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Dual batteries with isolator and 1 alternator

Discussion in 'The Garage' started by dhcomp, Mar 20, 2005.

  1. dhcomp

    dhcomp 3/4 ton status Premium Member

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    Hey y'all

    I travel a lot in my truck, and will be sleeping in it at a few tournaments i have to go to this year. Problem is, i now have to run a CPAP machine off the battery all night (for sleep apnea). THe machine only draws 2.4 amps, 50-60hz of 120V power, but i really don't want to run this off my battery all night through an inverter and end up with a dead battery. So i think i am going to get a 2nd battery (optima?) with an isolator. Who's running 2 batteries with 1 stock alternator? Does it put a lot of stress on the alternator, or just make it take longer to charge? I'm not drawing any large amount of current (like extra lights or a winch), so could i get away with this setup?

    If so, who's got the best isolator out there? I want both batteries to charge, 1 to run everything, and 1 on reserve for jump starting myself. I remember looking into the hellroaring products on in the past that was on ORC, whats everyone's opinion on that?

    And for a second battery try, i know this was just disucssed, but ive got a 94. What trucks of my era came with a 2nd battery that i could try to get a tray out of? Preferably i'll get a new tray that will just bolt in, where could i get one like this for my "newer" truck? Currently my tray is just behind the grill on the passenger side.

    Thanks, sorry about the long post!
     
  2. 3 on the tree

    3 on the tree 1/2 ton status

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    My understanding is that the bigger the alternator, the less stress charging. My ambulance has 2 batts, 2 solenoids, selection switch for no batt, batt 1, batt 2, or both. Also have 165amp alternator, and about 100 miles of wiring under the hood!! Also have sep volt gauges for each battery. From what I have seen, emergency vehicles have better components than normal aftermarket, course they also cost more. Just my 2 bits.
     
  3. MTMike

    MTMike 1/2 ton status

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    I've got a Hellroaring setup thats' waiting for warmer weather to be installed. I can't wait to use it, but the website should have alot of information on it to answer your questions.
     
  4. BIG*RED

    BIG*RED 1/2 ton status

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    i use the painless wireing waterproof dual battery set up. with two optima batteries and a 94amp alt..it was a breeze to install took about 30 to 45 min. and works great. i have never had any problems. it has a three way switch so you can charge only the main battery, or charge both batteries, and the third position connects the two batteries and alows you to jump start yourself if the main battery gets drained..the only down side to that is, i quit carying jumper cables because all i have to do is flick the switch and i have come across several people needing a jump and i can't help them because they don't have cables eaither...hmm ...so i guess thats a down side for them, not me:D
     
  5. dhcomp

    dhcomp 3/4 ton status Premium Member

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    Ok, so what would be the advantage/disadvantages of the painless vs. the hellroaring? I realize the hellroaring is automatic charge, and the painless is not, but what benefits do each have?

    The painless site says teh middle position connects the 2nd battery when teh ignition is off.....im guessing that means that it charges and draws from teh 2nd when the igniton is on? Will that allow both batteries to charge fully, or what?

    Also, how does the factory gauge behave with a 2 battery setup? Like, is there a way to get a reading on each battery, or what?

    Sorry to keep asking questions, im in finals and having a hard time thinking this out correcty......
     
  6. BIG*RED

    BIG*RED 1/2 ton status

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    on the painless, two of the positions on the three position switch require the ignition to be on, but the second position will work with out the key even being in the ignition. thats the position that connects the two batteries together to jump start. from what i was told, this is mainly for computer contorled vechicles that need power to start the vechile...so you flip the switch power up the main battery and computer than you can start..but since my k-5 doesn't have a computer it doesn't really matter..the kit has two led lights also, one red one green..when no lights are on your chargeing only the main battery, when the green light is on, your chargeing both batteries, when the red light is on, both batteries are hooked together(for jump starting or extra umph for really cold weather starts)

    as for the guage its only conected to the main battery so there is no change or affect on the guage, you will have to buy another aftermarket battery guage if you want one on the second battery...personally i don't have one..i charge it probably every other time i drive..its a n optima so i don't worry about it..but someday i might get the second guage..

    as for the hellroaring...i couldn't tell you, i honestly never heard of them before this post..i can just say that i'm very happy and satisfied with the painless kit i have..
    hope this helps
     
  7. dhcomp

    dhcomp 3/4 ton status Premium Member

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    Ok, thanks a lot, great info! What did the painless one cost you and where can you buy them?

    Also, for everyone....are there different sizes/cranking amp ratings on teh optimas, or are they all the same? My 2nd battery will defitely be an optima. Which is hte deep cycle, red or yellow? I want the non-deep cycle one.
     
  8. BIG*RED

    BIG*RED 1/2 ton status

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    sorry don't remember what i paid for it, but i bought it a summit racing..i live about an hour and a half from their reno store..it was less than 200 bucks if i remember right
     
  9. RootBreaker

    RootBreaker 3/4 ton status Premium Member

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    I just looked... as I have just put a second battery tray in... im going to do a 140 amp alt upgrade.. and want dual batteries... the painless is like $180 plus shipping :blush:

    I mainly just want the second battery to run a winch off of... that is it....
    I wonder if I could just use the setup that chevies with dual batteries in diesels run??? I saw a isolator at pepboys for $50.. more in my budget
     
  10. kgblazerfive

    kgblazerfive keymaster Premium Member GMOTM Winner

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    The isolator from Pep Boys works fine and if your cheap or poor like me and can do some wiring thats the way to go. I hooked mine up so that the second batt only worked when trying to start the truck and had like the off road lites hooked to it also. The isolator charged them both at once.
     
