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Lets talk dual altenators again.

the sheave from my old 10si alt on my 77 is very small
I just put a 12si (smoothed and painted it gloss black) in and the pulley on it is huge in comparison
when I get a chance I am going to stuff the old sheave on the new 12si alt
 
I've only seen dual altenators on ambulances and fire rescue trucks.They are probably the only vehicles that really need them--GM put 2 large batteries with a single altenator in all the diesel trucks,and they dont have too many problems.
I can see if you have more lights,big amps,stereo,winch,and other accecories that draw heavy loads you need the extra amps to run them,but I was always taught altenators are not battery chargers--they are battery maintainers--all manufacturers warn against using altenators to charge a dead battery,supposedly its harmful to it and can shorten its life.Using an alternator to run all the accesories does much the same thing. I would say it would be better to have dual batteries,or one large one like a semi truck with more cranking amps and reserve capacity,lots of plates in it--most of the big rigs with one or more huge batteries have a single delco altenator,bigger than ours,but not much more amperage as far as rated output.The battery(s)would then handle most of the load,and the altenator will merely maintain the battery charge,rather than be carrying the entire burden of the vehicles electrical system.
I think 2 altenators would still only put out the same rated amperage paired up as a single one--maybe I'm wrong,but to me its like putting a tee fitting on a pipe--the water will flow out each side equally--each altenator would be working half as hard,but you'd still max out at 78 amps,or whatever they are stamped on the case--I dont think you would get double the amperage .If I'm wrong,someone explain why--inquring minds want to know!. /forums/images/graemlins/confused.gif /forums/images/graemlins/screwy.gif
 
Sorry diesel4me..but...

1. Almost all smei trucks have 4 batteries, a very slim amount only have 3.
2. Most of the truck alts are 140 ampers but they are HUGE, all the parts are much larger than say a GM 140 amper because the commercial alt. is designed to run at full load most of the time.

3. Dual batteries would help and probably do the trick as far as giving me enough amperage at the MOMENT to run my stereo at full power and the alt. would catch up when it's off but like you said, thats hard on the batteries and the alt itself.

4. I disagree that you will only get the amperage from one alt. My 100 amper combined with a 78 amper would obviously be 178 amps total and I think I could get all of that if everything is wired correctly.

As far as just running dual batteries, I am picky and wnat to be able to leave my stereo on continually and the charging system be able to handle it. If I don't have enough amperage feeding the dual batteries to keep up the stereo than I will eventually have two dead batteries. Correct? It's like pouring gas into a tank with a hole in it, if the hole is flowing the gas out faster than your pouring it in than you aren't getting anywhere right? /forums/images/graemlins/screwy.gif

There is the obvious way to do it which is to get a second battery and have it soley connected to just the stereo hot and have one altenator wired directly to that stereo battery keeping that hole system completely isolated from the trucks wiring, A/C, fans, lights, and ignition.

I would prefer to make both alts. feed both batteries though because I do a lot of jumping other equipment around my ranch and also if one alt. fails the second one can get me home with everything off.

BTW, I have a strike capaciter wired in with my amps if that matters. /forums/images/graemlins/dunno.gif
 
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Sorry diesel4me..but...

1. Almost all smei trucks have 4 batteries, a very slim amount only have 3.


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WRONG. Most newer semis have 3 12v batteries. Most older semis had 4 6v batteries wired in paralel/ series, = to 2 large 12v batteries.
 
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Sorry diesel4me..but...

1. Almost all smei trucks have 4 batteries, a very slim amount only have 3.


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WRONG. Most newer semis have 3 12v batteries. Most older semis had 4 6v batteries wired in paralel/ series, = to 2 large 12v batteries.

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Sorry to dissapoint you but I'm right. we own 14 trucks and I do a majority of the mechanical work. I know trucks. I DON'T know what is in anything post 1998 since we own mostly early to late 90's models but I doubt they have less than 4 batteries. We only have 2 trucks out of 14 with 3 batteries and they are all 12V.
 
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Sorry diesel4me..but...

1. Almost all smei trucks have 4 batteries, a very slim amount only have 3.


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WRONG. Most newer semis have 3 12v batteries. Most older semis had 4 6v batteries wired in paralel/ series, = to 2 large 12v batteries.

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Sorry to dissapoint you but I'm right. we own 14 trucks and I do a majority of the mechanical work. I know trucks. I DON'T know what is in anything post 1998 since we own mostly early to late 90's models but I doubt they have less than 4 batteries. We only have 2 trucks out of 14 with 3 batteries and they are all 12V.

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So you've seen 12 out of 14 trucks that have 4 batteries. I've been driving Class 8 trucks for over 27 years. Pre '80 most trucks came with 4 6v batteries in pairs wired in series then those pairs wired in parallel. Since then most have had 3 12v batteries wired in parallel. In the last 27 years I've pretriped over 300 trucks and most were of one or the other as I listed above. From what I've seen 4 12v batteries are rare in class 8 trucks.
In fact when I looked into installing a extra battery in my '88 Pete I found that the hold down for 4 batteries in a 37X series Peterbuilt was special order only.
 
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Sorry diesel4me..but...

