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Starter Solenoid and Battery Location

Discussion in 'The Hokey Ass Message Board' started by Doctor Detroit, Jun 19, 2013.

  1. Doctor Detroit
    Joined: Aug 12, 2010
    Posts: 1,004

    Doctor Detroit

    I'm relocating the battery in my '51 Merc to the trunk. Originally, it was under the hood with the starter solenoid right next to it.

    Should I also relocate the starter solenoid to the trunk, or does it not matter as long as I have a heavy enough cable between them?

    Is there a reason why I couldn't/shouldn't put it under the dash on the passenger side?

    Thank you in advance.
  2. Get the solenoid as close to the starter as you can. You can mount it out of sight under the pass toe board free from the exhaust pipe. A 1/0 cable will work. I run a 2/0 from trunk to up front with very little drop in V.
  3. Doctor Detroit
    Joined: Aug 12, 2010
    Posts: 1,004

    Doctor Detroit

    Anyone else have info to share on this?

    Posted from the TJJ App for iPhone & iPad
  4. 2racer
    Joined: Sep 1, 2011
    Posts: 960


    what he said...
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  5. 1971BB427
    Joined: Mar 6, 2010
    Posts: 5,515

    from Oregon

    Agreed! Regardless of where the battery is, the solenoid should be close. Within 3'-4' is fine. I also have the battery in the trunk on both my cars, and run 1/0 fine strand welding cable. Not all 1/0 is equal, as fine strand welding or battery cable has twice the amp rating of regular 12-16 strand cable.
    Both mine are Chevys, so solenoid is on the starter. never had them miss a lick when I hit the key.
  6. aaggie
    Joined: Nov 21, 2009
    Posts: 2,527


    Leave the solenoid under the hood where you can get to it. It is a source of power when you need to troubleshoot and if you need to bump the engine over during tune ups etc.
  7. More realistic to increase the cable size instead of increasing the ignition wiring gauge if you relocate solinoid to the trunk .... and more reliable.
  8. V8 Bob
    Joined: Feb 6, 2007
    Posts: 2,485

    V8 Bob

    Moving the starter solenoid to the trunk, along with the battery, has the advantage of allowing the long positive starter battery cable to only be "hot" during starting. A side benefit is the ability to now fuse all circuits fed by 8 gauge or larger wire, depending on system amperage requirements, running from the battery, through a 100 amp (or larger) fuse or fusible link, to a power distribution point. I got the idea from Mark Hamilton (link below) and, although intended for racing, makes sense for the street, IMO. :)
    Last edited: Jun 20, 2013
  9. Kerrynzl
    Joined: Jun 20, 2010
    Posts: 2,284


    I think the opposite [ being a Road-Racer ] and prefer the solenoid near the battery so the main cable is usually dead.

    I run a separate wire to a master switch [ mandatory ] and this also has the charge system.

    It is only for safety in a race car. [plus it is easier to work on without pulling the battery ]

    If you want a "Cheap" source of a quality battery cable, go to the local "U-Pull" and get the cable out of a BMW E36 [ 91-98 3 series ]
    They all have a trunk mounted battery [except hatchbacks ]
    plus they have a neat little junction box you can hook jumper cables to

  10. I have the solenoid under in the engine compartment. I feel like it is a shorter run for the charging circuit. Also I got my cable from a welding supply shop
  11. I see someone else reccomended welding cable, I also use the fine strand. A good crimp is critical.
  12. Bounder
    Joined: Oct 31, 2011
    Posts: 249


    I hadn't thought about this, glad somebody asked. The battery is going in the trunk but hadn't thought about the solenoid.
  13. I keep it simple, solenoid on the fenderwell or firewall. I make up my own cables to fit what I got. I started doing this on my stock cars, Ford solenoids with a GM starter and this has spilled over to my other projects.

  14. Crimp AND solder ... that's the ticket!
  15. Don's Hot Rods
    Joined: Oct 7, 2005
    Posts: 8,319

    Don's Hot Rods
    from florida

    As was mentioned, having the solenoid right near the battery in the trunk kills the current flow to the cable so there is no way of it shorting out and causing a problem. Also, you do not need welding cable, that is way overkill. Go with battery cable of about a number 2 size and you will have all the current you need. You can buy it at any marine store by the foot.

  16. d2_willys
    Joined: Sep 8, 2007
    Posts: 4,094

    from Kansas

    Both ways are acceptable, as long as the ground return from engine block to - of battery is just as strong.

    My feeling is: Have the Solenoid up on front end where you can use the battery post (on solenoid) for connecting the remaining "always hot" cabling. If in back, you will be running another big (10 gauge at least) wire up to front/dash/etc.
  17. Doctor Detroit
    Joined: Aug 12, 2010
    Posts: 1,004

    Doctor Detroit

    Thank you for all the good information to consider. I've had a chance to read through these and think about it for a while. I need more advice please.

    If I decide to put the starter solenoid up front, I have two options:

    Option 1: Inside the vehicle behind the dash, probably behind the glovebox.

    Option 2: Inside the engine compartment, on passenger inner fender (near the starter which is also on passenger side).

    Option 3: Starter solenoid not up front, but in trunk next to battery.

    I'd prefer to go with Option 1, and have the starter solenoid behind the dash, so it's not seen. Would this be considered dangerous to have the 1/0 cables (from the battery to solenoid, and from solenoid to the starter) routed inside the vehicle?

    If I go with Option 2, should I route the 1/0 cables inside the boxed frame rail, so it stays outside the passenger compartment?

    I'm open to all input. Thank you again, in advance.

  18. tfeverfred
    Joined: Nov 11, 2006
    Posts: 15,796


    When possible, I like the simple, tried and true method. I'd keep the solenoid up front, where it belongs. Moving the battery would be okay, just as long as the cable is heavy enough for the length needed.

  19. d2_willys
    Joined: Sep 8, 2007
    Posts: 4,094

    from Kansas

    I vote for option 2, using stranded 2 gauge or 0 gauge wire inside some of that convoluted tubing. Then you can run in the frame with less chances of a short.
  20. Another vote for option 2. I have a fear of large gauge cables INSIDE the cabin. Also, you won't have to run the start wire and "I" wire to coil + (if used) nearly as far.

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