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Help with Dual Battery Install

Discussion in 'The Garage' started by Big Blzn, Jan 23, 2007.

  1. Big Blzn

    Big Blzn 1/2 ton status GMOTM Winner

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    First, I'm not very mechanically inclined like most of you. Second, I searched many threads on this issue but have not found info on excatly what I'm looking to do.

    I want to install dual batteries in my '72 but put them in the back of the blazer behind the rear seat to the side with an isolator or selectable switch to have "on" "off" "Batt. 1" "Batt. 2" or "both" options. Is there a problem with the batteries charging or just working properly being that there would be about 10' - 12' of battery wire running between the batteries and the alternator and other components? Charging issues? What gauge wire is typically run with these distances to keep the amps up. Anything else special to consider? Thanks for the help in advance. Pics would be cool if you have. does any one have a diagram they could lead me to for the wiring. :dunno:
     
  2. bear76

    bear76 1/2 ton status

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    Just mount both batt's in the engine compartment. You don't want a battery in the cab, they outgas. The isolator is all you need and follow it's directions. Good luck.
     
  3. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    Lets see if I can walk thru these... Hopefully it'll answer some of your questions...

    There's ALOT of different ways to wire dual batteries..

    1 You can simply run them in parellel and be done with it..

    2 You can have a main battery and an emergency battery, kicked in by a solenoid...

    3 You can run a selectable switch, ie:marine switch, which can run either or, or can run them in parellel, you can also add the solenoid to run it like #2 but with more flexibility..

    There are other options too..

    One thing I'll state right here that will get some people pissed.. Isolator tech is dead and there are better methods out there for proper charging... ACR's for one...

    If you run them in any sort of parellel config, your batteries should both be of equal strength and similar condition....

    Cable? The bigger the better... I run 1/0... About as big as you'd ever run in a vehicle and will handle any amp load your gonna draw thru it.. Even a 15' run.. There are charts to determine minimum wire size, I have one at work... It's a factor of amps being pulled and distance... Maybe I can remember to bring a copy home, but like I said, overkill is best.. You don't want your cable as the weak link, leave that to fuses or breakers..

    here's one that I had on the comp that gives you an idea..

    http://www.e-marine-inc.com/products/alternators/cables.html

    Type of cable....

    The general consensus you'll get in here is.... drumroll.... welding cable...

    Tho a much better choice than many cheaper, low strand count, copper wire battery cable you'll find at Autozones, etc, it is definitely not the best choice...

    Marine battery cable is a FAR superior choice imo... Not quite as flexible, but has the same strand counts, and is tinned which makes it WAY more durable and corrosion resistent.... It was my choice...

    Here's a couple shots of what I've started, tho not finished, if you didn't catch my thread... I'm in the process of building the box for the corner to eliminate the temp switch placement, etc...

    I'm running 1/0, marine switch, remote solenoid and other doo-dads... At some point, I'll be adding an ACR or Battery Mate for charging consistency and maybe another solenoid for more "flexibilty" in emergency situations.. Tho, the system is already overkill...

    [​IMG]

    [​IMG]

    Over the next month or so, I'll will transfer over my hand written, custom wiring diagrams to some format on the computer to post them for anyone interested.. I've tried to design the simplest, most bullet-proof, flexible system I can come up with...
     
  4. readymix

    readymix 3/4 ton status

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    Excuse the ignorance....

    What is an ACR? Can't remember ever hearing that acc.
     
  5. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    Nah, no ignorance... I know none of you know what it is.. I've been kinda baiting you guys with that one for a few monthes now, waiting for someone to ask... :o

    Automatic Charging Relay.. here's a tech article.. The ACR descriptions are after the isolator talk... No voltage loss, very simple in all aspects..

    http://www.bluesea.com/Article_detail.asp?Section_ID=291&id=303

    Another option over an isolator is a new product out from Mastervolt..

    The Battery Mate... I kinda like the ACR's for their simplicity.. But the ACR's are like $175, whereas the Battery Mate is about $90...

    I haven't seen them in action, but have heard awesome things about them from other marine mechanics and the boat show people... I may end up with one of these due to the price..

    http://www.mastervolt.com/product.asp?ID=307
     
  6. readymix

    readymix 3/4 ton status

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    Oh OK....

