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In my van I spin two alternators. One for the vehicle (stock) and one for the toys (200 amp).
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My van is a 1988 Chevy Astro. 4.3L V6 Engine.
I removed all of the Air Conditioning components which created a perfect spot for a second alternator.
The aftermarket alternator is the same shell as a stock alternator but it is pushing out 200 amps. (supposedly)
It mounts up fairly easily with only a little modification to the left side. This could probably be done differently but this is how I chose to do it.
I welded on a small metal tab for the left side to bolt up to.
The tab I added is shown in Color for emphasis.
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I used the existing A/C bolt to mount the right side of the alternator by throwing in a spacer on the backside to keep it from moving forward and back.
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Left=200 amp. Right=Stock.
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Piece of cake, right?
The 200 amp alternator was purchased from DB Electrical on Ebay. If I ever find my receipt I'll provide more details such as a URL, price, etc.
 

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thanks for the great post but my ? is, how did you do the wireing so that both would kick on and work togather.

thanks
 

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Nice post.

I have a hard time to find information about how to plug the two alternators in my truck.

I will like to know how did you finally plug the two alternator and if you used some kind of relay or basically plug them both into the positive circuit of the battery. Or if they are in two different circuit.

My project is to add an alternator and a battery. Why I want to add an alternator instead that using a high amp one; it is because the normal alternators are hundred dollars (cheap) and life time guaranty. Instead that two hundred seventy for a high amp with one year guaranty. (And some other reason…)

I have a 1990 S10 4.3L in a ElCamino 1984.
 

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Discussion Starter · #4 ·
I'll answer this question the best I can. I'm not an expert by any means and I would hate to have people toasting and frying their electrical components because of something read from me.

Okay, disclaimer aside, more power is always a good thing. vipaire, in your case what you are wanting is more power for less money. I don't believe you are going to get it with the way you described. People believe that if they have a 105 amp alternator and they want more power they should go buy another 105 amp alternator. It is my understanding that this does not increase your power unless you run another battery.

Unless you have sufficient battery capacity to dedicate to the electrical demands, and use the correct type of battery, simply adding more alternators WILL NOT solve your power problems.

In the early days, cars used generators rather than alternators to power the vehicle's electrical system and charge the battery. That's not the case anymore. Alternators are not generators. Alternators maintain a stream of energy to supply the vehicle s electrical demands. Adding second alternator will not produce HIGHER power. It will, however, add more available power which you could use with a second battery.

As your electrical components use up power from your battery, it is replaced by your alternator. Adding a second alternator would do nothing more than speed up the rate which the alternators replaces this power in your battery.

105a + 105a does not equal 210a.
105a + 105a = lots of 105a

I run 2 alternators and 2 batteries in my van. Each alternator directly connected to each battery. One for the van, one for the toys (audio system, electric compressors, lights, etc.)

If someone who actually knows what they are talking about wants to chime in, feel free to.
 

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Wow that a nice quality answer. Thank a lot for that.

So basically I should try to add a battery first and then see if my alternator keeps on charging them. If not then I should think about a higher output alternator or a dual alternator.

What I want to run is a 700w invertor…

Question? Is your second battery ground to the car body?
 

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Discussion Starter · #6 ·
You're welcome. If you are going to run two batteries off of one alternator I would suggest a Battery Isolator. A battery isolator allows you to maintain 2 batteries from a single alternator, keeping the starting battery isolated from the 2nd battery.

vipaire said:
Question? Is your second battery ground to the car body?
No, it is not. Although I'm not sure that it would matter if it was. As long as the ground post from the battery I want to draw power from is connected to the chassis metal it would be okay.

In other words don't try to hook up the positive side of your inverter to battery #2 and then the ground to the chassis metal but neglect to hook up the negative post of battery #2 to the chassis metal. That would be like your inverter trying to pull positive from your battery #2 and pulling your negative from battery #1. Ya know?

Rule of thumb: If you're going to run 2 alternators and 2 batteries... keep them seperate systems. Try to connect your 2nd battery directly to the load and nothing else. There are ways of configuring them into one large system but mixing them up can get very expensive and also has a greater chance of becoming catastrophic. :eek:
 

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Discussion Starter · #9 ·
Yes, that is exactly how mine is set up. Two totally separate systems.

