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Thread: Ground/earth related. Do you really NEED a cable from battery to engine block? Myth?

  1. #1
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    Ground/earth related. Do you really NEED a cable from battery to engine block? Myth?

    If you have multiple wires going from the engine block to the chassis + a wire or two from the battery to the chassis, why then do you "HAVE TO" have a cable going from the battery to the engine block?

    Trying to finish off my battery disconnect switch and thanks to bumping into an article online (https://www.w8ji.com/battery_wiring....unted_battery:), I'm losing my sh*t and paranoid that I'm going to cause damage to my electrical system and/or worse.
    (I don't want to drill a hole in my firewall to run a cable to my block/bellhousing if I don't need to)

    Under "Front Battery System" in that link I provided, he states:
    "Front battery, engine block common for all high currents. High currents (over 50A) must NOT be grounded to chassis. Chassis common for all accessories.
    Never ground the very heavy high-current lead to vehicle chassis with front mount batteries. Always ground the heavy lead to the block, bell housing bolt, or some other solidly-connected (no insulating gaskets) engine component."

    And under "My trunk mounted battery", he goes on to say:
    "Rear battery, chassis common for all high currents. All currents can be grounded to chassis.
    The vehicle chassis should be the ground lead. The battery should be high-current grounded to the vehicle chassis with short direct leads. The engine block should be high-current grounded to the vehicle chassis.

    The engine block is grounded to the chassis through a heavy "starter size" cable."

    Like wtf? He makes out like you'll die if you don't connect a cable from the battery to the block in a front battery system, then acts like it's no big deal earthing everything to the chassis in a rear mounted battery setup.
    So, is connecting a cable from the battery (kill switch, in my case) directly to the block not required and what he wrote = BS?
    Last edited by Mr. Smith; 02-05-2019 at 10:22 AM.

  2. #2
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    Not sure why the insistence on cable to block with the front mount battery. For the rear, what he is saying is that you need to ground the engine block to the chassis with a thick ground cable. And you should ground the battery to the chassis with a thick, short, ground cable. He is not saying you need to run a cable from the battery to the block. Just that both should be well grounded to the "earth" / chassis.

    HTH,
    Jason
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  3. #3
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    Quote Originally Posted by JasonS5555 View Post
    Not sure why the insistence on cable to block with the front mount battery.
    Same.

    Quote Originally Posted by JasonS5555 View Post
    For the rear, what he is saying is that you need to ground the engine block to the chassis with a thick ground cable. And you should ground the battery to the chassis with a thick, short, ground cable. He is not saying you need to run a cable from the battery to the block. Just that both should be well grounded to the "earth" / chassis.

    HTH,
    Jason
    Yes I understand that, knew that already and it makes sense.
    The only thing I don't understand is why he/everyone insists on saying "you HAVE TO connect a cable from the battery to the block" in a front battery system.
    If he/they can't explain exactly why it's required, I just think ignorance and sheep mentality.
    If you should ground the battery negative to the chassis in a rear battery mount setup, then why can't you do the same for a front mount?
    It didn't seem like he meant "ideally, you should(n't)....", what it came across as was "if you don't connect the negative to the block in a front battery mounted setup, the high currents from the alternator and starter will fry the lower current circuits such as your lights, computer...".
    He pretty much wrote that ^ but can't find it now.
    Last edited by Mr. Smith; 02-07-2019 at 10:35 AM.

  4. #4
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    Quote Originally Posted by DGS View Post
    The starter and alternator ground thru the block. I would ground block to battery on a front battery system and for a rear battery ground from body to chassis (frame) and from chassis/frame back to block in the front . The chassis/frame will handle the loads, but the connections have to be clean and tight. You want large battery cable size like 1/0 gage. Better larger than too small. If you put your own ends on the cables, solder the terminals on. You don't want any loose connections. Do it right, do it once. You also don't want current conducting thru any carbon based vacuum lines or hoses or trying to ground thru the coolant to the radiator and eat it up. Once the coolant starts to degrade, it becomes conductive to electricity. A lot of setups run power off starter . You want at least as large of a negative cable to block as the total positive power feeds you are supplying to all of your accessories. Without a ground to the block, it will seek any route including brake lines and hydraulic clutch lines and mounts if they are grounded to the frame/body.
    So why doesn't it do that and cause problems in rear battery mounted setups where you don't earth to the block????????????
    Makes no sense whatsoever (that it'll only do that for a frount mount and not rear mounted battery setup).


