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500, 472, 425, 368 Discussion, Second Battery? in Cadillac Engine Technical Discussion; Thanks Ape, I figured the old gen/reg setup would not work with the isolator. I'm definetely going with a new ...
  1. #16
    Sasquatch's Avatar
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    Re: Second Battery?

    Thanks Ape, I figured the old gen/reg setup would not work with the isolator. I'm definetely going with a new alt. Just gotta figure out the best alt/iso setup for my needs. Take a look at the link provided earlier in this thread. it has alot of info on the benefits of upgrading from the old gen. setup to the 3 wire alt. Here's a diagram I found for wiring the iso with the alt. Is the post your referencing the one with the red ring around it in my picture?




  2. #17
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    Re: Second Battery?

    That article hits all the important points. The writer has an uphill battle to deal with in getting his point across concerning 1 wire alternators. "Joe downtown has had one on his Chevy for 78 years and it always worked for him". I can hear it now. There are legions of armchair, internet surfing, magazine reading, believe anything written in an advertisement, mis-information exchanging, never even changed a spark plug slugs out there to fight with. I wish him luck. Sometimes it's just better to let them flounder.
    Back at the ranch, your schematic has no provision for taking the regulator sensing directly from the battery so it is incomplete. Your alternator will be .6 to .7 volts too low in output to fully charge the batt. Look again at the article. They call it "Remote Voltage Sensing". Look at trucking of heavy equipment outlets for isloators that can handle some heavy continuous current. A hint at current capability will be the size of heat sink mounted to the diode pair. A typical truck installation would be for a lift gate DC motor. The isolator gets tied to the alternator output and one isolator out goes to the truck's electricals, the other directly to the lift gate controls. The lift gate will now only work with the engine running so you cannot kill the batt.
    Another good point in the article is the one made about alternator core sizing. There are tricks to increase the alternator's peak power that do little or nothing to increase continuous output. One way to increase an automotive alternator's output is to reconnect the 3 phase windings from a Y connection to a Delta. The Delta wound alternator will make more peak amperage at the expense of low output at low revs. When upgrading alternators, you want more continuous power. This will come with more cooling capability also. I like the Delco 21SI but have not tried adapting one to my Cadillac yet.

  3. #18
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    Re: Second Battery?

    I planned on using the wireing kit that MAD electronics sells for the 3 wire alt. that provides a hook up for the remote sensing that you speak of. That way the alt. should maintain the proper output to the electrical system. Then the charging wire would go to the iso and be split by the iso to each battery. I'm assuming the third wire is ground?

  4. #19
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    Re: Second Battery?

    B+, Voltage sense and ignition.

  5. #20
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    Re: Second Battery?

    Ape man, would a possible low-buck option be an old ford style remote starter solenoid between the second battery and the first (wired in parallell) with the solenoid's "S" terminal wired to an ignition feed (hot in ON, but cold in ACC)?? If Sasquatch were to wire up the stereo equipment to the second battery, it would be isolated from the rest of the car as soon as the solenoid opened. Or do you think the duty cycle of the solenoid wouldn't cut it for some reason? Alternately, a drag racing cutoff switch would achieve the same thing, but lack the automation...


    Oh, and yes, it will bolt right in. My alt. is clocked at 12.

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    Re: Second Battery?

    So B+ would go to the iso. Voltage sense. Could this be picked up at the old regulator. The MAD article talks about tieing it in at the main junction as you would get a more accurate reading. Is there a wire for the old reg. that goes to this "main junction" where I could splice to? Ignition wire?

  7. #22
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    Re: Second Battery?

    Those relays were used in plenty of other stuff besides Ford cars. I've seen them in several switching high Voltage automotive power supplies from '60's ham radio gear. Your idea seems pretty good. The one thing that could screw things up would be the coil current of the relay. They might not be rated continuously as you suspect. You could always get one and leave it hooked up as a test to see if it gets hot. They might have some sort of pull-in coil and hold-in coil winding similar to a starter. It might be an idea to see if the relay's coil can work with less current. The way to do this would be to series a string of diodes like (100 or better Volt at several Amps) in series with the ignition feed to the relay coil and find the right amount that will not pull the relay in at battery Voltage but WILL pull it in when the car's alternator has been running long enough to make say, 13.5 Volts. Each diode in series with the coil would drop the coil voltage by .7 volts (of course they have to be forward biased!). This would allow the main batt to get a reasonable charge before putting the alternator to work on the second batt. It would take a little work but would be a nice idiot proof way to go. Yes, this can be done with resistors but diodes would be much cleaner. With this setup, you simply hook all the audio stuff up to the 2nd batt, you can kill it dead and your ride will still start.

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    Re: Second Battery?

    Just found this.

    http://www.hartin.com/alt.htm

    http://www.quietcanyon.com/delco_wiring.htm

    In the second link it shows the bigger post marked BATTERY goes to the + side of the cars battery. At the top one marked BAT where does this go? Is this the remote sensing wire?

