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Dual Battery/ Electrical Question please help!!!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by dawson444, Dec 29, 2002.

  1. dawson444

    dawson444 1/2 ton status

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    Ok here is my deal, i have a yellow top optima and a red top in my truck. I am trying to figure out how to wire them together. I want to isolate them from each other so I can run the yellow top down w/ lights, winch, etc. and still have the red top to start the truck. Whats the best way to do this? I don't really want to get into doing one of the isolator kits ($$$). I am thinking about running a marine battery stiwch like this one [​IMG] If I do do that there are 3 places to hook up wires on it. What should I put where? Do I need a switch that beefy? Thanks!
     
  2. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    I don't know what kind of money you are willing to spend but, I went with a 90 AMP surepower isolator and required wiring and it cost me around $100.00. There is nothing better than knowing you have done the job correctly the first time and don't have any electrical fires in the future from trying to save a buck. The switch you have shown will work but you have to keep manually switching it back and forth which will over time become a pain to deal with. I am sure that the switch you have shown is fairly cheap in price and if you are on a budget it will work for your needs and will be safe. The biggest thing to remember is to use the proper size battery cables for the amount of AMPS you intend to draw from the auxillary battery.
     
  3. bigjbear

    bigjbear 1 ton status Staff Member Moderator

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    You will want to go w/ the HD version of that switch. Might want to look at the max amp draw for your winch and compare it to the rating for the sw you have shown.
     
  4. Highlander

    Highlander 1/2 ton status

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    What size Alternator are you using? What ever you go with make sure that the Relay or isolator or that marine battery switch will handle the amp's
    When I put Duel batterys in my 83 I used a 200amp relay from Wangler power products, I have a 140 amp power master alt. I used 1/0 welding cable. I still need to get the Wanglers Battery Manager to complete it all. But for right now both batterys are joined only when he truck is being started and running.

    Eric
     
  5. Batmanjr

    Batmanjr 1/2 ton status

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    Isolators are easy to wire and they aren't too expensive! I have a 160 Amp isolator on my 140 Amp Alternators going to my 3 battery setup on my 83 Diesel Blazer! It really isn't that hard! It really only gets expensive when you want more than 2 banks! I have two banks, one bank has 2) yellow top optimum, and the other bank has 1) 900 Cranking amp Die Hard.... The alternator is a 1 wire alternator that is directly connected to the Die Hard, The Die hard runs the lights radio, and the rest of the truck, while the optimum runs the diesel starter and soon a winch! I can jump myself, I've never had battery problems, and my diesel starts like a primed gasser! IT literly takes 1 Second to start! If you have more questions, Pm me!
    PS, the isolator I got was from JCWHITNEY! I don't normally buy there crap, but it has never had a problem and all a isolator is, is a set of diodes! It also has a life time warrenty,, so if I do have problems , I can get it replaced! /forums/images/graemlins/thumb.gif
     
  6. mattyblazer

    mattyblazer 1/2 ton status

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    www.Westmarine.com
    [​IMG]
    Has a page with information, its called "the west advisor"

    This is some of what they have to say.....

    Creating a reliable battery system

    Introduction
    "Any boat that relies on its engine(s) for propulsion and travels more than a short distance from shore should have two independent batteries capable of starting the engine(s)." That kind of platitude is so darned obvious, you probably wonder why we'd waste your time with it. But the fact is, the statement is insufficient and misleading. This West Advisor will try to explain why.

    Due to the scarcity of tow trucks at sea, boaters have to be more self-sufficient than their land-bound counterparts in RVs and automobiles. Judging from the statistics we see on boat breakdowns, the two most frequent requests for assistance are because, 1) "I'm out of gas!", and 2) "I can't crank my engine. " We'd also venture to guess that the reason most boaters can't crank their engines is because their batteries have been run down by too much use and too little charging, as opposed to starter motor failure or some other malady.