    I thought I was loosing it for a minute. ACR sounded familiar but I could not remember what it stood for.....now it all makes sense...I did not know:doah:

    You had me worried. After working with trons for 12 years I though I had heard it all.:haha:
     
  7. twodollars

    twodollars Registered Member

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    Just my two cents worth, but I would just get two new batteries, same make and model, of coursse, and wire them in parallel. It has been my experience that the more complex the electrical system, the more likely it will be to surprise you, the more difficult to diagnose, and usually rears its head at the worst moment possible. My opinion is biased, but that is what I have experienced - at work and at home.
     
  8. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    I agree, to an extent... That may be the original posters best option as he said he wasn't really mechanically inclined.. I work on stuff all day long with multiple batteries in parallel... Works fine... But you did reply to me, so I'll defend my system..

    I do like the marine switchs because they give you huge flexibilty and are a non-fail item ( in 20 yrs and seeing thousands, I've never seen a quality one go bad).. foolish not to run one if you just wanna run a couple bats in parallel imo...

    The only "non simple" part of my system is the remote solenoid... I've said it in the past on here.. It has it's benifits, but you are also adding a fail point, with the solenoid itself, and adding more connections..

    But, it is a failure you can deal with easily with a screwdriver in an emergency.. easy part to keep a spare too (I had 2 to begin with actually). But it's benefits outweigh the "complexity" easily imo.. Having your starter be "one-wire" is invaluable for many reasons. Hot start issues, long lasting cable, keeping cab feeds, ign signal wire, etc in a much safer environment, ie not at the starter lug being hammered by heat, mud, etc...

    And if you take a look at the diagram of how an ACR is wired, it's as simple as it gets... Far simpler than an isolator system... And even if it failed, it would have absolutely no bearing on any of the operations of the vehicle because of the way it's wired...

    As far as figuring out a prob? Well, I would hope anyone employing a system like the one I'm building, would be able to know what the issue is in minutes... Far simpler to figure out than hunting down some bad fusable link at the bottom of the firewall..
     
    Last edited: Jan 23, 2007
  9. twodollars

    twodollars Registered Member

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    I totally understand what you are saying - its a good system, with a good purpose. My thought is just that when all you have are two batteries, in parallel, and a one wire alternator, you usually know when it works and when it doesnt. I guess I am just tired of working behind our engineers, who add layers upon layers of wiring and "diagnostic capability", when in fact, all the new diagnostics diagnose are the new components that were added. Our military demands reliability, and at the same time requires fragile electronics that do not like dirt, water, emi, vibration, etc. Damn, sorry for the rambling. Been a long day - and guess what, had to diagnose a dead battery condition because the new "power control module", which is just a fancy automatic relay, failed and keeps draining the batteries on the damn truck.
     
  10. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    nah, it's cool man.. believe me, I have my days too, as many in here have noticed...

    And I completely understand where your coming from... I'd like to throw most marine engineers under a falling fat gal.... Bled many a time due to their idiocy...

    In hindsight, I'd suggest big blzn just do a parallel setup with a marine switch.. simple and foolproof... I've got 25 yrs of looking at car and boat DC systems to help me pick and choose what tech and techniques are reliable and worthy...
     
  11. randy88k5

    randy88k5 1/2 ton status

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  12. ntsqd

    ntsqd 1/2 ton status

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    Comment on the two batts in parallel:
    My '79 came that way. I figured GM knew what they were doing. Why make things complicated if you don't need to? Years ago I had a vehicle with two batts & an isolator. No desire to go down that road again.
    When the time came I replaced the two mis-matched batts with a pair of the same specs bought on the same visit to the same store. The truck would sit for a week or two, sometimes 3 b4 I'd start it. Those batts failed within a year. Could have been bad batts, but the next set didn't fair much better. When I sent the '79 to where all rusty GM's go I moved the batts to the replacement '91. I've since had them warrentied again.

    Based on that I recommend using the marine combiner switch. It's what I've got in the works.

    I am tempted to add an ign activated constant duty solenoid so that even if the aux batt is switched off it will get charged. Haven't yet decided if this idea has all positive & no negative aspects.
     
