# Dual Batteries



## canoebuildah (Oct 20, 2007)

I am in the process of setting up a recently purchased 2005 Chevy 2500 Ext Cab 6.0L to run my Blizzard 810. I have been plowing with a 2007 Chevy 3500 that has factory dual batteries. The Blizzard dealer tells me that its can't hurt to have a second battery, my mechanic tells me it is unnecessary. 

I plan on running the plow, a LED amber roof light and a set of 55w backup lights. I have no plans at all in adding anything else like a sander.

Do I "need" the 2nd battery? Or can I just get the largest battery available? When we bought the truck last month, the battery was pretty weak and swollen. I borrowed a battery from one of our Chevy vans that we store for winter. So I am going to buy a new battery anyway before the plow is installed next week.

I am trying to keep costs down in this economy so I don't want to spend the money on a 2nd battery install if I don't have to.


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## 06Sierra (Nov 30, 2008)

I have an 06 1500 GMC. I bought a Die Hard Platinum last fall and did the "big 3" upgrade on the power and ground wires. So far I haven't had any troubles. Lights still dim a little when operating the plow, but not as bad as they did.


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## RichG53 (Sep 16, 2008)

Dual Battery Install Instructions for a Chevy
Please make this a Sticky Forum Mod..

This is compliments of B&B.
Here is a complete install instructions for all of you trying to hook up dual batteries. Good Luck.....

The battery tray is a easy to add, you just use the factory aux battery tray from GM and it will bolt into the stock location just like GM intented.. The tray is mounted on the pass side inner fender between the coolant tank and the firewall. You will need to remove the upper curved fender brace between the fender and the firewall to provide the clearance for the battery but it won't affect the structural integrity of the fender. Depending on the physical size of the battery you going to mount in the tray, you may need to trim the tab off the firewall where the fender brace was mounted that you just removed. A quick zip with an air saw or even tin snips will remove it easily. Use a file and a little touch up paint on the cut edge to dress it up a bit.

The part numbers you need to get from the dealer are:
Support: 15705102
Screw: 11509853
Clamp: 356668

The easiest way to wire duel batteries to the 99-up Silverados is to use batteries that have top and side terminals both. By having top and side terminals both, you can just leave your stock cables the way they are and use the top posts for all your additional connections. I like to use a set of top post terminals like these here: http://www.sonicelectronix.com/item_...y+Terminal.htm I just provided the link so you'd know what to look for since you can buy them at a local store like NAPA or AutoZone or most any stereo shop. I also like the fact that these terminals are gold plated so they last a lot longer as far as corrosion goes.These style terminals make this a super easy job because if you look closely at the pic, they have ports in them that you just strip the insulation off the cable and insert it into the port in the terminal.They have an Allen set screw in them to tighten the cable. That way you don't need to crimp any cables. I do recommend adding a little solder to the stripped end of the cable though so the Allen screw doesn't crush the cable and will add additional contact surface. Just buy enough cable to reach from one battery to the other how ever you want to route them around the engine compartment and simply connect the positive on one battery to the positive of the other battery terminal. Do the same thing on the negative side too.

Three other things that I would recommend doing at this time:

1) Upgrade the charging wire on the back of the alternator to a 4 gage cable as this is a weak link on the GM trucks. Leave the stock one in place but add a second one from the charging stud (where the original wire is on the alternator) directly to the positive on either battery (driver side would be closer).

2) Add an extra ground cable from the aux battery to the frame, and one from the frame to the engine.

For these 3 cables you can just buy a replacement universal battery cable with an eye on one end. Then you can just cut the other end off (doesn't even matter what kind of end is on this side as your cutting it off anyway) and insert it into your gold plated terminal.

Make sure both the power and ground cables for the plow are connected directly to a battery. Do not connect them to the factory pos junction block near the power steering pump or connect the ground anywhere but the battery. This will allow a clean voltage path directly from the batteries to the plow where it's need the most.

That's why these gold plated "port" style battery terminals are so handy, since they're easy to add extra cables to and they still look clean and neat with good conductivity.