    Just so I'm clear, my engine block is earthed to the chassis by multiple cables. Just not from the battery.



    Thanks for the replies.

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    Quote Originally Posted by DGS View Post
    In new vehicles the positive runs from trunk to engine compartment fuse panel/starter. The negative is body/frame grounded in rear and frame/body to block in front. Saves wire and weight. Would be interesting to see the write-up.
    Yes.. and just about every other car with the battery in the back and engine in the front.
    But why can't you just do the same in a front battery setup????? That is the question. The only thing I want answered.



    I ended up drilling a hole in my firewall today and running a cable through to the kill switch Was tired of stressing over it and figured my question wouldn't get answered, plus wanted my car back on the road, so I just said "f it" and done it.
    Stressful sweaty job but I'm glad I done it now... unless I find out that I didn't have to do it (cable from neg-battery/kill-switch to block).
    Might be better off not knowing the answer now..

  6. #6
    Advanced Tuner Dr. Nopps's Avatar
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    I'm surprised none of the audiophiles have chimed in about "The Big Three". You've basicly adressed 2 out of 3 here already. The only thing left is a fat #0 wire run directly from the hot side of alternator to the +POS battery terminal.

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    Quote Originally Posted by DGS View Post
    Regardless of front or rear battery set-up, the block is sufficiently grounded directly to the negative battery terminal by design. In the case of a front battery, the shortest block ground path is to the negative terminal of the battery. Whatever you read was in error. You don't want any opportunity for current from starter or alternator to seek out any alternate ground path or loop. This will prevent fires and burned up components. The same applies to the positive side. The starter grounds to block and back to negative battery terminal. The starter solenoid is wired directly to the positive terminal. The alternator is grounded to block and back to negative battery terminal. The alternator is wired directly to the positive battery terminal. It may or may not pass thru the starter connection. Many positive fuse block loads are tapped into this connection at the starter or wired to the positive battery cable. You have direct loops/current paths to and from the starter and the alternator to the battery terminals. This prevents any unwanted current flow paths. In most cases, the goal is less wiring which cuts vehicle weight and cost.
    Soooooooo.. again..
    Why do you need a cable from the battery negative to the engine in a front battery setup but not in a rear battery setup?

  8. #8
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    None of this shit makes any sense. Bunch of contradictions.

    Front mount battery: Never earth to chassis
    Rear mount battery: Battery should be grounded to chassis


    Get stuffed

  9. #9
    Quote Originally Posted by Mr. Smith View Post
    None of this shit makes any sense. Bunch of contradictions.

    Front mount battery: Never earth to chassis
    Rear mount battery: Battery should be grounded to chassis


    Get stuffed

    a ground from the battery neg should never be longer than 3ft. regardless if its in the front or back of the car thus battery negative to chassis in a rear mount situation.
    once you're over 3 ft you start to get interference. when you ground to the block you would also have ground straps to the chassis to make the engine and chassis a single ground.

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    Quote Originally Posted by Erick@HPTuners.com View Post
    a ground from the battery neg should never be longer than 3ft. regardless if its in the front or back of the car thus battery negative to chassis in a rear mount situation.
    once you're over 3 ft you start to get interference. when you ground to the block you would also have ground straps to the chassis to make the engine and chassis a single ground.
    Not true. Depends on cable thickness and other things.
    My battery negative goes from the battery to kill switch to engine head. Total length is around 105cm. Over 3 feet.
    My cables are around 6mm in (inner) diameter, which = 2 or 3 gauge = about 28mm squared cross section.
    Cable length 1.05cm + Amps 210 + Voltage 12.65 + Cross section 28mm squared = 0.27 voltage drop
    Cable length 1.05cm + Amps 50 + Voltage 12.65 + Cross section 28mm squared = 0.06 voltage drop
    = fine (also factor in I have other ground cables), and if my cables were 0 gauge, the voltage drop would be twice as good/less.

    I have already mentioned (twice) that I have multiple (3) cables from my block to the chassis.