  13. Big Blzn

    Big Blzn 1/2 ton status GMOTM Winner

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    Dude, RYOKEN, king of all that is mechanical. I appreciate the help. The marine switch is exactly what I am looking for/to do with dual batteries. By the way, I saw pics of your battery tray in the blazer and that thing looks sweet. Nice job. Do you think its a mistake to have dual batteries in boxes in the rear of my blazer? I'll probably never put the hard top back on and will only have a soft top on in the future. Someone said earlier about the batteries will "gas" --- well so do I. Any safety issue in your opinion? Thanks for all the help fellas.:bow: :bow: :bow: :bow: :bow: :bow: :bow: :bow: :bow: :bow:
     
  14. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    Eh, I have my moments... :wink1:

    There's a few guys in here running em in the back...

    my real world opinion on it is it's not a big deal with the gases.. I ran 2 huge batteries and a marine switch in the trunk of my Chevelle for yrs without any boxes, and never noticed any buildup..

    You can alleviate ANY worrying by just running a small hose from the box vent thru the cab floor or something if you want to take care of that issue.. Thats whats recommended.... Be real simple to do compared to mounting and cabling...

    But I'd bet you be fine without it.. K5's have alot of air volume, let alone if the top is off... Most guys in here that have no intention or capabilty to run their top anymore don't even run boxes.. A few will probably post up..

    Tho if I was to do it to my K5, I'd build/buy some trick boxes.. Don't remember being overly impressed with most buyable boxes tho...

    One thing I'll tell you is, absolutely do not just run your grounds over to the frame... You'll need to run a dedicated ground up to the front too...

    With the whole "simple" vs "complicated = unreliable" issue, keep in mind, you could always add either a combining solenoid or ACR down the road between the batteries... Either of those methods will have absolutely nothing to do with overall operation of the truck... a failure will cause no issue with the truck starting or running... It can be wired just between the batteries... Whereas many wiring systems run stuff like that downstream in the system where failure will disable the truck... :doah:

    Oh, and just to reitterate, if your running em in the back, definitely get some beefy cable... At least 1 gauge, but I'd be happier seeing 0 or 1/0... Refer to that chart for help..

    Oh, 1 other thing.. If your gonna run em in back where space is not an issue, I STRONGLY recommend upping your battery size from a group 24 to #27 or even #31... Gives you, not only more cranking amps, but a much better reserve capacity.. I run a pair of #27's...

    If you need any help on the best ways to wire that stuff up, shoot me a pm... :D

    And to all, none of my posts or opinions here are meant to be combative, I just usually take some time to consider my opinions and once I form an opinion, well, I will strongly defend my position... Not that I'm not open to changing it, but I've usually developed my opinions due to some lengthy reasoning and applying yrs of real-world, *cough* wisdom *cough*.... :haha: Hopefully someone will have gleemed some helpful info from my diatribes... :doah: :o
     
    Last edited: Jan 24, 2007
  15. ntsqd

    ntsqd 1/2 ton status

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    I have.
    I really like that Mastervolt product and the ACR's, but I think that the solenoid combined with the marine switch will do what I need at less cost.

    I've been thinking for years that something like the ACR should be possible w/o going into the complexity & cost of the Hellroaring system.
     
  16. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    Cool....

    yeah, the reason I really like the ACR is how ya just wire it between the bats, and your done..

    I'll have to check into what my cost is... We get some pretty good deals on BlueSea stuff... It may only run me maybe $125 or something... If I can get em that cheap, I'd gladly pick one up for anyone interested...

    And anything from BlueSea is absolutely topnotch quality, those guys make some killer product.. My bat switch is thru them and they are much nicer than the Perko's or Guests...
     
  17. Elevator Man

    Elevator Man 1/2 ton status

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    when running the batt switch and the selonoid, is the selonoid just for charging the aux batt when its tured off. I'm tryung to figure out the concept could someone show me a scematic?
     
  18. lak2004

    lak2004 1/2 ton status

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  19. Big Blzn

    Big Blzn 1/2 ton status GMOTM Winner

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    Man ryoken, thanks for all the knowledge. I'll start this little battery venture in about 8-10 weeks. Thanks again fellas.
     
  20. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    here's one way to do it...

    [​IMG]
     

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