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Dual batteries: Isolate or not to isolate?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by txbartman, Jul 23, 2001.

  1. txbartman

    txbartman 1/2 ton status

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    I have installed a lot of lights on my truck. Now I plan to install dual batteries. It isn't that I will ever use all my lights at once and drain my battery (as I also have a 180A alternator). I am mainly putting dual batteries for the added comfort of knowing I am safe when I am a long way away from a jump (whether that is 20 miles offroad or in a parking lot at midnight on the wrong side of town) and to add capacity for a winch that I may add later.

    Now my question, I have the choice of either installing the batteries in parallel all the time or use an isolator (one by Hellroaring or Wrangler NW). I know that using an isolator is really the only way to keep one batt from draining the other, but that also adds $160 or so of cost to the setup.

    What would you guys do or have you guys done?

    Brian
    Click to see <a target="_blank" href=http://tx85gmcguy.alloffroad.com> My 85 Jimmy </a>
     
  2. 84_Chevy_K10

    84_Chevy_K10 Banned

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    I've already got the battery tray for the left side, but I refuse to put in another battery until I can afford the isolator.

    Having two batteries on the wrong side of town won't do you any good if one drained the other. Get an isolator.

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     
  3. Burt4x4

    Burt4x4 3/4 ton status

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    Get the Hellraoring setup!! It is WAY cool! I have it and it truly isolates the batts while alowing the alt to keep them both charged. Hellroaring has great service and thier unit is tiny and very easy to install! Oh and get the remote moduale too that way you can monitor your charging system from in your cab!!

    72K5[​IMG]Led Zeppelin[​IMG]Rock ON![​IMG]
    <a target="_blank" href=http://www.geocities.com/baja/5099>www.geocities.com/baja/5099</a>
     
  4. woody9

    woody9 1/2 ton status

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    You might want to check with a camper/rv dealer. They're into the dual battery setup as well, but don't remember them being quite that expensive...
     
  5. txbartman

    txbartman 1/2 ton status

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    My memory of most RV setups is that the engine runs off battery A all the time. The coach runs off of battery B all the time (or sometimes two batteries in parallel for the bigger RVs). There is a switch that can be flipped that essentially jumps the engine or chassis battery from the coach batteries. But you could never combine them for use. I expect to run my engine off of battery A and probably my high power accessories (lights) off battery B. But, if I add a winch later, I would want to run the two in parallel for the amperage. And I believe in only building things once. I will probably go with the Hellroaring.

    Brian
    Click to see <a target="_blank" href=http://tx85gmcguy.alloffroad.com> My 85 Jimmy </a>
     
  6. CaptCrunch

    CaptCrunch 1/2 ton status

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    Burt4x4- How much did that setup run you? What batteries are you running? Thanks

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
    <a target="_blank" href=http://www.geocities.com/milnerlives_2000/blazer.htm>http://www.geocities.com/milnerlives_2000/blazer.htm</a>
     
  7. bart

    bart Registered Member

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    The factory dual battery setups in GM vehicles had the batteries connected in parallel. You can do this, although you will have to replace the batteries in a set...and they have to be identical, otherwise one will become weak if they are mismatched. Is there a downside?, yes, you can run both down simulatenously...is an isolator worth it? It depends on how much you have to spend. For adding more reserve capacity (and ampacity), a parallel setup will do just fine, just stay on top of maintenance (electrolyte level, if serviceable).

    bart
     
  8. RESTORE89

    RESTORE89 1/2 ton status

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    check with a local marine dealer or http://www.ritzcamera.com/cgi-bin/n...0wOyJ9WtwOUShdQxpEmn3UIrFLexG6lZydcyv7oO11/E=
    that is the longest web address i have ever seen, but it is at boaters world for battery switches, and we use them on offshore boats all the time to do just what you are suggesting, and it sound a lot cheaper. that is the first time ever that something for a boat is cheaper than for a car


    It needs a bigger motor.
    what's in it now?
    doen't matter it NEEDS A BIGGER MOTOR
    89 350tbi/700r4h/np208/4.11's
     
  9. pcorssmit

    pcorssmit 1/2 ton status

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    I run a starting battery on the pass side for the starter, ignition, fuel pump, computer, winch etc. Everything else runs off a deep cycle battery on the drivers side. They are hooked together with a continuous duty solenoid (~$20 at NAPA, normally used for RVs), which is switched in the cab and normally is engaged when running. This way I can run the stereo and lights all night until the batt. is dead, and still fire right up in the morning. Has worked well for 4 years now.

    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     
  10. txbartman

    txbartman 1/2 ton status

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    What does the continuous duty solenoid do for you? And how do you have them hooked up? My primary chassis battery is connected to ground and to my starter. The alternator is also connected to the same place on the starter. Where in this would you put the solenoid? And how do you have the switch done? Can you automatically jump the chassis battery with the auxillary battery? Or do you have to manually do it?

