• If you currently own, previously owned or want to own an Avalanche, we welcome you to become a member today. Membership is FREE, register now!

Anyone Have an Auxiliary Battery?

TheAtheistReverend

Full Member
Joined
Sep 14, 2014
Messages
19
Location
Minneapolis Minnesota
According to the owners manual, there is an option for having an aux battery mounted on the passenger side of the engine compartment  :eek:

I am curious where and how this fits and I'm wondering if anyone here has this feature?
 
Well I have a dual battery setup on my 08. The original location is on the passenger side. They switched locations I think with the new body style. However, the location on the drivers side still has the tray. I believe you just need to order the tray and hold down. Heres a pic of mine:

8944_10154726428740652_4649401011046930941_n.jpg
 
Yup, I have one in my '04. Added the tray, cables and an isolator switch so I can manually turn it on or off.

I don't have any pix of my setup though. There's a lot of guys on here with dual batteries.
 
There are many old threads about auxiliary batteries added to first generation and second generation AVs. Many mention a wiring kit to make the electrical part of install easy, I believe it's called the "Painless wiring kit." In addition to the battery tray and hold down you will have to choose what type of battery to use for backup based on need such as a cranking battery for backup starting or a deep cycle battery for long use by accessories etc.
 
Just finished doing this in my '03.

I used as PAC - 200 solenoid, some 4 gauge wire and a couple 200 amp breakers.

And the already mentioned battery bracket. I had to loose the fender brace in mine.
Mounted the PAC-200 solenoid to the side of the battery bracket. I have a stinger 200 amp circuit breaker I mounted to the top of the firewall and an inline circuit breaker I have wire tied to a major wire harness bundle. You want to fuse the connecting wire near the battery and near your power source to prevent vehicle fires.

For my power source to charge my battery I connected to the red break out box on the drivers side where the alternator connects to the starter cable. For switching on my solenoid I tied into the SEO fuse just to the right and center in the underhood fuse box. I ran the wire for this solenoid inside the main power harness that runs from the under hood box to the top of the engine. I ran this wire under the engine cover and tied it to the wire that runs to the passenger side.

I did this to power my Truck PC and eventually audio system.

I should take some pictures but my setup certainly doesn't look factory.
 
Yes. Added a dual battery to my 06. It's isolated and controlled with ignition. Have a momentary switch in the center console should the primary die, press and hold switch, turn key and truck starts.
 
avalanchedriver said:
Yes. Added a dual battery to my 06. It's isolated and controlled with ignition. Have a momentary switch in the center console should the primary die, press and hold switch, turn key and truck starts.
I was considering doing this but If I need to I can short out the connections I need to do this with my key and hit my auto start so I haven't done this yet.
 
I have added, over the years, two Painless Performance #40102 Battery Switch Systems to vehicles. It is available at JEGS.com

If you go with this system, you will be working with large #1 gauge cables. For that you WILL need the services of an electrician to PROPERLY crimp lugs with a large crimp tool. This tool is not something you would want to buy ($200). An electrician would likely crimp the lugs for you for a few bucks, maybe some beers, etc. DO NOT under any circumstances try to crimp using pliers, vice-grips, hammer, vice, etc. There is high current in the cabling when used and you DO NOT WANT to have poor connections from improper crimps.

The solenoid is mounted to the edge of the battery support plate. I used one hole already existing in the plate, and added a second 1/4" hole.

The 1/8" thick optional plexiglass cover I made and installed prevents a short should a wrench be dropped on the solenoid (from A/C work being done, etc.) It is secured in place using the battery hold-down bolt.

All that being said, if you PM me with a street mailing address I will mail you a very detailed set of instructions that I created. If you follow the instructions step by step the installation is clear, easy and SAFE. The instructions include crimp lug part numbers, cable lengths to be cut, where to attach the ground cable, information about miscellaneous parts, and a drawing for making an optional plexiglass solenoid cover. Also I have made some drawings showing in detail the manual switch setup plus other updates to the Painless Performance documentation. Oh, and I mounted the manual switch and lights on my dashboard, but you can have that under the hood if you so desire. I also added an additional optional analog voltmeter to monitor the new AUXILIARY battery.