    To everyone,
    This topic is about: Why do you need to run a cable from the battery negative to the engine in a front battery setup (when your block is grounded to chassis via cables)?
    I do not wish to read any other info or reply to comments which don't answer my question. It's a waste of our time.

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    Bottom line is like he stated in the article. The negative frame path (plus the frame to engine block cable) has less resistance than running a negative cable from the rear mounted battery to the block.

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    Quote Originally Posted by DGS View Post
    Bottom line is like he stated in the article. The negative frame path (plus the frame to engine block cable) has less resistance than running a negative cable from the rear mounted battery to the block.
    Are you for real? How many times must I repeat myself before you understand my question??? 10x? 25?
    This is your 7th post now (which I'm aware of. You could've deleted more.) going on about something else I didn't ask about or I either already know or don't care to know or saying I misread something (how ironic)...
    Stop going on about batteries mounted in the rear and other random info like saving weight and costs ffs.
    Like, are you trolling? Really old? Really drunk? Mental disorder? All four?

    Imagine you started a topic, asking why a Ferrari LaFerrari is faster than a Toyota Camry and I posted about the Ferrari being coloured red and how they paint it. Then you told me that isn't what you're asking and repeated your question. Then I came back and told you where the Ferrari was built and how much it costs to buy........... that sort of thing........ 7 times. You've done the same thing here to me.

  13. #13
    Tuning Addict 5FDP's Avatar
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    Did they not add the battery to block because of the fact that the engine is set on rubber engine mounts?

    They add the extra ground for that reason. Then in a rear battery setup they have you wire the engine block to the body/frame and then battery to body/frame in the trunk.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

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    All of the info was provided in the posts. Put together all of the info instead of bashing people for trying to help you out. Not a troll.

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    Yes, I deleted my posts that contained the info you chose to overlook.

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    Advanced Tuner mbray01's Avatar
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    There is no end of the world because the battery isnt grounded directly to the block. The only reason you want the battery grounded to the block on a front mount battery is because the engine carries the highest amperage load(starter, Alternator) and you want grounding that provides the path of least resistance. Its nothing more than that. if its a pain to hook directly to the block, then dont. As long as you use adequate cabling and good clean connections, and connection points. then you will have zero issues.

    Path of least resistance. nothing more. nothing less.
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    Quote Originally Posted by DGS View Post
    Yes, I deleted my posts that contained the info you chose to overlook.
    None of your posts helped answer my question. You misread my question repeatedly and continue to put the blame on me (not understanding...). It's not me with the problem (understanding), it's you. You are to blame. You are in the wrong. You don't understand. You. Understand? YOU.
    You also have a major attitude problem, hence why you deleted your posts which you thought were helpful. What type of person does that?
    Plus half of your (latter) posts were just you being a smartass/dyck, which I didn't bother replying to, like I should've done to all your time-wasting crappy posts here.
    You also lie a lot and talk a lot of shyt. Like me "bashing people for trying to help" (I just told you I've repeated myself to you a bunch of times and yet you still don't understand what I'm asking. Don't make out like I'm the bad guy here and that I'm "attacking" other people. Typical behaviour from someone like you), like me not providing a source or some crap like that (even though I posted a link in my original post), like me misreading something from the article I provided a link for (not true), like I chose to overlook the info (no info from you regarding my question, just garbage), like "All of the info was provided in the posts" (not true)......... Full of crap.

    I don't like you one bit. Stop wasting my time. GTFO of here. Go cry to a mod now to have me banned.
    Last edited by Mr. Smith; 02-19-2019 at 03:12 AM.

  18. #18
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    Quote Originally Posted by mbray01 View Post
    There is no end of the world because the battery isnt grounded directly to the block. The only reason you want the battery grounded to the block on a front mount battery is because the engine carries the highest amperage load(starter, Alternator) and you want grounding that provides the path of least resistance. Its nothing more than that. if its a pain to hook directly to the block, then dont. As long as you use adequate cabling and good clean connections, and connection points. then you will have zero issues.

    Path of least resistance. nothing more. nothing less.
    Finally. The answer to my question. Thank you very much.
    Last edited by Mr. Smith; 02-19-2019 at 03:19 AM. Reason: changed "an" to "the"

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    Finally you understood.

  20. #20
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    Quote Originally Posted by DGS View Post
    Finally you understood.
    Lay off the moonshine.