1. Almost all smei trucks have 4 batteries, a very slim amount only have 3.


[/ QUOTE ]

WRONG. Most newer semis have 3 12v batteries. Most older semis had 4 6v batteries wired in paralel/ series, = to 2 large 12v batteries.

[/ QUOTE ]
Sorry to dissapoint you but I'm right. we own 14 trucks and I do a majority of the mechanical work. I know trucks. I DON'T know what is in anything post 1998 since we own mostly early to late 90's models but I doubt they have less than 4 batteries. We only have 2 trucks out of 14 with 3 batteries and they are all 12V.

[/ QUOTE ]

So you've seen 12 out of 14 trucks that have 4 batteries. I've been driving Class 8 trucks for over 27 years. Pre '80 most trucks came with 4 6v batteries in pairs wired in series then those pairs wired in parallel. Since then most have had 3 12v batteries wired in parallel. In the last 27 years I've pretriped over 300 trucks and most were of one or the other as I listed above. From what I've seen 4 12v batteries are rare in class 8 trucks.
In fact when I looked into installing a extra battery in my '88 Pete I found that the hold down for 4 batteries in a 37X series Peterbuilt was special order only.

[/ QUOTE ] Well, don't know what to tell you, 27 years is a long time but I made a quick call to my parts man down town and asked if the batteries I usually order are 12v or 6v. He says he doesn't even carry large 6v batteries anymore because they got phased out. All of our 4 battery trucks have 12V batteries. He said the older trucks were wired with 6v batteries and thats basically gone. I don't have any trucks older than '88 anymore. BTW, our '92 Pete has 4 batteries, all 12V. /forums/images/graemlins/waytogo.gif
 
why are you quoting a quote of a quote of a quote?
 
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why are you quoting a quote of a quote of a quote?

[/ QUOTE ]Don't worry about it, it doesn't concern you.
 
no worries here
I will decide what concerns me
 
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no worries here
I will decide what concerns me

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Good, this isn't something that would.
 
Any chance you can do a before/after voltage test at idle on the alternator?

If you get a goodly amount, I may have to look around and see if there is an OD pulley for the 5(?) groove serpentine setup.
 
Somewhere I recall reading that peak alternator output is in the range of 5 thousand to 9 thousand alt rpm. Limit max alt rpm to 12 thousand at engine redline.

Not sure that it's correct, but to me a "sheave" implies ropes or cables wound around it, not a belt.
 
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why are you quoting a quote of a quote of a quote?

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Why are you being an ass? /forums/images/graemlins/rotfl.gif /forums/images/graemlins/histerical.gif /forums/images/graemlins/histerical.gif
 
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BTW, I have a strike capaciter wired in with my amps if that matters. /forums/images/graemlins/dunno.gif

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Good thing i read through the majority of this thread before posting..
I was gonna say you need a capacitor if your headlights are dimming and your batt voltage is dropping when your stereo hits hard..
Is it a .5 or a 1 ferad capacitor you got?? How many peak watts total?

/forums/images/graemlins/dunno.gif
 
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Autozone. Ask for an alternator for a 1995 Pontiac Transport with a 3.8 and rear air.

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Tried it, doesn't work.

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az-k5 is running an alternator out of a Pontiac Transport with AC. It was a pretty easy swap and supplied alot more power then the stocker. It required a special pigtail be wired in but his works great. /forums/images/graemlins/dunno.gif

Harley
 
Hmmm---so if I hook all my spare altenators together it keeps getting more and more amps--if I put 10 37 amp altenators together I will get 370 amps??? /forums/images/graemlins/confused.gif--I can see if I hooked them in series I'd get 120 volts,but in paralell they would still put out 12 volts,but at 370 amps?? /forums/images/graemlins/confused.gif /forums/images/graemlins/thinking.gif
I know the semi trucks use several batteries--the point I was making was the physical size of the battery,and the number of plates in it--bigger===more cranking amps and reserve capacity--the semi's altenator is bigger to help it run cooler in my opinion,it probably doesnt use all 140 amps constantly,only when all the lights and accesories are on. Maybe we should just get one of those delco giants off a kenworth and adapt it to our trucks!--between that altenator and just one of those big batteries,it would be hard to kill. /forums/images/graemlins/crazy.gif
 
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Tried it, doesn't work.


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Have one, it works. What didn't work for you. It is a bit bigger to fit, but my bracket is left alone with no mods. It was a special order and a little convincing to get them to sell it to me. The Pontiac one uses a 3 wire plug, the extra wire is for the computer I think. I bypassed it and spliced in just the two wires onto a 3 wire ($5) potiac pigtail that autozone had. I have had it for nearly a year now and love it. Use the smallest pulley you can find to overdrive the alternator if it gives you any idle issues. My stock one is fine. At around 800-900 RPM they put out more than the stock one at max.
 
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Use the smallest pulley you can find to overdrive the alternator if it gives you any idle issues.

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SHouldnt you use the largest you can find to overdrive? And a smaller one to underdrive?
 
Nope. A smaller pulley will spin it faster. Just like a lower numbered gear ratio will spin your tires faster in 1st gear.
 
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