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Need help with dual battery?

Discussion in 'Chevy Trucks' started by timtpa, Dec 17, 2010.

  1. timtpa

    timtpa Member
    Messages: 56

    I have a 98' GMC Sierra 2500 and have allways had dual batteries. Over the summer I had a battery issue and pulled the second battery that was newer and put it where the primary battery went and threw away the battery that was bad. I am now only using 1 battery.

    My truck now is getting harder to start and the lights dim when using the plow etc. I def want to put a second battery back in, but am unsure what to get? Could anybody steer me in the right direction as to what I need? I will prob pick one up tomorrow at wal-mart or the auto parts store.
    What size or cranking amps should I go with? Is it ok to go with a ever-strat from wall-mart? My truck already has the 2nd battery tray. I just dont know what is recomended to use as a second battery. I would just check to see what I had in there, but want to put the proper one in! Thank you.
  2. calhoun

    calhoun Senior Member
    Messages: 165

    You need to find out how the 2 batteries are connected to each other. If it is non isolated (TP2) you have to replace both batteries at once with the same size. If not the weak one will draw down the new one.

    If your truck has the isolated option (8B0) you can replace just one, but both would be easier on the charging system.
    If it is the main battery get the highest cca available in your case size. If you are replacing the isolated one you can get a smaller size. The factory isolated set up came with a lower cca isolated battery. If you put that one in the main battery you will notice slower cranking and diming with the plow.

    IMHO I would always replace both with the biggest available cca.
  3. BlizzardBeater

    BlizzardBeater Senior Member
    from Maine
    Messages: 420

    Definatley want to replace both with a good high cca battery, but dont forget about reserve capacity. If you compare the specs on cheaper batteries you're likely to notice differences in reserve capacity. Believe it or not, a better reserve capacity is more important than cca's, especially with high draws like plow motors.
  4. timtpa

    timtpa Member
    Messages: 56

    I popped my hood today and the one battery that I have is on the passenger side and only has 690 cca. The battery tray on driver side is empty. Not sure if this matters? As you have probably noticed, when it comes to trucks im kind of clueless! Thanks for the help and any imput is appreciated! Tim
  5. maverjohn

    maverjohn Senior Member
    Messages: 902

    The store can tell you the right CCA you need for your truck, if you can replace both, remember your wifes car need a battery also.
  6. rcpd34

    rcpd34 Senior Member
    from MD
    Messages: 662

    I buy the biggest battery that will fit. ALWAYS replace them both together with the same battery.
  7. mcwlandscaping

    mcwlandscaping 2000 Club Member
    Messages: 2,557

    Is reserve capacity listed on the battery? Ive never seen it or heard of that and i would be interested to find out what i've been using...how is it measured?
  8. BlizzardBeater

    BlizzardBeater Senior Member
    from Maine
    Messages: 420

    It's measured in Amp/hours. The higher number, the longer the battery will put out its rated amps. While how many amps a battery is putting out may be important when turning over a big motor, it's usually even more important how long it will provide peak power, especially when running heavy draws such as plows and aftermarket lighting systems. Its usually printed somewhere on the sticker, a lot of times in smaller print. More often its printed right under the CCA's. A reserve capacity of 130 amp/hrs with a sufficient CCA rating would do you great.