  11. RootBreaker

    RootBreaker 3/4 ton status Premium Member

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    so basically the isolator allows both to be charged... and run say a fuseblock off of that battery (if you wanted to) for lights and winch? that is it???? seems easier than I thought
     
  12. ntsqd

    ntsqd 1/2 ton status

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    I've been down the isolator route in the past. Can't say I recommend it. Isolators have a voltage drop across them. That means that unless the voltage regulator is tweeked for charging thru an isolator that the batteries never get a full charge. I understand some of the later isolators designed for late models have a voltage sense terminal on them. I'm not sure how you can wire this to your benefit w/o the late model alternator.

    I'm not a big fan of the added complexity of the Painless or Hellroaring systems, but for the purpose of the original post I think they would work fine.
    So would a constant duty solenoid. Second battery is connected when the IGN is on and disconnected when the IGN is off. Cole-Hersee makes them. Look a little like a Ford starter relay, except for the all metal case.
     
  13. MTMike

    MTMike 1/2 ton status

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    The Hellroaring ones are solid state and don't have a voltage drop, and it automatically charges both batteries
     
  14. CyberSniper

    CyberSniper 1/2 ton status Premium Member

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    I use a cheap schottkey diode setup that costs about $30. 100amps or so. Can't winch off it but it'll keep the second battery charged at about .62v less than the alternator puts out. I run the diode so if one battery dies I can jumpstart myself.

    The other option is to run a continuous duty solenoid that connects the two batteries when the ignition switch is in the "on" position.
     
  15. RootBreaker

    RootBreaker 3/4 ton status Premium Member

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    will that work with a winch?
    my goal is to have a winch and not touch the second battery.. but would be nice if I stalled...and almost out of the hole.. to flick a switch to use the main battery to get me out the last little bit if I drained the alternate battery....
     
  16. BIG*RED

    BIG*RED 1/2 ton status

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    with the painless kit i run everthing off of the second battery except for the starter.. off road lights, trailer brakes..etc...works fine..as for the "added complexity" of the painless or hellroaring..not sure what he ment, theres nothing complex about it. it hooks up in no time, the hardest part is running the cables nice and neat..and you never have to give it another thought after that..need to charge the second battery, flip the switch, need more power, flip the switch..eaither way you go running a dual battery set up off of one altenator will be fine, as long as the altenator is good...i wouldn't do it off of a stock alt but up grade and youll be fine..there are alot of choices i have seen guys running 120 plus alts, i have a 94amp..got it at kragen for the same price as the stock 64amp..and its more than plenty for me...
     
  17. MarcS

    MarcS 1/2 ton status

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    I agree diodes suck !!!!! Constant duty solenoids the way to go.

    Save your money for other things. The solenoid on the + of the 2nd batt isolates it or connects it to the 1st for more power (winches and other accessories) or jump starting. Isolaters/combiners just do the same thing automatically. If you wire the solenoids coil to 12 V that comes on when you turn the key, it connects both batts together when running, charges both of them and isolates them when you shut the engine off. Then if you also wire a switch to the solenoid and to a constant 12 V source OFF YOUR ISOLATED BATTERY ( like in the Painless kit,but a single switch), you can manually jump the batteries to jump start yourself. How about that ! Just saved about 100 bucks !!!

    As for alternators, Higher current couldnt hurt. I seen 55 amp alternators handle 2 batteries just fine.

    I have this setup on my boat for 15 years and it never left me stranded. You should use a deep cycle battery in your current battery holder because the truck is wired to run everything off this battery. The second battery is isolated and used for starting up the engine. NOTHING should run off the second battery or you will lose your isolation from the rest of the trucks wiring.
    Having a deep cycle and a regular starting battery will not hurt your alternator !!!! This has been used on boats for years (Longer than most of you have been alive) with no problems.

    Sometimes the poormans way is better...:grin:
     
  18. roamingaz

    roamingaz Newbie

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    I used the painless wireing dual battery isolator,two optimas and just installed a 100 amp powermaster 1 wire alt.Works great
    I run a Engel fridge and a 1000 watt power inverter while camping never had any problems.
     
  19. dhcomp

    dhcomp 3/4 ton status Premium Member

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    Ok, thanks guys! I think i'll probably go with the painless kit in a coulpe weeks. If i don't wheel my truck very often, do you think i could get by wiht the non-marine version?

    For the time being, i think i'm just going to run this machine off an inverter/battery combo, not hooked up to my truck (at least until i get back to davis and can install the isolator).

    I don't have to battery charger to charge the battery once i run it down, is there a way to charge it off my truck with jumper cables? What im thinking is like charge it while my truck is idleing, and hook it up to the other battery to charge the same way as i would with an isolator. Does this make sense? If i remember correctly, i would just need to connect the dead battery to mine in parallel with the jumper cables?

    Can anyone confirm this? or am i just going crazy?


    Thanks guys!
     
  20. Habez

    Habez Registered Member

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    Also another question I have somewhat on this topic. Where does everyone have the aux battery? And how did you mount it. I'm working on a dual battery setup and trying to figure out an easy way to do it. Thanks
     

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