You want to use 2 gage cable for all these wiring upgrades (except the new alternator wire, use 4 gage like mentioned)

Adding the duel batteries connected directly togethter and upgrading the stock charging wire and ground cables will allow the system to operate at peak efficiency and allow the alternator to provide all the amperage it can to keep the batteries charged.


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## mkwl (Jan 21, 2005)

I have a single Optima yellowtop battery in my truck- have been plowing with a single with no issues (knock on wood)- I think you'd be fine with a single- just make sure it's a deep cycle (like an Optima yellow)- they're expensive but worth it!


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## mayhem (Aug 25, 2006)

Been wanting to do the dual battery update for a couple years. I get dips in my lights when i run my plow electrics, but I've never had a lack of available charge. I do need to do the big 3 upgrade though, whihc should help my issue. 

Long term I'm planning on adding things like an aftermakret stereo with an amp ro two, so the extra juice will be nice.

For your application, i woudl ask what are you plowing and for how long? If you have a route where you are moving your plow and running the electrics alot you mgiht benefit from a second battery, but if you've got a route that is fairly simple you amy not have a need.


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## Burkartsplow (Nov 1, 2007)

I have duals and I just like the piece of mind. been running them all my trucks or years.


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## BigLou80 (Feb 25, 2008)

my local dealer told me it wouldn't make a difference and not to waste the money, My lights would get really dim and I never had an alternator last more then a year

I installed duals anyhow, now my lights don't dim and this alternator is 2 years old


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## ABES (Jun 10, 2007)

I have a new single 770 CCA Napa legend battery with a stock 105 amp alternator and the lights dim a bit and the blower motor slows but its not that bad. I may upgrade the alternator to a 140 amp just for the piece of mind I have no idea if its original or not. I would hate to lose it in the middle of the storm.


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## cr252many (Mar 7, 2007)

I put a second battery in line for my rear blade, it has made a difference. Even with a HD alternator I used to get dimming lights when I hit either front or rear plow. Now the dimming is all but gone and the rear blade runs much faster. It is the lack of amps that is the enemy here!


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## WRIGHTWAY (Nov 17, 2005)

Never had any problems with one but when the rear plow was added 2nd battery was added


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## Sydenstricker Landscaping (Dec 17, 2006)

What the heck is the "big 3" upgrade to the wires???


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## RichG53 (Sep 16, 2008)

Battery to battery-------Alternator to battery--------Ground to frame & Engine....1,2,3......


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## kbsnow (Oct 22, 2009)

Hey guys, where can I buy the longer battery cables to install the dual set-up? I've got 2 identical batteries bought at the same time, and I need the longer cables. Who sells them, and are they expensive?


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## deere615 (Jun 1, 2007)

kbsnow;875669 said:


> Hey guys, where can I buy the longer battery cables to install the dual set-up? I've got 2 identical batteries bought at the same time, and I need the longer cables. Who sells them, and are they expensive?


I had troulbe finding them also. Most auto parts sell cables but they are not long enough. Tractor supply sells it but rather pricey. I ending up usuing some weld led wire my dad had


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## overtime (Nov 5, 2009)

Napa sold them to me I think it was 1.99 ft. At my cost that was 2 gauge


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## kbsnow (Oct 22, 2009)

Thanks "overtime"...I'll check out Napa on Friday


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## overtime (Nov 5, 2009)

Yep no problem. Took me a bit to find out they sold the wires. I needed 9.5 ft each red and black and farm and fleet had red 2 gauge but was like 25 ft and 55 bucks


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## RichG53 (Sep 16, 2008)

I bought mine at Farm & Fleet also I know you have to buy a whole roll but it was my best choice...
Couldn't find it any were else around here...
Now I have extra ....


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## kbsnow (Oct 22, 2009)

I live in Chicago by Midway Airport, so don't have any Farm n Fleet. I have a lot of Napa's so I will check them out.