    Assuming the boat is equipped with two adequate batteries, why would they both end up dead at the same time? There are at least three probable causes:

    * Poor battery charging by the engine. This may be masked by near-continual battery charging, via shore power, when the boat is not in use.
    * Inadequate battery capacity, forcing the boater to use both batteries simultaneously (switch on the BOTH position) to run DC loads.
    * Lack of true isolation of the engine starting bank and the house bank, resulting in unintentional simultaneous discharge.

    The latter reason is the least understood by boaters, and it's due to a simple myth: because my boat has a big red OFF-1-BOTH-2 battery switch, it therefore has isolation between its battery banks. To that, we say:

    Nonsense!
    Most single-engine boats produced in the last thirty years are supplied with two nearly identical (and under-sized) marine batteries. Generally of the Group 27 designation, both batteries could be used interchangeably for starting and house loads. Prior to starting the engine, the operator would turn the battery switch to the BOTH position so that he or she had the full cranking power of the batteries. Once the engine started, the operator would leave the switch in the BOTH position while powering to the day's destination so that both batteries were charged. Once a sailboat began sailing sans engine, or a powerboat dropped the hook, the operator would (in theory) turn the battery switch to the 1 or 2 position, so that the other battery would be reserved for starting. When it was time to crank the engine again, the battery switch would be turned to BOTH, or possibly to the reserved battery, and the engine would be started.

    The problem, of course, is that this requires a lot of thought on the part of the operator, who is trying to relax in the first place. The inevitable result is that at some point, the boater accidentally leaves the battery switch in the BOTH position, resulting in two very dead batteries.

    We also take issue with using two identical batteries since boats have two distinct types of loads: long duration, low amperage loads when the engine (charging source) isn't running, and high amperage, short duration loads while starting. Using a pair of deep-cycle or dual-purpose batteries, or worse yet, starting batteries, for this application is inefficient.

    What's the solution?
    We strongly recommend that you select and wire your batteries differently from the way the factory wired them. Use a stout starting battery to crank your engine, based on your engine's cranking requirements. Use a larger house battery with triple the capacity of your daily DC requirements. Now this is where it gets complicated: we DON'T recommend the use of a traditional OFF-1-BOTH-2 battery switch. Instead, consider using three OFF-ON battery switches as follows: one switch to connect your starting battery to your starter circuit; one switch to connect your house battery to your boat's distribution panel; and one switch to parallel your battery systems if either battery fails.

    With this switch set-up, you simply turn your engine and house switches to the ON position whenever you are onboard, whether anchored, starting your engine, or sailing. The battery parallel switch remains OFF unless there is a complete failure of either battery bank or you have run your starting battery down trying to crank a reluctant engine. When your engine is off, the starting battery is safely isolated from the house loads. It cannot be discharged, even if you leave your stereo on all night, listening to Jimmy Buffett and blending margaritas.

    How do I charge both banks simultaneously?
    By isolating starting and house banks, you face a challenge trying to charge them from a single source like single-output chargers or alternators. If you violate the "separation" of the two banks, you face the probability of two dead batteries due to "operator brain-fade". That's why we are great believers in the West Marine Battery Combiner and Heart Pathmaker, Balmar Dual Output Alternators, and to a lesser degree, battery isolators. These products sense the voltage of the battery banks and connect the batteries together whenever one battery's voltage is elevated. Both banks charge simultaneously and remain combined until the voltage drops, whereupon they are disconnected from one another. It's much like having a very attentive engineer flip your battery parallel switch on and off at exactly the right moment. The result is maximum charging performance for two banks, and complete isolation of the two banks to ensure that you can start your engine.

    Do I have to scrap my present switch?
    While you don't have to, we strongly recommend the use of simple-to-understand OFF-ON switches. Shoot, even your brother-in-law can probably figure out how to operate an OFF-ON switch, but might be completely baffled by a OFF-1-BOTH-2 switch. Alternatively, you can use your current battery switch, plus a second OFF-ON switch, but we think it becomes complicated to understand what each switch combination accomplishes. As an added benefit, the fact that the battery switches are seldom, if ever, operated while underway greatly reduces the chances of damaging your alternator by accidentally opening its output circuit.



