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2nd battery

Discussion in 'Early CJ5 and CJ6 Tech' started by chuck123wapati, Mar 7, 2010.

  1. Mar 7, 2010
    chuck123wapati

    chuck123wapati Member

    wyoming
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    Jun 18, 2008
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    761
    Where is a good place to put another battery, with 4 extra lights and a winch I could sure use one.
     
  2. Mar 7, 2010
    EricM

    EricM Active Member

    Southern California
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    What size alternator are you running?
     
  3. Mar 7, 2010
    Eaallred

    Eaallred Member

    West Valley City, UT
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    Oct 9, 2008
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    Agreed. A good alternator and a good battery is usually all you need.

    Assuming you will use the lights with the engine running, an alternator is what you need here, not a battery.

    Extended winching could use a second battery, but a good alternator with a good battery will work for most everyone.

    A Delco 10si alternator puts out 63 amps. May not seem like a huge number, but consider the formula for amperage, and it will keep up with most guys needs.

    volt x watt = amp.

    By the math, if you max out the 10si alternator, you can put out 882 watts of power at 14 volts, 850 watts at 13.5 volts, and 819 watts at 13 volts. That's a LOT of power, especially when it comes to lighting.

    Between my high beams and my 100 watt aux lights i'm pushing 320 watts of light out the front of my CJ. With this load, my voltage is at about 14 volts. Meaning i'm only using about 23 amps of power. Just over 1/3 of what my alternator is capable of. Plenty of room to spare to run my heater and taillights.

    Battery recovery time from a long winch pull shouldn't be too bad with 60 amps charging it back up either I would think.
     
  4. Mar 7, 2010
    w3srl

    w3srl Semi-retired in Florida Staff Member

    Port Orange, FL
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    Nov 6, 2002
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    With an early CJ your options are pretty limited, especially with a V6 under the hood.

    Off the top of my head you might look at extending the firewall battery tray to tak etwo batteries side-by-side fore & aft, but you'll probably need to add a brace to the fender or frame to hold the weight. Another less-than-appealing place would be in a battery box in the back of the jeep, strapped firmly to the floor. You can run a ground cble to the frame and then run a nice, thick welding cable up front to power the winch.

    In any case the best way to wire it up is with a big diode isolator in between the batteries, so the single alternator can charge both batteries simultaneously but one run-down battery cannot drain the other. This is how emergency vehicles are wired, as well as motorhomes, etc. You can also add a solenoid and a momentary switch to parallel both batteries in an emergency so you can start the rig if the primary battery goes out on you.

    Sorry I don't have a better answer, but there just isn't much real estate to work with in an ECJ.
     
  5. Mar 7, 2010
    chuck123wapati

    chuck123wapati Member

    wyoming
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    Jun 18, 2008
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    "In any case the best way to wire it up is with a big diode isolator in between the batteries, so the single alternator can charge both batteries simultaneously but one run-down battery cannot drain the other. This is how emergency vehicles are wired, as well as motorhomes, etc. You can also add a solenoid and a momentary switch to parallel both batteries in an emergency so you can start the rig if the primary battery goes out on you.

    Sorry I don't have a better answer, but there just isn't much real estate to work with in an ECJ. "


    This is the problem I can be 20 miles from no one in 30 minutes here. Wyoming is awesome in the fact that it is still pretty wild country. I can go any direction I want and find solitude in less than a mile and Ive seen the time when we've drained the battery with the winch. Just wonderin if anyone had a secret spot that I didnt know about.
     
  6. Mar 7, 2010
    n6ifp

    n6ifp Member 2019 Sponsor

    San Bruno/...
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    Sep 15, 2004
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    My cj5 doesnt have a heater, so I put a spare battery on the drivers side where heater block off plate is. I was able to put a group 24 there. I added a continuos duty solenoid that allows it to charge when motor is running. Larry
     
  7. Mar 7, 2010
    chuck123wapati

    chuck123wapati Member

    wyoming
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    That may be an idea buy an under dash heater and set another battery where the old heater was. That would be cool my wifey needs her heater though.
     
  8. Mar 7, 2010
    Warloch

    Warloch Did you say Flattie??? Staff Member

    Falcon, CO
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    Depending on your setup - I have seen them sunk in the floor in the back between cross members, and under the Pass seat in place of the tool box.

    NW Colorado is alot like WY (Bags was only 48 miles N of where I grew up) so I know what you mean.
     
  9. Mar 7, 2010
    chuck123wapati

    chuck123wapati Member

    wyoming
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  10. Mar 7, 2010
    wheelie

    wheelie beeg dummy 2019 Sponsor

    York, PA
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    I had a custom box made up for 2 batteries. I had it bolted to the floor behind the pass seat. Took up the entire length of the fender well and about 1/3 or so of the width of the bed area. I figured the extra weight in the back would help even out the overall weight distribution. And, sice I generally travel pretty light, I thought the cargo space loss would be acceptible. I took that box out about 2 years ago and put the battery back under the hood and still never have added the second battery. I have seen dual optimas mounted on the firewall of an ECJ5 b ut it sure seems heavy for the firewall. If I didn't have a rear tank, I'd sink 'em into the floor in the back with some sort of smooth access door. As in a prior post, just not much anywhere.
     
  11. Mar 7, 2010
    mdbeck1

    mdbeck1 55 Willys CJ5

    Oklahoma
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    Aug 21, 2008
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    Physics/math update...

    Volt X Amp = Watts
     
  12. Mar 8, 2010
    Eaallred

    Eaallred Member

    West Valley City, UT
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    Good catch, I meant "/"
     
  13. Mar 8, 2010
    Warloch

    Warloch Did you say Flattie??? Staff Member

    Falcon, CO
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  14. Mar 8, 2010
    duffer

    duffer Rodent Power 2019 Sponsor

    Bozeman, MT
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    I put the 3B battery below the floor directly behind the driver's seat. The steel box is hung off both the frame and the cross member. It would have been better on the right side from a weight standpoint, but no room there with the D18.

    [​IMG]
     
  15. Mar 8, 2010
    alex211

    alex211 Member

    Pennsylvania
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    Aug 25, 2009
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    Put a 94 amp delco 12SI on there, it should bolt right up. Get one for a 1985 buick riviera with the 307 and extra options.
     
  16. May 3, 2012
    68BuickV6

    68BuickV6 Well-Known Member

    Chino, CA.
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    I know this is a really old thread, but an alternator for a '71 Pontiac GTO 6.6L V8 is rated to 100 amps. Relatively inexpensive, and functions great in my experience.
     
  17. May 3, 2012
    chuck123wapati

    chuck123wapati Member

    wyoming
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    thats what i ended up doing, installing a 100 amp alternator and a new battery
     
  18. May 3, 2012
    jzeber

    jzeber Well-Known Member 2019 Sponsor

    Morgan Hill, Ca
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  19. May 3, 2012
    chuck123wapati

    chuck123wapati Member

    wyoming
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    wow I like that, side by side idea:)
     
  20. May 4, 2012
    jzeber

    jzeber Well-Known Member 2019 Sponsor

    Morgan Hill, Ca
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    Thanks, I used 2 Interstate batteries, really tight fit but it seems to work well so far. Both batteries were rated at around 540 CCA.
    I have a friend that had stalling and starter troubles on the Rubicon at 11:00PM, wore his battery out pretty quick. Decided after that trip to add the 2nd one.
     

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