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## milwaukeevtwin (Nov 2, 2008)

*Welding cable*

Go to a welding store. You can buy it buy the foot. I run 0 gauge and did the big 3 with all of it with a autozone 1,000 amp battery, because i have no other room for another battery. Install a 200 amp alternator and have never looked back. What a hell of an improvement! It was a paint messing with the zero gauge, but it was all worth it. Last year on the coldest days the Jimmy sat out and always had plenty of cranking power I am going to do the same in my other trucks when i have the time.
Thanks, Ron


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## kbsnow (Oct 22, 2009)

ThanksRon...never thought about welding wire. I have a few welding supply stores and will chk thm out on Monday.


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## milwaukeevtwin (Nov 2, 2008)

kbsnow;880478 said:


> ThanksRon...never thought about welding wire. I have a few welding supply stores and will chk thm out on Monday.


The one here in town also carries the ends for the terminals. I tin both ends with solder and then drill a hole in the top and fill them with solder. I have never had one come loose. Works real good. I am glad i could help.
Thanks, Ron


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## kbsnow (Oct 22, 2009)

Dual batteries are installed. Hey Ron, once you mentioned welding wire, before I went to the welding store, I called a friend whose dad works for a place that builds generators and welders. Sure enough, his dad gave me "scrap" 3ga cable and a box of lugs. I'm wired and ready to go.

Thanks,
Ken


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## kbsnow (Oct 22, 2009)

Oh, one more thing Ron, I soldered all the connections. The cable was all black, so I bought a role of red electrical tape and taped the positive cable.


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## deere615 (Jun 1, 2007)

kbsnow;885172 said:


> Oh, one more thing Ron, I soldered all the connections. The cable was all black, so I bought a role of red electrical tape and taped the positive cable.


Yeah mine were both black to I actually spray painted one red and it actually held d up alot better then you think it would


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## milwaukeevtwin (Nov 2, 2008)

*Wire*



kbsnow;885172 said:


> Oh, one more thing Ron, I soldered all the connections. The cable was all black, so I bought a role of red electrical tape and taped the positive cable.


Glad to here that. I you red and black zip ties. It works good. Sounds like you are set.
I hope you have a good year.
Thanks, Ron


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## merrimacmill (Apr 18, 2007)

My second battery in my 2007 NBS Sierra dump truck stopped charging a few hours before a storm making my plow inoperable. There was 11.6 volts at the aux battery (which the plow is hooked into) and there was 14.4 volts at the main battery. So I had to run a long battery cable from the plow solenoid to the main battery and run off one battery for the night. Going into the dealer thursday to find out what the deal is with it.


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## B&B (Nov 4, 2006)

merrimacmill;894498 said:


> My second battery in my 2007 NBS Sierra dump truck stopped charging a few hours before a storm making my plow inoperable. There was 11.6 volts at the aux battery (which the plow is hooked into) and there was 14.4 volts at the main battery. So I had to run a long battery cable from the plow solenoid to the main battery and run off one battery for the night. Going into the dealer thursday to find out what the deal is with it.


Never connect the plow cables to the aux battery on a stock GM dual battery setup. The OEM aux battery relay does not have the capacity and can not handle the large AMP draw of the plow and will die an early death. Get the cables over on the main battery.


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## merrimacmill (Apr 18, 2007)

B&B;894565 said:


> Never connect the plow cables to the aux battery on a stock GM dual battery setup. The OEM aux battery relay does not have the capacity and can not handle the large AMP draw of the plow and will die an early death. Get the cables over on the main battery.


Interesting, that is how the dealer installed the plow. So let me just confirm what batter is actually the aux battery. They had the plow connected to the battery that is on the front drivers side of the engine compartment. I always considered this the main battery, but have now been told the battery in the back passenger side of the engine compartment is actually the main battery. Which is correct?


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## B&B (Nov 4, 2006)

The battery on the drivers side is the main battery.


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## merrimacmill (Apr 18, 2007)

B&B;908954 said:


> The battery on the drivers side is the main battery.


Ok so I guess its my main battery that isn't charging. I just haven't had time to get it to a dealer, I hope its ok through the night with the storm we have coming.


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