out the reasons why i think its a bad idea....

i'm liking the idea of a dedicated welding/winching alternator...

 

[colbystephens]

i'm liking the idea of a dedicated welding/winching alternator...

agreed.

regarding the mounting - seems to me it would be cool if there were a set up where you had an engine with nothing on it, then having a single plate made which would bolt up to all of the locations where engine accessories are usually mounted, then attatching the accessories to the ends of this plate which would be made in such a way that the accessories would be adjustable in placement so you could really fit alot of acessories on it. i mean, this could make virtually the width of your engine compartment the limit.