Note in the photos there is a large black box with red button mounted on the firewall (to the right of the battery.) This is a 90 AMP circuit breaker for my sound system and it is NOT a part of the Auxiliary Battery System.
 

Attachments

  • AUX Battery 1.jpg
    AUX Battery 1.jpg
    59.1 KB · Views: 151
  • Solenoid And Plexiglass Cover (2).jpg
    Solenoid And Plexiglass Cover (2).jpg
    52.4 KB · Views: 149
  • Spacing Washers Behind Cable Bolts.jpg
    Spacing Washers Behind Cable Bolts.jpg
    53.5 KB · Views: 146
  • Battery Box To Solenoid Cable Routing.jpg
    Battery Box To Solenoid Cable Routing.jpg
    53.9 KB · Views: 145
  • Battery Box With Added Cable At Top Right.jpg
    Battery Box With Added Cable At Top Right.jpg
    52.9 KB · Views: 145
And One More Photo Just For Grins    >:D

The mounting plate that I put in the open cubby was made from a kick panel that I got at the Chevy dealer. (The kick panel is the panel near the floor to the left of the driver's foot, or to the right of the passenger's foot). I cut the dashboard piece from the flattest part of the panel. I forget the cost of the panel but it was not unreasonable, or I would have done something else. The best part is that the panel texture and coloration matches the rest of the interior components.

I also used the old cubby itself as part of this mod, and drilled a hole in the rear of it through which to pass the wiring.

The switch is oriented / wired such, so that when the switch toggle is pushed to the left the RED light is illuminated, and to the right the GREEN light is illuminated. In other words, the lights match the switch position. It is a logical setup that way.

The original colored light bulbs supplied with the kit were replaced for my installation with Radio Shack 12 volt LED's. Part numbers are: RED = 276-084, and GREEN = 276-085.

The meter is a Shurite # S0100108   0-15V DC military ruggedized type analog voltmeter. It is wired to the manual switch and in effect is wired directly across the newly added AUXILIARY battery to monitor its state of charge. I use an OPTIMA redtop battery for the AUXILIARY battery, and I attach NO ACCESSORIES to it. To do so would defeat its intended purpose of being, in reality, AN EMERGENCY BACKUP BATTERY.

As the added AUXILIARY battery is also NOT CONNECTED to the vehicle charging system, I "condition" it once a year with my good battery charger to maintain the battery.
 

Attachments

  • Manual Control Switch And Meter On Dashboard.jpg
    Manual Control Switch And Meter On Dashboard.jpg
    43.6 KB · Views: 145
02 Northface said:
I use an OPTIMA redtop battery for the AUXILIARY battery, and I attach NO ACCESSORIES to it. To do so would defeat its intended purpose.

So what is it's purpose?  ???
 
I would guess to start the truck should the primary die.
 
avalanchedriver said:
I would guess to start the truck should the primary die.

Exactly. It has saved issues for me on two Avalanches. A few very weak, and one suddenly-dead, main battery problems.

A switchable backup battery system is especially valuable to off-roaders, for wilderness camping / hunting trips, etc. where there may not be ready access to other vehicles for jump-starting. Or - one can just simply carry a spare battery along (which many outdoors folk do just as a matter of principle.)
 
02 Northface said:
As the added AUXILIARY battery is also NOT CONNECTED to the vehicle charging system, I "condition" it once a year with my good battery charger to maintain the battery.

Why wouldn't you connect it to the vehicle charging system?  I presume the Painless setup you are using includes an isolator?
 
We do not want to connect the added "auxiliary" battery to the vehicle charging system because:

If you connect the "auxiliary" battery to the vehicle charging system, by virtue of THAT connection, you are actually then connecting the "auxiliary" battery DIRECTLY to the MAIN battery too. As the alternator is itself connected DIRECTLY to the MAIN battery, adding a connection from the alternator to the "auxiliary" battery effectively places BOTH batteries in parallel, with NO isolation between them. Having the two batteries connected together, in parallel, is NOT what is wanted here. And that actually DEFEATS the "SWITCHING" part of the Painless Performance System. Any short or load on the MAIN battery that drains it would ALSO drain the "auxiliary" battery (since they are NOW connected together in parallel.) The idea and design of the Painless Performance Battery Switch System #40102 is to keep the two batteries totally isolated from each other until the backup "auxiliary" battery needs to be switched in to start the vehicle from a LOW or DEAD MAIN battery.