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  7. 79Beast

    79Beast 1/2 ton status

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    I am in the process of adding a 2nd battery to mine. I'm using a 400 amp continuous duty solenoid. I will run switched ignition power to it so that whenever I have the key "ON", my batteries will be in paralell. When the key is "OFF", the 2nd will be isolated from the rest of the system. I'm gonna use 4/0 because my batteries are goin in the bed of the truck. It will all end up at a bus bar/terminal block on the fender.
     
  8. imiceman44

    imiceman44 1 ton status

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    Hey were did you find a 400 amp continuous duty solenoid, and how much?
     
  9. Batmanjr

    Batmanjr 1/2 ton status

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    I would like to know as well! AS I still have two banks to add to my truck, I would like the ability to add and subtract them when I want to! Thanks! /forums/images/graemlins/thumb.gif
     
  10. 74Chev

    74Chev 1/2 ton status

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    I use a switch made by Perko which is almost identical to the one you pictured. I use it with 2 Yellow tops. I am a commercial fisherman and have used these types of switches at sea for years without a failure. Yes you do have to switch is back and forth, but it takes about 2 seconds. There is always instructions that come with the switches and the connection diagram should also be molded into the back of the switch (mine is.) The output wire (starter) should be wired to the output lug. Then wire with heavy guage, I use 2/0 cable from battery 1 to terminal 1 and battery 2 to terminal 2, its that easy. You can now shut off power to the truck, start with 1 or 2 or combine both together, and also connect accessories to 2 and switch to 1 if you are using them with the truck turned off and always have 1 in reserve at full power to restart even if 2 is dead. I usually run in position 1 or 2. This is because if you have an alt. failure or leave lights on and you are switched to both it will kill both batteries leaving you stranded. I have my 74 pickup and my commercial fishing boat wired this way with no problems ever.
     
  11. HarryH3

    HarryH3 1 ton status Author

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    One thing to keep in mind when you're using one of those switches on a rig that's fuel injected... Everytime that you turn it to the off position, the ECM will be reset and have to start learning the nuances of your engine all over again. Not a major pain, just something to be aware of. /forums/images/graemlins/cool.gif
     
  12. JP's K5

    JP's K5 Registered Member

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    I used a heavy duty Perko marine switch with 4 positions. It worked great. I switch to the dual setting every so often to keep the second battery fully charged. I think the switch was about 25 bucks. I used some really heavy battery cables to hook the two together. The nice thing about the switch is that it has an off setting that disconnects both batteries. It makes it nice when you want to work on the truck. These switches should handle the power, they come on most boats with dual battery setups. I've ran mine for about 2 years now. Hope this helps.
    Jared /forums/images/graemlins/k5.gif
     
  13. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Does TBI really remember anything about your engine? I know other EFI's do. Just curious if TBI is that smart or not.
     
  14. HarryH3

    HarryH3 1 ton status Author

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    Yep, it makes short term corrections to the fuel map, based on feedback from the O2 sensor. If it senses that it has to make an adjustment to the same part of the fuel map for a certain period of time, then it stores that information in long term memory. The "new" setting for that data point is now the standard setting, unless the computer starts seeing a problem again, at which point it will change the data point once again.

    If the power to the computer has been off, then the memory gets erased and the computer defaults back to the baseline program that is stored in the EPROM. It typically takes 20-30 minutes of driving after the engine has fully warmed up before most of the correction table has been rebuilt.
     
  15. imiceman44

    imiceman44 1 ton status

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    Thanks for that info, I knew this is what happens but I didn't know how long it takes for the computer to reprogram.
    So basically a trip of one hour straight driving should fix that?
     
  16. HarryH3

    HarryH3 1 ton status Author

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    Yep, but not an hour of cruising at the same speed on the freeway. It needs to be varying speeds, loads, etc. so that it can sense as many variables as possible. /forums/images/graemlins/cool.gif
     
  17. imiceman44

    imiceman44 1 ton status

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    gotcha /forums/images/graemlins/thumb.gif
     

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