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TLS's GM Dual Battery How-To....

Discussion in 'Commercial Snow Removal' started by TLS, Feb 23, 2005.

  1. TLS

    TLS PlowSite.com Addict
    Messages: 1,425

    The following will be a pictorial showing how I installed dual batteries in my Gas Engined '04 GMC 2500HD.

    First of all, you'll need the following tools:

    3/8" ratchet
    3/8" extension
    10mm Deepwell socket
    13mm Deepwell socket
    10mm combination wrench
    13mm combination wrench
    5/16" battery wrench
    9/16" combination wrench

    You will also need the following from your GM dealers parts counter:

    15705102 Battery tray ($20.31)
    356668 Battery hold down V-Clamp ($5.61)
    11509853 Battery hold down bolt ($0.65)

    You will need a Group 34/78 Side/Top post battery. In my case I used matching Optima Red Top batteries from Battery Mart.com


    I searched locally at several different locations. NONE had 2 that had matching build dates. Most locations only had ONE. NONE seemed concerned when I asked if they had others in the "backroom", or offered to order some in. I paid $250.57 for two matching Optimas shipped to my door.

    You will also need some various lengths of battery cable. I used some leftover from my BOSS Snowplow install, and also have access to other. I used a store bought preformed 24" side post ground cable.

    Here is where the new tray will go.

    Last edited: Feb 23, 2005
  2. TLS

    TLS PlowSite.com Addict
    Messages: 1,425

    This black firewall to fender support will be removed and discarded.

    Use your 13mm socket/ratchet to remove bolts. There are no nuts, they're built into the support.

  3. TLS

    TLS PlowSite.com Addict
    Messages: 1,425

    Personally, I removed this mounting tab. It makes dropping in the battery a little easier, and if your not using an Optima battery (which has inboard mounted top posts) it will give you more clearance to mount a top mount battery post clamp on the negative post.

    Now also remove the 4 mounting nuts attaching the fender bracket to the firewall which are shown in this picture as well.

    You also have to remove the radiator overflow tank and its hold down nut (10mm)

  4. TLS

    TLS PlowSite.com Addict
    Messages: 1,425

    This is your battery tray, hold down clamp, and fastner. Total cost = $26.57

  5. TLS

    TLS PlowSite.com Addict
    Messages: 1,425

    Then, simply install new tray using the existing firewall studs and nuts.

    All thats left is to install the new battery.

    I used a quality pre-formed 24" negative cable found in auto parts stores. I went from the aux. battery to the passenger side engine head accessory hole. You can see it go between the dipstick and the oil-fill cap. It is the black wire with the heat tape around it.

    Last edited: Feb 23, 2005
  6. TLS

    TLS PlowSite.com Addict
    Messages: 1,425

    I ran the wires across the cowl using insulated metal cable fasteners.

    You could also run across the radiator support. It really doesn't make much of a difference.

    I mounted my plow solenoid under the drivers side fender support, and found it easier to run everything across the cowl/firewall.

    Be cautious running wires in these area's, as the hood hinge spring suprisingly takes a large swing.

  7. TLS

    TLS PlowSite.com Addict
    Messages: 1,425

    Then I removed the wimpy

    600 cca AC Delco factory battery and replaced it with the other matching Optima Red Top.

  8. TLS

    TLS PlowSite.com Addict
    Messages: 1,425

    For attaching cables to the side posts, I prefer to use 3/8" stainless steel bolts and nut.

    Screw a nut on the bolt all the way to the head. Then insert that bolt/nut combo into your cable eyelet, then thread it into the batteries side terminal. Snug it, but don't get too crazy, as your going into a soft lead. Then tighten the nut towards the battery snugging the eyelet to the battery.

  9. TLS

    TLS PlowSite.com Addict
    Messages: 1,425

    The above shown method of installing dual batteries is know as the parallel method. They are NOT isolated, but instead are hooked up positive to positive negative to negative. This gives me 1600 Cold Cranking Amps (cca's) versus the original factory battery supplying only 600 cca's.