As to an isolator, the "Painless Performance #40102" system does not provide that type of design. I have read that there are other systems that do, but I have not dealt with those nor have I any direct knowledge concerning their design and implementation. There are many dual battery systems on the market.

The Painless Performance Battery Switch System #40102 requires that it be installed and connected only as the manufacturer specifies, otherwise it will not function as intended, and that will lead to problematic electrical issues.

:B:
 
It all depends on what you are doing with your batteries. Be aware you must occasionally charge your battery and it is not a bad thing to run two batteries in parallel while the truck is running. It is fine if your load comes off both batteries. It will actually pull from the battery with higher voltage.

The only two issues you have with batteries being in parallel while running is that you are doubling the internal resistance which really only is an issue during starting (And potentially with audio systems but generally not an issue with most audio systems.)

And the other is if one cell goes out in one of the batteries it can have the effect of putting a load on the charging system that isn't there if the battery is disconnected.

There are intelligent charging systems available that are supposed to keep them apart and only charge them when necessary. You can also install a secondary alternator or a diode based battery isolator if you desire although diodes tend to drop your available voltage by .4-.7  depending on quality of diodes used.

In the vast majority of vehicles that are adding a secondary battery we are running the secondary battery for ignition off usage which allows us to not discharge the main battery so we can start the vehicle. That is how mine is wired so in my case I most definitely want it connected ANY time the vehicle is running. Because the internal resistance increases when they are in parallel I do NOT want the batteries in parallel when starting unless my primary battery is bad.

My setup is very similar to the one with pictures.. I even used the same components although probably rated differently. I do NOT have the plexi cover although that looks like a good idea.

Rodney
 
02 Northface said:
We do not want to connect the added "auxiliary" battery to the vehicle charging system because:

If you connect the "auxiliary" battery to the vehicle charging system, by virtue of THAT connection, you are actually then connecting the "auxiliary" battery DIRECTLY to the MAIN battery too. As the alternator is itself connected DIRECTLY to the MAIN battery, adding a connection from the alternator to the "auxiliary" battery effectively places BOTH batteries in parallel, with NO isolation between them. Having the two batteries connected together, in parallel, is NOT what is wanted here. And that actually DEFEATS the "SWITCHING" part of the Painless Performance System. Any short or load on the MAIN battery that drains it would ALSO drain the "auxiliary" battery (since they are NOW connected together in parallel.) The idea and design of the Painless Performance Battery Switch System #40102 is to keep the two batteries totally isolated from each other until the backup "auxiliary" battery needs to be switched in to start the vehicle from a LOW or DEAD MAIN battery.

As to an isolator, the "Painless Performance #40102" system does not provide that type of design. I have read that there are other systems that do, but I have not dealt with those nor have I any direct knowledge concerning their design and implementation. There are many dual battery systems on the market.

The Painless Performance Battery Switch System #40102 requires that it be installed and connected only as the manufacturer specifies, otherwise it will not function as intended, and that will lead to problematic electrical issues.

:B:

From the description I've found on that Painless kit on Jegs web site it sounds like switch position 2 does have an isolation function in that it only connects the second battery when the ignition is on.  "?Position two connects the auxiliary battery while the ignition is on. Green light."  This prevents any short or load from draining both batteries when the ignition is off.
 
Im wanting to do the same to my 08. Mind if I ask what all you used on it?


krazycarguy said:
Or you can get the digital power manager like i have. Its all automatic.
 
I got the kit painless sells. comes with everything you need except the second battery.

10370903_10154726428500652_5125284552135223333_n.jpg


Tapped into the OE battery here:

10678861_10154726428475652_7916305087834290111_n.jpg
 
It should be noted that first gen trucks have their battery in the front position. Later generation batteries have their battery in the rear position.

So depending on which year you do it is otherwise the same installation.
Mine is first gen so my second battery is in the rear position.

