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Battery in the trunk....please school me!

Discussion in 'The Hokey Ass Message Board' started by poboyross, Sep 1, 2010.

  1. Bluto
    Joined: Feb 15, 2005
    Posts: 5,113

    Member Emeritus

    All metal battery box comes from old Dodge vans Well made and cheap!
  2. atomickustom
    Joined: Aug 30, 2005
    Posts: 3,408


    Okay, now I totally get it. Thank you - I have printed off that thread and will use it as instructions when I get around to mounting the battery in a year or two, or three...time seems to keep slipping away on my current build.

    I really like the idea that the heavy-amp wire is only live when starting the car, instead of all the time.

    Anyone have any thoughts about mounting the fuse box in the trunk, near the battery and relay? The only "con" I can think of is that the power wires for the headlights and electric fan will be pretty long?
  3. Zombie Hot Rod
    Joined: Oct 22, 2006
    Posts: 2,453

    Zombie Hot Rod
    from New York

  4. 52HardTop
    Joined: Jun 21, 2007
    Posts: 958


    Wow, chopolds, I've been away for the weekend and missed these expert words on house wiring! Yep, your right. The house and car thing don't jive. The house is made of wood! First, everything in a house , that is metal, is bonded (grounded for those who prefer that term). Everything else in the house that uses a neutral, in AC terms, is also grounded. So you are wrong in your theory that your house is not a ground circuit. Secondly, if using the car cuz it's metal to ground the negative side of the battery is a good idea, why not just go to the closest metal you can find and use that? Once again, your negative cable from your battery to your engine may carry a 100 amp load at times. It's just stupid to use anything other than a wire to carry that kind of a high amperage load. But, hey there's lots of old houses in the city near where I live that use 30 amp services still. Yep it works, but I wouldn't live in one.
  5. OptimaJim
    Joined: Nov 18, 2009
    Posts: 34

    from Wisconsin

    poboyross, I’m glad you were willing to ask about battery relocation. So many times, people just make assumptions because they are afraid to ask questions and wind up putting themselves in jeopardy. zman, NWRacing, oldguard, tjet, and badgeree are absolutely correct about venting.
    Even though our batteries have a “sealed” design, all lead-acid batteries can vent gas. Under normal operating conditions, an AGM battery will not vent gas. Since alternators or chargers can fail, the safest and correct mounting method for trunks and passenger compartments is to make sure that any possible gas venting will escape to the outside of the vehicle. All vehicles with original equipment battery locations in trunks or passenger compartments will have a vent provision that should be used.

    Our group 27, 51, 78, 34C, and 31 batteries all have ports for connecting a vent hose. Although people do it anyway, we would never recommend installing an unvented battery in any enclosed space, because there’s a legitimate, albeit unlikely, safety risk involved.

    For example, IF there is a voltage regulator failure, and IF the battery is severely overcharged, and IF this goes unnoticed, and IF the battery vents because the internal pressure exceeds the release pressure of the vents, the gasses are both flammable and toxic. This may sound like a lot of “ifs,” but attorneys and engineers get paid to plan for every worst-case scenario. If anyone has any questions about our batteries, I’ll do my best to answer them.<O:p</O:p

    Jim McIlvaine<O:p</O:p
    eCare Manager, OPTIMA Batteries, Inc.<O:p</O:p
  6. Al Von
    Joined: Nov 19, 2005
    Posts: 257

    Al Von

    +1! I have done several batteries in trunks. Mount the Ford starter relay back with the battery. I usually bolt it to the side of the battery box. Run a separate 10g or so wire up front to run everything else except the starter. That way, the ONLY time that huge cable has current running through it is when cranking. I used 00 welding cable because it is SO flexible.
  7. BulldawgMusclecars
    Joined: Jul 15, 2010
    Posts: 508