    Startups are snappier, plow raises quicker, lights dim considerably less, and voltmeter doesn't drop like it did with just the single battery.

    This setup, combined with my 145A alternator should provide pleanty of power for plow, spreader, lights, and accessories.

    I hope this helps those of you with '01 through '05 GM trucks that weren't equipped with factory dual batteries.

    Total cost for me was less than $280.

    You could do this for under $175 if you choose to use standard lead acid batteries insead of the Optima's.

    If you have a brand NEW truck, you could feasibly do this by simply buying another AC Delco battery and using it for your aux. battery, and saving even more money.

    Best bet is to order the dual battery option from the factory and modifying it to a true parallel setup.
  10. TLS

    TLS PlowSite.com Addict
    Messages: 1,425

    Thats about all for now.

    Not totally step-by-step, but the info is there for your use.
  11. OneBadDodge06

    OneBadDodge06 Senior Member
    from Iowa
    Messages: 770

    do you really notice a big difference using an optima instead of the stock battery?
  12. TLS

    TLS PlowSite.com Addict
    Messages: 1,425


    600cca VS 1600cca

    Plus I've found that dual batteries tend to last longer than single.

    And from what I've heard, Optima's tend to last longer than your typical lead acid battery. Shock and vibration is what will kill a battery. You cant get much more shock and vibration than a plow truck.
  13. REAPER

    REAPER 2000 Club Member
    from 60050
    Messages: 2,230

    <i>"Plus I've found that dual batteries tend to last longer than single."</i>

    That is a very true statement. I have dual's in my 88 GMC. One battery was new in 96 the other 97. Both have plowed every season since. They both still test at 90% power of new. Both are Interstate 1000CCA..
  14. OneBadDodge06

    OneBadDodge06 Senior Member
    from Iowa
    Messages: 770

    Yeah I can see your point. I got a die hard heavy duty b/c of the rockin and rollin. Has a heavy duty case and cells. I just thought that an alternator can only crank out so many amps so it's like trying to fill a water tower by pee'n in it
  15. TLS

    TLS PlowSite.com Addict
    Messages: 1,425

    That's not a good analogy really.

    A dual setup will take repeated hits of lifting and angling without draining as far as a single battery, thus acutally extending the life and load on the alternator. In essence, it won't be working as hard because the nominal voltage didn't drop as far down.
  16. Bad Luck

    Bad Luck Senior Member
    Messages: 741

    Nice set up and tutorial TLS.. :nod:

    Since doing mine, I re-ran my cables under the radiator cover, and moved my ground to the block. Much more clean looking. Question: What did you do about the factory battey cables on the driver side battery? Did you cut off the factory end and add your own eyelet? I wanted to use a bolt to attach the cables to this battery but was leary of doing so.
  17. TLS

    TLS PlowSite.com Addict
    Messages: 1,425

    For now, this is what I did....

  18. TLS

    TLS PlowSite.com Addict
    Messages: 1,425

    Sorry, I just realized I posted the picture and didn't type in my explanation.

    It was getting a bit late last night on that last post.

    I used the lead collar spacers supplied by BOSS to extend the side terminal's enough to accept an additional terminal. They give you a couple of these collars, and a couple of side terminal extention bolts.

    I still may end up using the top terminals eventually. However, finding good quality top terminal battery connectors isn't easy. Most are crap "Made in China" stuff.
  19. Frozen001

    Frozen001 Senior Member
    from Rome NY
    Messages: 908

    Have you tried looking at a high end car stereo shop or supplier?? they usually have some quality products.... just a thought...

  20. TLS

    TLS PlowSite.com Addict
    Messages: 1,425

    Thats a good idea. Sadly though most stuff such as this is overly ricey. GOLD plated :eek: .

    I just want a nice HD top mount battery connector.....preferably with a matching positive protective plastic cover.

    Right now, everything works well. Just want to put some finishing touches on it.