It is my understanding that grounding on the vehicles metal body would not cause a problem. This would work fine because you are just using the metal body of the chassis to conduct electricity. Only one of the polarities are used so the circuit is not complete and would not cause a conflict with the other system. What I mean is you could do it like this....
 

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AstroAustin said:
I'll answer this question the best I can. I'm not an expert by any means and I would hate to have people toasting and frying their electrical components because of something read from me.

Okay, disclaimer aside, more power is always a good thing. vipaire, in your case what you are wanting is more power for less money. I don't believe you are going to get it with the way you described. People believe that if they have a 105 amp alternator and they want more power they should go buy another 105 amp alternator. It is my understanding that this does not increase your power unless you run another battery.

Unless you have sufficient battery capacity to dedicate to the electrical demands, and use the correct type of battery, simply adding more alternators WILL NOT solve your power problems.

In the early days, cars used generators rather than alternators to power the vehicle's electrical system and charge the battery. That's not the case anymore. Alternators are not generators. Alternators maintain a stream of energy to supply the vehicle s electrical demands. Adding second alternator will not produce HIGHER power. It will, however, add more available power which you could use with a second battery.

As your electrical components use up power from your battery, it is replaced by your alternator. Adding a second alternator would do nothing more than speed up the rate which the alternators replaces this power in your battery.

105a + 105a does not equal 210a.
105a + 105a = lots of 105a

I run 2 alternators and 2 batteries in my van. Each alternator directly connected to each battery. One for the van, one for the toys (audio system, electric compressors, lights, etc.)

If someone who actually knows what they are talking about wants to chime in, feel free to.
Well done, that covers it. But just my .02 here, you don't have to worry about keeping the #1 and #2 battery circuits seperate. As long as the batteries and alternators are wired in a parallel circuit (and not a series circuit) you will be fine. You will have a 12 volt system, just with a lot more reserve. Wiring the batteries in series would give you a 24 volt setup and fry everything in the car.

I will be adding another battery to my van soon, but not another alternator. Although it is a neat idea.
 

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You really couldnt do a series circuit on the alternator as the ground is through the housing, I would not recomend hooking both outputs together without some kind of isolation circuit as the regulated voltages could be slightly different and feed back isnt good, not saying it wouldnt work, but I would keep 2 circuits. 105+105=210A of charge capability, you would want to upgrade your battery in that case, possibly a 1000 amp battery. I would run 2 batteries on separate circuits to prevent issues with current draws and voltage sag to the ignition and ECM tho. Make sure if you are running high powered car audio to either have a large cap with the amp, or mount the 2nd battery close by the amp for high current draws that occur when the bass hits hard.

Side note, 2 batteries have 2x the connection surface area for better current transfer.
Some Diesels will run series for 24v 1/2Amps, some will run parallel for 12v 2x current.
 

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AstroAustin said:
Unless you have sufficient battery capacity to dedicate to the electrical demands, and use the correct type of battery, simply adding more alternators WILL NOT solve your power problems..
I have stayed away from this thread because I am a newb and didn't want to step on any toes here, but tonight I'm drunk :mrgreen: so here goes... This is just wrong. The only purpose the battery serves in a modern vehicle is to provide power to crank the engine. Any other capacity is for some 'emergency' reserve. Once the vehicle is running, the charging circuit is designed to carry whatever load the vehicle requires. A car with user-added load will eventually discharge ANY battery, no matter how big, if the charging circuit is not improved.

105a + 105a does not equal 210a.
105a + 105a = lots of 105a
105 amps + 105amps actually DOES = 210 amps of real power (battery or alternator capacity)
If the engine isn't running (like I said above), whatever batteries you have installed will sooner or later discharge and die. You have to have enough alternator capacity to feed whatever additional load you want to put on your system, AND some extra capacity to recharge those batteries over a reasonable amount of time.
For the average user upgrade, extra alternator (and wiring) capacity will be sufficient, unless you want the option of using your toys when the engine isn't running.
 

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JayDubya, For being drunk... I think you have done very well. Might want to get some stronger drink...

Hope all is well with you, and good to hear from you. Jim
 

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Discussion Starter · #15 ·
JayDubya said:
I have stayed away from this thread because I am a newb and didn't want to step on any toes here, but tonight I'm drunk :mrgreen: so here goes... This is just wrong.
Don't be worried about stepping on anyone's toes! This kind of conversation challenges ideas, gives other members clarity, and paints a better overall picture of the topic. I'm glad you spoke up because if you read back to one of my earlier replies I said...
AstroAustin said:
I'll answer this question the best I can. I'm not an expert by any means and I would hate to have people toasting and frying their electrical components because of something read from me.
So thank you for throwing your thoughts in. Often times I post a topic to offer advice and share some knowledge and come away with more than I started with because of people like you.
 

