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Called dealer about a dual battery install...

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by steved, May 4, 2013.

  1. SurrealOne

    SurrealOne Former Member ROTM Winner 1000 Posts

    There ya go, [MENTION=54243]steved[/MENTION]. Your application doesn't call for an isolator, I take it?
  2. steved

    steved Former Member


    My application doesn't need an isolator, the truck will be running whenever the winch would be running. I don't sit with the ignition off for very long anyway.
  3. GATUC

    GATUC New Member

    I'm "confused". I have a 2012 Silverado, 1500, 5.3L gas. Putting a 12,000LB winch on it with 6.6HP motor. I have the factory "empty" battery tray. I feel I "should" put a second battery on it. Many places say put an isolator on it, many places say no need???? I feel like steved here, don't need an isolator, but then some places state it may over work your alternator not doing so??? What's a person to do??? I do not have a clue???? Please help....
  4. Pikey

    Pikey Moderator Staff Member 2 Years ROTM Winner 1000 Posts

    I don't think that it would "overwork" the alt. Basically the alternator is just going to keep both batteries charged. If you are not killing the battery now with one battery (because the alt can not keep it charged) then I highly doubt that there would be any damage from 2 batteries. Actually, I would think that it would prolong your alt life, as when you need more power there is another source and the alternator does not need to run at max production to keep up with your needs. Sure, if somehow you killed both batteries and attempted to use the alternator to charge them both at the same time, then you may have an issue. But, even with one battery it is never a good idea to recharge a dead battery with your alternator. An alternator is meant to maintain your battery charge, not recharge a dead battery. I believe that an isolator is always a good idea. I just like the fact the you can tailgate/ party with the radio on (or multiple things charging) and the truck off for hours, you run off of one battery. Lets say that that battery completely dies. You always have the other battery at full charge to restart the truck and get you home. You get home, recharge the dead battery and all is good. This is just my opinion, I am sure others will chime in.
  5. j cat

    j cat Rockstar 4 Years 1000 Posts

    if the battery is discharged the alternator can only pump into the battery about 15 amps when the temp is about 70degf...with 2 batteries dead the alternator will need to produce 30 amps for the batteries. then you add on about 60 amps for the other stuff... so that comes to 90 amps. that would be the worst case ...

    2 batteries actually reduce alternator power surges from these motor winches or more commonly from high power sound generators ...they act as a capacitor to reduce current power surges that can damage the alternator .
  6. WorthFlorida

    WorthFlorida Member 2 Years 100 Posts

    Better check this out http://en.wikipedia.org/wiki/Battery_isolator

    I have the same truck and the second tray does look inviting to use it. The biggest problem you can have is if one of the batteries dies. In the heat of Florida, most batteries have a instant death because one cell shorts out. Up north it's usually a slow death in cold weather. Should one battery have a short it is now below 10 volts and the starter motor will never spin. With a second battery in parallel the voltage difference will drain the good battery and the current flow will reverse. Depending how the battery died it can draw a lot of current from the good battery. The cables between them will get warm and maybe hot enough to melt the insulation. An isolator sure makes sense because it can cost you dollars later on. You might stop by a Chevy/GMC dealer and see if there are any duramax trucks around and look at the battery setup. I kind of doubt both batteries are in parallel. Maybe ask a dealer mechanic who is trained on duramax engines.
  7. j cat

    j cat Rockstar 4 Years 1000 Posts

    batteries fail in many ways. cells shorting out will occur in any climate. normally these failures show up when the extreme heat/cold arrive. this is when the cell short shows itself. the other common failure is when a battery will internally open due to defective design or not being properly secured/handled. this is where the battery output will show a good reading of 12.5 volts , but when a load is placed on it the volts drops out.

    with the newer trucks the battery mounted on the fire wall is not what I recommend. this is an area of excessive heat. in a hot climate I would move this to the front of the vehicle.

    I usually get 7 years out of my vehicle batteries. I keep them clean and insure they are covered on top with a rubber shield to protect from corrosives ...

    The isolator diodes are a great upgrade with 2 batteries but , as long as both batteries are matched and of the same age this should not be required . you must use large guage wire than OEM with 2 batteries. I would also install a fuse between them and cover the cables with a proetctive loom material.
  8. WorthFlorida

    WorthFlorida Member 2 Years 100 Posts

    I'm living 23 years in South Florida and have replaced many batteries including my two son's vehicles. From when I got my first car in 1971 I lived in Upstate NY and Illinois, very cold winters. I learned that if the car battery is 5 years old, good or bad, I would replaced them. Not starting once or twice when it was 0 degrees in the morning was no fun or the wife would call you while you're at work that the car won't and has the kids. AAA or not always a hassle. For the most part I rarely had a battery die prematurely. Florida heat is another story, On average it seems like it's three years and your doomed. I once had a battery die while I was moving it off a set of ramps to change the oil. Just bam, its dead and a hard short it is still difficult to jump start. I did have one go about 4 years, an OEM on a Highlander and it was a slow death so before the wife was stuck i changed it out. I've bought cheap and high price batteries and there seems to be no difference in the heat. I liked Autozone batteries because you can go to any store, they'll find your sales record when the battery was purchased and easily pro rate it. IF you buy a six year warranty battery, it almost guaranteed that you get a new battery with a prorated adjustment. This did happened on the replacement one for the Highlander.

    One year ago I got my new truck, picked it up on Monday and by Thursday the battery went bad. The dealer did
    replaced it. My luck it was one of the millions of good batteries that GM buys and mine the bad out of the box.
  9. j cat

    j cat Rockstar 4 Years 1000 Posts

    very surprised with your battery failure rate. I get 6-7 years out of the oem new vehicle battery AC DELCO...then I got some walmart batteries with 900CCA and thats what I got now in the 2000 silverado. this is the only replacement purchased so far, looks like I am due to replace this as , it is going on the 7th year now.

    back in the ancient history of my life I only got 3-4 years out of my batteries. 3 starter motors in 110,000 miles. this was a 1967 olds. that vehicle took just too much cranking from day one [NEW] on a cold start . after that vehicle , I have had no starter of battery problems with short life failures....

    I do not recommend the sears die hard batteries. they internally open ... so that means suddenly you get nothing . over priced also.

    my 1983 17 years 3 batteries total I purchased 2 . had to replace the starter at 15 years. 380,000 miles when sold .

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