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Sticky Candidate: Battery Connections

Discussion in 'GM 6.5 Diesel Engines' started by TurboTahoe, May 8, 2008.

  1. TurboTahoe

    TurboTahoe Recruit

    May 6, 2008
    The GM 6.5 Diesel has a number of areas for improvement. One of them is the battery connections. Bad battery connections can cause anything from problems starting to other gremlins such as battery charging problems, ECM not working properly, etc.

    There have been numerous complaints about the side-mount, threaded battery connections, with the connections coming loose regularly or simply not making a good connection. A weak point appears to be the GM connections, which have only 2-3 threads holding double-stacked battery cables onto the battery terminal.

    In order to dramatically improve the connections for just a few dollars, replace them with a combination of 3/8" coarse pitch steel bolts. Purchase them in lengths of 1 1/4" and 1 1/2" (for the double positives, etc.). It is recommended to also put nuts AND lock washers on. Here's what we did.

    1) Remove all battery side terminal bolts, grounds first, then positives.
    2) Take wire brush and Dremel tool with wire brush and clean EVERYTHING until it shines.
    3) Remove silly excess rubber hoods over cable ends
    4) Put nuts and lock washers on bolts.
    5) Place bolt assemblies into positive connectors, and then install them "finger-tight" into the batteries. If you want, you can snug them a little - I probably put them in about 10-12 inch-pounds- don't go any further than that - you might damage the battery terminal.
    6) Using two open end wrenches, hold the bolt head, and turn the nut/lock washer combo down, tightening the nut against the the connector, which in turn is pushing against the battery terminal. Snug them up well, probably about 10 FOOT-pounds. This is very snug.
    7) I then coat the bolts with anti-corrosion gel (e.g. from NAPA).

    The improved connections do NOT come loose any longer, and the vehicles with this modification show improved starter performance and hey - they are even bolts onto which you can put jumper cables! What would be more fun!


    More Power!

  2. jrsavoie

    jrsavoie Recruit

    May 8, 2008
    Rural Clifton, Illinois
    I use a stainless or brass bolt & nut. I also put a flat wsher behind the nut - don't know that it is necessary. I also use conductive connection grease here. Enough to block the air. A lot of electrical grease is dialectic and I don't want it blocking my connections in any manner.
  3. 94K30

    94K30 Diesel nut

    May 9, 2008
    manchester CT
    I used the grade 8 bolts when I did mine, and I added a few extra grounds while I was at it...
  4. WarWagon

    WarWagon Well it hits on 7 of 8...

    Nov 15, 2009
    The best way to fix the problem is get 2 AGM bats like Optima's with the top post connections. Then drasticly cut the side post connectors off, strip the wires back and use a crimp to put top post connector on all the cables. Naps has a tool kit to do this.

    The AGM's will just about eliminate the corrosion problems. The top post connectors will carry more current than the side post setups.
  5. bk95td

    bk95td 6.5 nut job/addict

    Nov 26, 2008
    I have the dual post batteries in my 95 LD. I had a custom 2/0 cable made to connect the top positive posts. I also had a custom 2/0 cable made to go from the side post to the starter. The engine turns over like there was 4 batteries hooked to it. I used the factory grounds but will get custom 2/0 cables made for them. The custom cables have tin coated cast copper ends and sealed with adhesive lined heat shrink tube. The 2 cables cost me well over $100 but were worth every penny. They will certainly outlast the truck. The original cables were corroded internally. They looked fine from the outside.
  6. jrsavoie

    jrsavoie Recruit

    May 8, 2008
    Rural Clifton, Illinois
    I used 2/0 welding lead and ends for a semi. I crimped and then soldered the connections. Sometimes I fill the hole with solder and then stick the cable in. I have a ratcheting crimper so it is still possible to crimp the connection after the solder cools though I doubt it is necessary
  7. Green Machine

    Green Machine Truck Don't Smoke... Well...

    May 5, 2008
    I have a hard time believing that... But I do agree that top post terminals tend to have less corrosion then side terminals.
  8. Acesneights1

    Acesneights1 New Member

    May 5, 2008
    Northeast CT
    I'll go one better. The Class 7 and 8 trucks have top post but use a stud connection similar to the gm side post. It works very well.
  9. WarWagon

    WarWagon Well it hits on 7 of 8...

    Nov 15, 2009
    Think of how thick as the metal is on top post connectors, contact area, and then you look at the thin connectors we get. I am talking about the dime/quarter thickness for ‘contact conductor thickness’ and total area of contact. The part that gets clamped to the battery is as thick as a quarter. Care to argue about the thin spot? Don’t make me get out pictures! :D

    So you have thicker metal like ¼” plus on top post connectors that go around the entire contact area vs. the dime thickness of the side post stuff.

    Imagine what connector will glow red hot first? (Like if you are arc welding with the battery. Something a bad connector will do…)
  10. I made a complete set up with 2/0 Cable and I ran #4 to the altenator and #4 from the driver side batt to the assy fuse box on the firewall, Along with a new starter it spins over very fast usually less than a couple revolutions to start even in below freezing temps, Its something every 6.5er should do, I would supect that alot of the starter issues stem from bad connections[​IMG]
  11. Brooklyn Tow

    Brooklyn Tow 9 11 Never Forget

    May 6, 2008
    Brooklyn, NY USA

    Welcome to TTS RaceDay!
    Tell Rusty, a Big HELLO from Brooklyn, NY!

    Nice engine, BTW.......Thought it was a different member (bk95td) when I saw the Alpine Green....He's built a few of them and thats the color he uses.

    What's the story with the OPS relocation and bypass switch?
  12. Ill Tell Rusty you said Hi, I relocated the OPS by using a AN 6 x1/4 np 45 about 12 in an6 line and onother adapter back to np1/4 female, I did the relay mod but ran a lead to a switch on the dash so i can overide the OPS to prime or keep me going if it fails
    heres the switch on the left the other one is a high idle on that I used a on-off-on switch
  13. RI Chevy Silveradoman

    RI Chevy Silveradoman At your service Staff Member Moderator

    May 3, 2008
    Rhode Island

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