    Those are cool, but hard to find in a salvage yard around here. They go as fast as the A100 seats.
  8. newsomtravis
    Joined: Jun 1, 2009
    Posts: 562

    from pville, ca

    love the house eletricians not understanding this...hahaha........sorry guys, i had that problem with a friend of mine years ago when i tried to explain it to him.....and mounting the ford soleniod right next to the battery is the best thing that way u have a very short hot starter wire, and if it happened to chaff while driving u would be less like to have a fire.......and yes, batteries all vent, and if they are venting and u make a spark, u can have a boom, suck as i have had, right in the face, another reason to hook up the negative wire last, less chance of a spark, so, less chance of a boom, and welding cable is by far better than normal battery cable, alot more finer strands inside, and optima batteries, what can i say, nothing, best nattery money can buy, by far, u set one on the floor of my shop for 2 years, picked it up and it acted like it didn`t know it had been sitting around, and i little trick i found, for the chevy starter is instead of a wire connecting the main cable and the s on the solenoid is a small 16 gauge plate, better connection and will last forever, and another reason to use the ford solenoid is that the chevy started won`t suffer from the dreaded "heat soak" that happens alot on lowered or header equiped vehicles......just a bunch of random thoughts.........
  9. 35hotrod
    Joined: Dec 7, 2008
    Posts: 81

    from Duvall, WA

    "love the house electricians not understanding this..."
    Not understanding what? I've been an electrician for 30 years and I'll put my knowledge of DC circuits up against yours any time. While the placement of a Ford starter relay is a good idea to isolate it from heat soak, it doesn't do much to protect your vehicle from the dreaded 100 amp+ loads placed on the cable. The only time that cable carries that load is when the starter is actuated, doesn't matter which end of the cable the relay is on. Once you release the starter its load is no longer imposed upon the circuit. By isolating your 00 welding cable from the battery in the trunk and using a small wire from the source to run every thing else you are now depending on that small wire, which by the way, has much more resistance than the 00 cable, to take care of any large loads placed on or coming to the battery. Resistance + amperage = heat. Heat increases resistance. Do you really want to run headlights, heat and or AC, electric fans, ignition systems, etc. through that small wire? Do you want that small wire to carry the current of a large discharge of the battery? I don't. DC circuits are affected by wire size and resistance much more than AC circuits, a fact put in to use by a fellow named Tesla. He used that knowledge to put Edison out of the power transmission business.
    There is a difference between what will work and what is right. If you're doing your own wiring know what your loads are, use wire with the proper ampacity and fuse accordingly. Please don't tell me I don't understand how to properly relocate a battery. I think it's you that doesn't understand.
    BTW, I use a fused remote latching relay operated by an isolated control circuit to disconnect the battery from the electrical system from either inside or outside the car for security and safety.
  10. 52HardTop
    Joined: Jun 21, 2007
    Posts: 958


    I would say, that was well said! Of course there will still be guys doing the easy and fast way of using the chassis in place of a wire..
  11. newsomtravis
    Joined: Jun 1, 2009
    Posts: 562

    from pville, ca

    yep, house electricians are dumb!.....who said anything about running 100plus amps through a small wire....from the solenoid to the starter i`m talkin about 2 guage plus.....and on the ground side too, and from the engine to frame and battery to frame, and body to frame, so, wf r u talkin about........from the acc.s to the batt......i USE at least 8 guage there......go back to 3 wire school......leave dc alone!!!!
  12. newsomtravis
    Joined: Jun 1, 2009
    Posts: 562

    from pville, ca

    yeah, u can use the chassis as wire, thats why its called direct current.......d+Ass
  13. newsomtravis
    Joined: Jun 1, 2009
    Posts: 562

    from pville, ca

    yeah, and been an auto electrician for 25 years.........
  14. 52HardTop
    Joined: Jun 21, 2007
    Posts: 958


    It's not a ground. It's a negative..
  15. 35hotrod
    Joined: Dec 7, 2008
    Posts: 81

    from Duvall, WA

    An AUTO electrician! How impressive. At least you learned how to spell electrician between your first post and the next. You started out with the "don't understand" comment. I can assure you I understand how DC circuits work. Just because you figured out how to run a hot wire into a device and stick the other one to some metal to make it work makes you a real live eletrician (sic). I'm sure if you throw enough shit at the wall some of it will stick. You can call me dumb and I can tell you to go shit in your hat podna.
  16. newsomtravis
    Joined: Jun 1, 2009
    Posts: 562

    from pville, ca

    its a ground!....even a broken clock is right twice a day.....look at u 2, don`t ya need to battery cables going all the way to the, ya need romex and 3 wires......and a light swith to start it up...........heres the funny part.......i would never argue with someone about house electric.....i`m not an electrician.........but 12v......thats leave those 2 things seperate, cause they are very different.............hey, origianal guy, if you do it the way the pics on here show it will work fine........i`ve only done it that way 30plus times, and no, i`m not a house electrician....
  17. 35hotrod
    Joined: Dec 7, 2008
    Posts: 81

