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Ideas???

Discussion in '1982-Present GM Diesel' started by Judd, Dec 17, 2002.

  1. Judd

    Judd 1/2 ton status

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    Got a idea I thought about running by ya'll. I would like to run a battery isolator between the two batteries for several reasons. Problem #1. The 6.2 needs alot of power to crank well. Could I isolate the two batteries then place a Ford starter soleniod between the batteries and wire it to the start switch so that when I crank it, it would parallel the two batteries? Sorta of a poor mans Painless Wiring battery controller. 2nd thought; Since I had the soleniod between the batteries, could I wire the batteries in series instead of parallel so I could get 24volts to the starter? I've done the 24 volt thing before on starters and haven't had a problem but would this be OK for everyday use or would it burn starters out fast? The rest or the electrical system should be fine as the switch turns off the accessories when it's in full start mode{I think, please correct me if I'm wrong on this}, the soleniod would cut off once the key was released back to "run" and I would be back to 12 volts.
    Please read over this and see if I'm barking up the wrong tree on my line of thought.
     
  2. imiceman44

    imiceman44 1 ton status

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    Your idea can work, the only flaw is the starter is not going to last you long running on 24 Volt.
    You might get away with doing it a few times, but soon it will roast.
    The rest of the idea works.
    Now I don't know if the 24 volt starter is better, you could get one and put it instead.
    Now the only other problem would be charging that second battery.
    If you have it in series, it can't be charged by that alternator, unless in your wiring you make sure you disconnect all lines from the alternator to the second battery when cranking.
    Because you will have both batteries hooked to the same source for 12v and in the same time linked in series.
    Be carefull.
    /forums/images/graemlins/thumb.gif
     
  3. arveetek

    arveetek 1/2 ton status

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    Most military trucks use 24 volt starters. They have dual alternators, and lots of resistors and other parts. Most people yank that out and run a regular 12 volt system.

    Two good cranking batteries, good starter, and good cables are more than enough to start the 6.2L. I don't think it would gain you anything but headaches to attempt what you're proposing.

    Casey
     
  4. Judd

    Judd 1/2 ton status

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    Good points, think I'll just do the isolator and the Ford soleniod thing. Just parallel the two batteries with the soleniod. That way I should always have at least one good battery, even if I kill one from winching or leaving the lights on. Thanks for your opinions /forums/images/graemlins/thumb.gif
     
  5. DieselDan

    DieselDan 1/2 ton status

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    The hard part is charging the battery(s). If you isolate one you must isolate it when charging also. If they are wired parallel when they're being charged the altenator sees one big battery. One battery can be overcharged and/or the other undercharged.
     
  6. imiceman44

    imiceman44 1 ton status

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    Hey Dan, you seem to know your diesel engines very well but your electrical needs some brushing up.
    /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif
    If you have 2 batteries in parallel not isolated, the charge will equalize automatically, meaning juice will discharge into the dead battery untill both have the same voltage.
    If you are charging them unisolated they will end up having the same charge, the problem with this setup is that if you have a dead, as in not chargeable battery, then you will not have enough charging in the good one because the voltage drop is going to be so bad and whatever charge goes into the good battery is imediately discharged in the bad one.
    Theoreticaly I studied , and it actually happened to me twice in my fathers Starcraft conversion Van.
    /forums/images/graemlins/thumb.gif
     
  7. DieselDan

    DieselDan 1/2 ton status

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    No we're on the same page. I agree the charge will equalize between the two batteries given enough time , But if you discharge one (from winching lets say) then charge both you will end up with the over/under problem. Actually I think you will shorten both batteries discharging one more than the other (and letting the voltage equalize).

    I am VERY familiar with the bad (cell) battery "no power" routine. Everything that I work on has at least two (up to EIGHT for the M88 Hercules /forums/images/graemlins/eek.gif) batteries. We always replace batteries in sets to prevent shortening their life. /forums/images/graemlins/wink.gif

    "Let's see U6TL battery is $89.00 delivered X eight = OUCH" /forums/images/graemlins/grin.gif
     
  8. arveetek

    arveetek 1/2 ton status

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    He can use a battery isolator that is commonly used on motorhomes which have two 12 volt systems, one for the engine, and one for the coach accessories. This allows both batteries to remain separate, but still be charged by one alternator. It has one input from the alternator, and one output for each battery. Then, using a solenoid big enough to carry the amperage, he can connect both batteries together temporarily for starting purposes. In fact, a lot of motorhomes have a button on the dash labled "emergency start switch." This allows the owner to start the engine off of the coach battery in case the chassis battery is dead. He just pushes the momenty switch, closing a large solenoid, and joining the two systems togther while he cranks the engine. If it were wired into the ignition switch, it would all happen automatically.

    Most RV stores have these battery isolators and solenoids in stock, although a typical Ford starter relay will work well for the solenoid.

    I don't think it's really worth doing though, myself! I don't think there's much advantage in it. If there is that much demand for 12volts from added on accessories, I would leave the stock system alone and add a third battery with an isolator.

    Casey
     
  9. 55Willy

    55Willy 3/4 ton status

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    Try your local Auto Parts place too. Instead of a basic ford set up get a switch that is made for this purpose. It'll last longer.
    The ones we stock are a SW- 171 which is a Standard brand.
    the switch is rated at like a 80 amp draw or 60 continous. ( don't quote me on that) LOL.
    they run about $15, where as the ford style is only $6.99

    -Jeremy
     

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