    Brian
    Click to see <a target="_blank" href=http://tx85gmcguy.alloffroad.com> My 85 Jimmy </a>
     
  11. pcorssmit

    pcorssmit 1/2 ton status

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    The continuous duty solenoid is on a 4 gauge wire running between the pos. terminals of the two batteries. The alternator is hooked to the starting battery. Both batteries are grounded to the chassis and block. The solenoid allows for connecting the batteries when running to charge the deep cycle, then disconnecting them when stopped to avoid draining the starting batt. with the accesories. The trigger for the solenoid is hooked to a dash mounted switch that only has power when the ign. is in run and start. A better way would be to use a center off toggle, so that when the switch is left, it would have power in run only, center it would be off, and right it would have power in run.

    Pete

    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     
  12. txbartman

    txbartman 1/2 ton status

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    Thanks for the info. By using the 3 position toggle, I could jump the chassis battery from the deep cycle battery if the chassis went dead. One more question, if I connected one side of the solenoid to the deep cycle and the other side to the chassis battery and the alternator, would I allow a charge of the deep cycle battery from the alternator without passing as much current through the chassis battery? Does that make sense? Or should I leave my alternator hooked directly to the chassis battery and have the deep cycle charge from the alternator thourgh the chassis battery?

    Brian
    Click to see <a target="_blank" href=http://tx85gmcguy.alloffroad.com> My 85 Jimmy </a>
     
  13. BurbinOR

    BurbinOR 3/4 ton status

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    Since I live about a half hour from WranglerNW, I would prefer to give them the local business, but have a couple of questions. Do they have an in-cab system status check as Hellroaring does, as well as the ability to switch between batteries from inside? Cost for your whole system? PM me if you want on the price thing. Dual Batteries is the next mod for me..........

    <font color=blue>'79 ONE TON TPI K5 - See it at---&gt;<a target="_blank" href=http://www.blazzinor.alloffroad.com>www.blazzinor.alloffroad.com</a>
     
  14. 84_Chevy_K10

    84_Chevy_K10 Banned

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    It wouldn't put as much charge in the chassis battery because current takes the path of least resistance--in other words, from the alternator, through he wire and solenoid, then to the auxilary battery.

    That setup seems to work, but I'm not putting in another battery until I can afford to truely isolate them.

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     
  15. pcorssmit

    pcorssmit 1/2 ton status

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    Hmm, sounds (functionally) like the same thing I described above with the center-off toggle. For about $150-$175 more.

    Pete

    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     
  16. txbartman

    txbartman 1/2 ton status

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    I bought a 160A continuous duty solenoid from a local parts shop yesterday for $35. I am going to get the 3-position switch today ro tomorrow and the rest of the wiring next week. I will take lots of pictures as I do it and do a write up including all costs, in case someone else is interested.

    Brian
    Click to see <a target="_blank" href=http://tx85gmcguy.alloffroad.com> My 85 Jimmy </a>
     
  17. BobK

    BobK 1/2 ton status

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    I vote for Hellroaring.It's an excellent product with excellent tech. and customer support.Price is approx.$145.00 +$35.00 for the incab remote.I have one and it works real well.I just put in a dual electric fan setup in my 71 Blazer and the Hellroaring unit alerted me that my charging system wasn't putting out enough juice now.

    <font color=green>BobK<font color=green>
    <a target="_blank" href=http://www.zing.com/picture/p8947726813026de684f60e0bd6f3fbfe/fe8f5839.jpg>http://www.zing.com/picture/p8947726813026de684f60e0bd6f3fbfe/fe8f5839.jpg</a>
     
  18. WOODYJ

    WOODYJ 1/2 ton status

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    I would definitely isolate. If one battery goes down the other will be down also if not isolated.
    Pros of Isolation:
    Have both batteries charging all the time so should have one up at all times.
    Cons:
    You will be charging both batterries all the time and if you are just running off one, could boil all the water out and burn up the battery. Did that once in my wheelchair accessible van. Not a pretty sight!!

    k5woody I Don't Understand The Jeep Thing Either!!!
     
  19. txbartman

    txbartman 1/2 ton status

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    Wouldn't a auto-sensing alternator prevent this?

    Brian
    Click to see <a target="_blank" href=http://tx85gmcguy.alloffroad.com> My 85 Jimmy </a>
     
  20. pcorssmit

    pcorssmit 1/2 ton status

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    I'm a cheap bastard. Gotta save up for those 35 spline outers so I can get back on the trail (maybe I'll strike it rich and get a new tranny, then I can get back on the road!).

    Pete

    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     

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