    from Duvall, WA

    Well, you got one thing right, you're not an electrician, Mr 12 volt. I didn't say your and other methods won't work. Regarding the circuit presented in this thread, others have posted about its advantages and another stated to "run another 10g or so wire" to run every thing else. Your post about my not understanding this-hahaha, got my attention. Then you want to say I'm dumb? While there is nothing wrong with the circuit displayed (other than possibly using undersized wire to run everything after the starter is de-energized), its main advantage is to isolate the starter relay from heat. BTW, using the "chassis as wire" is not why they call it direct current D+ass. There are applications where the negative pole of a DC circuit needs to be isolated from chassis ground. Direct current was not invented for automotive work. You may have done something 30 times that works and that's fine. I don't think you know why it works. Like I said earlier, throw enough shit at the wall and some is sure to stick. You have no information of value to me cuz I'm just dumb.
    This concludes my minor battle of wits with an unarmed man.
    Gentlemen, be safe.
  18. dirty old man
    Joined: Feb 2, 2008
    Posts: 8,912

    dirty old man

    I don't wanna get in the middle of this pissing match, but it would truly be intresting to compare the ampacity of a 1/0 welding cable and compare it to that of an automotive frame with welded crossmembers. How could this be measured?
  19. 64 a/fx
    Joined: Aug 26, 2008
    Posts: 52

    64 a/fx

    I was referred to this thread due to me posting a question in the ford fe forum. my question was and is will welding lead carry as much amperage as the same size stranded copper cable. with the wires so much smaller on the welding lead will it have a tendancy to get hotter with distance from battery to relay then to starter.

    I am running a red top optima w/ welding lead for pos and the same for a short neg to the frame/body. another neg from block to frame. having a heat sink starter problem on the fe. pretty salty motor, 427 40 over, 2-4's etc., etc,. headers are close and tight to the block and starter. (fe motors are close and tight in little comets)

    going to change the neg from bat direct to bellhousing to see if that helps. no problem with starting when cold or warm, just hard when hot. have to wait about 10-15 min after stopping from the highway before it will start again. other option I see at this time is to get a mini-starter and make a heat shield for it or a heat shield for the stock starter. headers are about 1/2" from the stock starter.

    thoughts/ suggestions??

  20. Smokin Joe
    Joined: Mar 19, 2002
    Posts: 3,770

    Smokin Joe

    If you get in a wreck, you don't want the battery shorting to a metal box in the trunk making like an arc welder near your gas tank and all the flammable crap the wife and kids stuff in your trunk... You'll have enough other problems. Keep that in mind when you mount that battery and box. Do it right if you're gonna do it. Like OMG WTF ROFL DUDE! The world is full of texting teens driving around. Just a thought...
    Last edited: Sep 14, 2010
  21. MT63AFX
    Joined: Dec 24, 2008
    Posts: 39


    Wire sizing is AWG (American Wire Gauge) 1/O 19-stranded 'regular' wire has the same cross-sectional area as 1/O Welding cable, therefore they would handle the same amperage (as long as the insulation's temperature is rated the same). It's the welding cable's flexibility that's that makes it our first choice, bending 1/O 19-stranded cable is not fun. My starter solenoid in mounted on the firewall, above the starter, because my fenderwells are fiberglass (LWG).

  22. EZrider
    Joined: Jan 19, 2006
    Posts: 46

    from Waco, TX

    [​IMG] Re: Battery in the trunk....please school me!

    <HR style="BACKGROUND-COLOR: #e5e5e5; COLOR: #e5e5e5" SIZE=1><!-- / icon and title --><!-- message -->"I don't wanna get in the middle of this pissing match, but it would truly be intresting to compare the ampacity of a 1/0 welding cable and compare it to that of an automotive frame with welded crossmembers. How could this be measured?
    Dave "

    It's as simple as doing a voltage drop test, which I haven't heard anybody mention, probably 'cause only a few of these guys would know about how to do one.
    ie; for +cable Voltage Drop (hereinafter known as VD)..
    1.Connect the + lead of a digital VM to the battery +,
    2.connect the - lead of a digital VM to the + terminal on the starter,
    3.crank the engine (w/ ign disabled so it WON'T start),
    4.READ THE VM, normally you want 1.0 Volts or less (you'll probably have more w/ long cables)
    Now for the Negative or ground cable/connection;
    1.connect the - lead of a digital VM to the battery - post,
    2.connect the + lead of a digital VM to the starter case/housing,
    3.operate the starter (as previously instructed),
    4.again read the VM, normal the -/grd side should be about half what the + is,
    my thoughts on this is if it is more than .7/.8 V you have a poor ground;
    ie; too much resistance !!
    If the VD's are too high, get bigger cable, better connections, etc.
    (the frame is a piss poor conductor compared to a cable of adequate size)

