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alternator to charge batteries..

10128 Views 37 Replies 17 Participants Last post by  lilporky
does any one know how to do this??

i just have a 4 battery set-up and want to try and run my alternator as a charger..

and for more info it's in a 76 Caddi Eldorado
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buy a street charger
can you be a little more specific ..

brand .. website .. etc ..
i was kinda wondering the same thing, i was looking at my 4 guage wire from my old amp, and thinking, i could use that to charge my batteries. There has to be some way to do it, all an alternator does is charge your battery, you'd have to have a strong alternator, and it may not fully charge them like your underhood battery, but it would help when driving down the road. you'd also be better off trading in the deep cycles for some starter bateries since they are made to charge and charge.

i was aso thinking of adding another alternator to either help with charging, or do the charging on its own, becuase it would charge much faster if it were only connected to the hydro batteriers and the truck wasn't running off of it...
anyone have an input on the subject??
alternators charge at 12 volts so unless you have a 1 battery setup you're SOL. get a streetcharger if you want your batteries to charge while you drive.
I charge my batteries with my alternator. My batteries are wired in series with 4-gauge wire AND also parallel with 10-gauge. On the 4-gauge, I have a solenoid between each battery so that they're not ACTUALLY connected. And on the parallel wire, I have relays (normally closed) between each connection so that they can be unhooked at the flip of a switch.

So basically, when I hit a switch, the relays automatically open, the solenoids automatically close and there ya go. When I'm not hittin' switches the relays are closed and all batteries are being charged. Streetchargers are good, but I designed this set-up before Streetchargers came to be and it's been working great for years. :)
What a great solution. Might try that one.
now dats one good idea...
alot of wiring.. but a good idea none the less.
Originally posted by socapots@Oct 8 2003, 11:18 PM
now dats one good idea...
alot of wiring.. but a good idea none the less.
Yeah it IS quite a bit of wiring. And there aren't that many 2-pump set-ups that use 12 solenoids either. :) But I've been using this same style since around '95-96 and it works great.
Hey bouncin89, that setup sound very interesting.

Could you send me a wiring diagram of that setup to [email protected]

I'm not afraid of any extra wiring. My current setup is quite on the overkill side as it is any extra wires aren't going to hurt anything.

This sound very nice.

yes yes please share your knowledge..

plz send one to [email protected]

thanks a lot for all the info
Good idea, but lacks mechanical dependability. Charge batts traditional way, or get a Streetcharger. I dont trust relays/solenoids in hydraulics very much, why would I want them to isolate high voltage from my car system, tooo risky. I'm sure there are untold horror stories involved too. But it is a good idea.....
Originally posted by 1LOWCHERO@Oct 9 2003, 08:32 PM
Good idea, but lacks mechanical dependability. Charge batts traditional way, or get a Streetcharger. I dont trust relays/solenoids in hydraulics very much, why would I want them to isolate high voltage from my car system, tooo risky. I'm sure there are untold horror stories involved too. But it is a good idea.....
No, untold horror stories. Unless you count the fact that as I was trying to build it (7 or 8 years ago) I did go through about 30 fuses trying to get things right; but that's just a part of designing something new. I'm a designer so I typically build for failure. So I pretty much know the worst that can happen. At this point, the worst thing that can happen is I forget to turn the main switch off and the solenoid stops working. That's why I have a second solenoid in that spot as a back-up. The only other thing is that if that solenoid sticks closed and the charging is on, it could possibly start trying to charge 24 volts (as you mentioned). And of course it's seriously fused to keep this from happening. And as far as isolation goes, of course I have a battery isolator between the batteries and my alternator. And again, of course, this is seriously fused. I could go on about all of the "safety" features I have built into this thing, but it would take too long. But if you want to know something specific, let me know.
And like I said before, I would probably have a Streetcharger but I came up with this before Streetchargers came out. It works fine, so I'm sticking with it.
And another thing, to back up the entire system, I have a built-in charger so that if a need a deep overnight charge, I just unwind a cord and plug it in.
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And also, since a few people asked, you can find a diagram of it here.

It's pretty intrisic so I would only recommend it to those with patience. And as a disclaimer, this diagram is for informational purposes only. Try this at your own risk. (I have to do that part.)

Last edited by BOUNCIN89MERC2LOW97LHS at Oct 11 2003, 12:09 AM
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Its all good bro, I have designed these too and use breakers instead of fuses and commercial duty relays. I work on elevator controls and pretty much have everything to do with hydraulics at work and R & D labs. But thats another story. Too much involved with relying on mechanical means. Have fun.
I think I've got the jist of this setup.

It's all about manipulation of the current.

1) set up is a 12 volt setup with all the batteries being connected in parallel.

2) The 2nd setup is all the batteries being connected in series.

It's very simple at it's core. The theory (correct me if I'm wrong). Is that you have to disconnect each system before connecting the other.

You will basically have three main switches inbetween each battery.

Once switch to disconnect the negative to negative, another switch to disconnect the positive to positve (this is the parallel setup). One more switch to disconnect the postive to negative (this is the series setup).

Let's call swich A (negative to negative) and switch B (positive to positive) and switch C (positive to negative).

Turn A and B (C must be off) you now have a parallel setup to be charged off your alternator.

Now Turn off A and B and turn on C. Now you have a series connection.

If C is on, A and B have to be off or it will be the fourth of July in the trunk.

This system is way cheaper than a street charger (but nowhere close to being as clean).

you have to disconnect the parallel setup and connect the series setup to hit switches. Then you do the opposite to charge the batteries.

Please correct me if I'm wrong but the small test that I did it works.

Props to you Bouncin.


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That's the jist of it. Basically, when I start the car, the set-up automatically goes parallel to alternator-charge the batteries. When I want to hit switches, I flip ONE switch which automatically disconnects the alternator and turns on the first solenoid to give me 24-volts at the switch box. Then as I hit switches, the other series-noids are automatically switched on/off as needed. When I'm done hittin' switches, I just flip that first switch off, and it automatically goes back into alternator charging.

The switch that is always ON for alternator charging is a SPDT switch (ON-OFF-ON). Whenever I'm sitting around at the house not doing shit, I usually switch it to the other ON position. When I do that it automatically switches from alternator-charge, to charger-charge. Then I just run the cord out of the trunk to an outlet to charge with the built-in charger.

Also, like I said before the reason I built this (over 7 years ago) is because I don't remember Streetchargers being around in the mid-90s. And I would suggest for anyone else to just get a Streetcharger. The reason I don't have one is because, so far, this still works perfectly. :)

And far as being as clean as a Streetcharger. Right now it actually IS clean because it's behind my speakerbox. Matter of fact all you can see in my trunk are two Alpines, two pumps, the tops of 4 accumulators, and a 17" KO gleaming up through plexiglas.

And thanks for the props. I try. :)

Last edited by BOUNCIN89MERC2LOW97LHS at Oct 10 2003, 05:32 PM
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WOW! that diagram confuses the shit outta me! lol

To anyone who can make sense of that :thumbsup:

And bouncin' you are the man! That is a very interesting diagram...
most alternators [email protected] amps take or give, i charge my batts @2amps, would that be hard on the batts to charge emm with the alternator?
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