  9. #24
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    Re: Second Battery?

    Here's a better one.
    http://www.rockcrusher4x4.com/images...atorWiring.PDF


    Once again it looks like they are using the "sensing" wire to "excite" the alt. via the battery. Isn't it better to use this "sensing" wire at the main junction as suggested by mad so when there is any drain caused by running the cars normal electrical systems like lights, wipers, defogger,and so forth that the alt. would "sense" this and compensate output for this rather than just when the battery ran low?

  10. #25
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    Re: Second Battery?

    The spade terminal marked "to Bat" is the sensing wire.

    The other schematic calls it "F"

    The post on the alternator rear would of course go to the isolator.

    The interesting part is the ignition connection goes in series with the idiot lamp. This saves one set of contacts in the ignition circuit but will make your alternator look dead if the bulb opens! There were a number of model years that any suspected alternator had to be checked to see if it would start charging by jumping battery power through a test lamp to this terminal.

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    Re: Second Battery?

    Slick idea with the diodes, I was thinking a smaller relay off the alternator side of the charging side myself. (like early chevy electric choke relays) And maybe a bypass switch to allow for jumpstarting the car with the other battery if the primary becomes discharged for some reason.


    AS far as the voltage sensing part, the main junction for the car could probably be considered the starter battery lug, as all the fusible links are fed off of it. Since it has such a heavy gauge wire between that and the battery, and its not too legenthy of a run, the battery would suffice as a sensing point as Ape Man suggested. The other option would be to run a wire inside the car and go off the back of the fuse panel. While this would only be representative of part of the electrical system, it would probably provide a somewhat better output, depending on the loading of that particular branch. FWIW, I have 10ga from the back of the alternator directly to the battery, and the voltage sensing wire is landed at the battery. Works very well, but as with cars this age, the rest of the system could use some modernization to really use the extra power. (voltage at my headlights is hovering around 10 I think, engine running. Time for relays!) I only used one factory wire from the old setup. I disregarded the rest. The one was to the dash light.

  12. #27
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    Re: Second Battery?

    http://www.madelectrical.com/electri...reewire2.shtml

    If you read here and on the next page he discusses that exact reason for running the sensing wire to the main junction. There is also pics of it. That way the alt. supplies the voltage necessary at THAT point when turning on headlights and so forth resulting in not as much voltage drop off. From his explanation by running the sensing wire to the battery you are not using the alt. to it's fullest potential but rather just as a "battery charger." I imagine getting to this "junction" is a pain in the neck and therefor a lot of people opt for the easier method of tieing it in to the battery. I've tried calling this fellow and no answer. I'm interested in using his wiring kit and going with his described setup. Just cant's get ahold of him. Although he does mention using relays for headlights in another section.

  13. #28
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    Re: Second Battery?

    Ok took a picture of the back of the generator. The wire with the yellow connector goes to the plus side of the battery. I'm assuming this is for charging the battery. The other red wire coming from the post runs along the valve cover and then into the harness which is bundled together and I didn't want to unwrap everything just yet. My question is this. Is it possible to run the red wire with yellow connector to an iso then split at the iso to each battery? Therefor charging both batteries and then using the secondary battery for lights ect. during parked times with the igniton off? Or would this be to much drain on the generator and burn it up. Keep in mind this is a hearse with an electric table that turns and comes out of the car. I'll have to check my shop manual but perhaps these were equipped with a larger output gen? Thanks for all the input I'm learning alot. Here's the pic.



  14. #29
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    Re: Second Battery?

    Found this regarding generator output for the Commercial Chassis which my hearse is. My car has no AC. So I have a 55 ampere gen. even though I have no AC because all commercial chassis were equipped with those. There is an even bigger gen. that was an option for the commercial chassis that was a heavy duty 130 ampere. That is not what I have as the picture differs from what is in my car.



  15. #30
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    Re: Second Battery?

    Quote Originally Posted by Sasquatch
    http://www.madelectrical.com/electri...reewire2.shtml

    If you read here and on the next page he discusses that exact reason for running the sensing wire to the main junction. There is also pics of it. That way the alt. supplies the voltage necessary at THAT point when turning on headlights and so forth resulting in not as much voltage drop off. From his explanation by running the sensing wire to the battery you are not using the alt. to it's fullest potential but rather just as a "battery charger." I imagine getting to this "junction" is a pain in the neck and therefor a lot of people opt for the easier method of tieing it in to the battery. I've tried calling this fellow and no answer. I'm interested in using his wiring kit and going with his described setup. Just cant's get ahold of him. Although he does mention using relays for headlights in another section.

    Very good point, problem is, unlike chevies, the closest thing to a main junction that we have would be found at the back of the starter. Thats where the fusible links branch off for the headlights, fuse block, and other primary circuts. The starter has that huge wire from the battery directly to that lug, so using the battery as opposed to the main junction (in our case, the back of the starter) would provide almost no difference provided your main battery wire is in good shape.

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