    You can then add the 2 readings together (VD+ plus VD- = VD total).
    subtract this from the battery voltage WHILE cranking;
    this is the voltage you are getting to your starter while cranking.
    Usually this needs to be a minimum of 9.5V. (some engines need more, some can use less, depends on your particular engine/starter)
    I know this is going to be too deep for some of these exspurts, but it's really easy & quick if you can understand what you're doing.
    Maybe I should make a fuckin' movie.:cool:

    old Bob :D
    55 yrs in automotive electrical,
    My first automotive job @ 16 was with Lubbock Battery & Electric,
    that was after school & all day on Saturday.
  23. sawzall
    Joined: Jul 15, 2002
    Posts: 4,731



    somehow this thread became about house wiring..

    i have used welding cable.. ) gauge or similar.

    if you need some I have some I can sell.

    pm me if still your interested..


    a few years ago I bought a cheapo chrome alternator.

    that year we headed west on labor day weekend in our 40 conv sedan.

    I kept getting the scent of raw eggs.. and in my rear view I had started to notice a strange fog..

    my battery box (an old metal thermos type cooler) is vented.. but is done so UNDER THE CAR..) fumes were circulating around the rear of the car and up to us.. had there been a back seat passenger we certainly would have known much sooner.

    turns out the stupid chrome alternator had over charged my fancy battery.. when I opened the lid of the battery box I actually witnessed the battery still venting. that was an exciting scene I am sure.

    luckily I was able to make it to a parts store and came away with a new alt and a new battery.

    had another similar issue once..
    one spring the car just wouldn't crank over..

    checked voltage, scratched head, kept trying to get the car to crank..

    for some reason I reached under the hood and accidentally touched the braided stainless throttle cable. an instant and "interesting" scar was my immediate gift..

    as it turned out the throttle cable was working as a ground for the battery because the frame / block ground had loosened.. something I didn't realize until I put a wrench on the bolts that held the ground wire in place..
  24. Troyz
    Joined: Oct 29, 2006
    Posts: 276


    I use a car audio style circuit breaker close to my battery. 1 gauge shorting to ground with a full battery & running the full length of the car (past fuel lines and tank) can really ruin your day. OH & don't run your negative cable the full length of the's called a circuit for a reason. the shorter the run the least resistance. Use gromets & ground to the body & Frame as close to that rear mounted battery as you can. bare back the metal & use star washers. You won't have problems.
  25. 39 All Ford
    Joined: Sep 15, 2008
    Posts: 1,531

    39 All Ford
    from Benton AR

    Circuit breaker is a good idea, but it is about the same distance between the starter and the battery whether it is a chassis ground or a direct run via cable from the battery, except the cable will be a better conductor.

    IMO a ground from battery to starter via cable is the best for a remote battery. Probably not necessary, but I always ground right th the starter anyway.
  26. coryw
    Joined: Nov 4, 2005
    Posts: 225

    from Omaha, NE

    Given the much larger cross section of the frame, the frame may be a better conductor than the cable as long as the connections are good. So far it is only an opinion on which is better as nobody has actually tested it that I've seen in this thread (measuring the resistance of the run or done a voltage drop test). Just to be perfectly clear, I don't know which is better either.
  27. Dakota Boy
    Joined: Sep 8, 2010
    Posts: 173

    Dakota Boy
    from Racine, WI


    200 amp ANL fuse/fue holder can be found at car audio shops


    this method will kill the motor when the switch is pushed. I'm told the fuse keeps the alternator from pushing too much juice back through the car should something happen to the battery connections

    I had to run the cables through the interior due to unibody design not leaving me any frame rails to hide them inside.
  28. 54FISH
    Joined: Jan 10, 2011
    Posts: 235


    Expurts, LMAO !! Funny thread , now who has postures of fuse box mounted in 1954 Chevy ?? C'mon show me if ya gottem !!
  29. txturbo
    Joined: Oct 23, 2009
    Posts: 1,771


    They probably got over it by's been 4 years

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