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JayDubya, you did good by posting that info whether you was drunk or not.

The following is just for information.....

2 12 volt batteries (or alternators) in series will give 24 volts but not inscrease the amperage.
2 12 volt batteries (or alternators) in parallel will give 12 volts AND increase the amperage.

Examples:

2 12 volt batteries, each one 1000amps. If wired in series will give 24 volts, but still give 1000amps.
2 12 volt batteries, each one 1000amps. If wired in parallel will give 12volts and 2000amps.

If you run a battery bank, say 8 12volt batteries @ 1000amps each. If wired in parallel you'll get 12volts AND 8000amps.

If you run 4 12volt 105amp alternators, you will in fact have a 12volt 420amp electrical system. Be careful though. I am of the understanding that each alternator will take .5 horsepower away from the engine.

I had a whole write-up abou tthis one time, on my website. Just can't find it now.
 

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thats good to know jax. so does it seem better to have more capacity for the batteries in amps or is it better to have more amps from an alternator set? reason i ask is i have a stereo in my blazer that is an off road vehicle exclusively. we take it to the desert and party with it and to make sure i dont listen to the radio too long and make a no start situation i have two systems on it. one red top and one alternator for the starting and ecm and another alt and two yellow tops for the stereo.
 

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In your case I'd go with more batteries on the second electrical system. The more batteries you have the longer you can play your system without having to charge the batteries. I know some that have enough batteries to hold a system that draws upwards of 1000amps (1368 amps to be exact, 3 6500 watts amplifiers @ 456amp a piece) for pretty much a whole day without having to charge. He does run a 16volt setup, but there really is no difference in the way things are done. He also doesn't turn it up extremely loud, which it capable of doing.

In my opinion one can not survive without the other. Batteries will die without enough alternator amperage. Alternator will actually die when no load (battery) is on it. A 300amp alternator should be able to charge just about as many batteries as you can put in the van. A stock 105amp alternator will not keep up charging more than 3 or 4 batteries. Then the batteries will start draining each other. Then you have other problems.

And no. Before it's asked. I'm not saying get 4 alternators and 30 batteries installed. You can do a lot with a very minimum upgrade to the electrical system.
 

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lesterl said:
Side note, 2 batteries have 2x the connection surface area for better current transfer.
Some Diesels will run series for 24v 1/2Amps, some will run parallel for 12v 2x current.
sorry buddy your wrong here ... 24v same current ... ( the device will draw 1/2 the current ) 12 v is correct double the storage ( avil current)

so lets say you have 2 100AH batts at 12 v parellel them + to + and - to - you will have 12 v at 200ah ( Amp Hours) if you ser. them bat a + to your + and your - to the 2nd bats + and then 2nd - to ground will give you 24v at 100ah

I have run a 24 volt system beside a 12v system ( M38 Jeep with stock 24v system and run ham radio gear at 12v with no probs I ran a gen ( 24v) and an alt 12v and all was good , also taped off the 2nd bat for 12v .. but was not a great idea ...

on my jeep I run a 2 bat setup with no probs .. and I will do the same thing for my 2005 Safari for my extra ham radio gear ... LOVE glass mat batt's

Rick
 

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JaxSPL said:
. A stock 105amp alternator will not keep up charging more than 3 or 4 batteries. Then the batteries will start draining each other. Then you have other problems.
Hay jax your sorta right here .. a Alternator is not really ment for charging dead batteries .. and will put a slot of strain on it and will kill it as the batt's will suck every drop of power then can get

as for your comment of draining each other wrong word that will all come to the same voltage so if you have a dead cell in bat c lets say bat a and b shall be drawn down to the lower voltage of bat C it is best to buy all the bats at the same time same lot # 's so that thay will all react the same

Friend put 2 different bats in his van and wondered why thay would last and some times not start the van .. one batt had a 2 dead cells and would draw down the other batt until both where at the same voltage it lost 4.2v over a 12v system and the current the 2 cells would provide ( loss of 33.34 amps from 2 dead cells)

Rick
 
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