I personally used the PAC-200 amp Battery Isolation Solenoid. I mounted this near the battery but I could have mounted it just about anywhere. There is a hole in the battery tray as mentioned earlier. I found that my solenoid stuck above the battery tray so I drilled new holes about a half inch down and my solenoid is sitting very nicely on the side of the battery tray. I grounded the switching connection closest to the battery. The powered portion is the one away from the battery. I ran the powered portion to the under hood fuse panel and used an "add a circuit" to use the SEO fuse. This is an ignition lead used to normally run add on overhead lights which my truck does not have.

I used a stinger 200 amp Breaker similar to the one in the picture. I liked this style because the mounting holes are both on the top with the wire access on the bottom. I bolted this to the top of the firewall in same place earlier poster bolted his. It really is the only good place to put it.

You want to make sure you fuse all POS battery connections as close to the battery as possible to prevent vehicle fires. I have an inline 200 amp circuit breaker on the wire feeding my secondary battery within like 4 inches of where I have it connected. I used an aftermarket "unbranded" circuit breaker. This is wire tied to the wireloom near by. 

I realized in my setup I need a different connector to run to my computer so I will be running another inline circuit breaker on the line to my main auxilary feed. I was going to feed this from the aux battery post on the solenoid but I later realized If I trip the breaker on the aux battery I won't know it until my computer won't boot up. So I will be running it directly to the battery. This will allow me to check the voltage on the battery and if it is 14+ volts during vehicle run time I know all of the breakers are connected.

I ran my pos wire from the solenoid up along the top of the fire wall wire tied to a wire already running there. That wire goes over the top of the engine under the engine cover and combines with a major harness that goes to the underhood fuse box and runs near the red plastic protector that houses the alternator connection to the starter power wire. I ran my supply wire the whole length of that major harness to the red protector. I enlarged the holes on the plastic piece to accept my wire and attached it directly to the lug the alternator wire is hooked to.

I used 4 gauge wire which appears to be what is also used by the factory.

In my truck I used a pass through stud so I can tap off the connection on the interior of my truck. I currently feed this with a 4 gauge wire and on the inside I have an 8 gauge wire running from this stud running to my computer power distribution block. I may eventually upgrade the wire from the battery to a 0 gauge wire to the engine side of the stud to power my audio system. I would then run a 0 gauge wire to the amplifier deck in the rear. But since I am using this stud I can still use the 8 gauge wire to power the computer accessories without issue.

When in doubt use a bigger wire size. Never can have too big a wire.

My ground I ran a 4ga wire to the bracket mount bolts on the fire wall for the battery tray. I then ran a wire from there to the bolt on the dip stick tube. This grounds me to the body with this battery so I don't have any issues and the one from the body to the engine block grounds it for charging purposes.

I will be increasing the size of the wire from the alternator to probably an 8 gauge wire. Looks like a 10 gauge wire from factory.
 
Assuming your primary battery, or auxiliary battery, is big enough, can this set up be used to power a winch when necessary?  My thought is using the auxiliary battery as the winch power battery and using it when one needs to use the winch (emergency).  Or is that a bad idea and should I plan on just using a big (amp wise) battery for my primary and run the winch off it?

Seems the auxiliary battery running the winch would be a better idea to me as the whole idea of the auxiliary, in this set up, is for emergencies.  The rest of the truck can run off the primary. 

Thoughts?
 
The Painless aux battery kit and the Wrangler kit both tie the batteries together after the engine is running to charge the aux and isolates them when the ignition is off. You can override and tie them together for jump starting yourself or large load like winching or stereo or the off postion to totally isolate both batteries from each other.


The ground from the aux battery should go to the engine block and also one to the frame if you want the best current flow to the starter and any add on equipment, i.e. stereo, amps, winch or lights.



The only problem with Painless's Digital Power Management is that you can not attach any load to the aux battery or you fry the digital controller.
 
That's my issue with the Digital unit also. They come with 4 gauge wire a bit too small for me.
I have 0 gauge wire through out the system, I still do not understand the idea of a battery you can't recharge from the alternator
 
MS03 2500 said:
That's my issue with the Digital unit also. They come with 4 gauge wire a bit too small for me.
I have 0 gauge wire through out the system, I still do not understand the idea of a battery you can't recharge from the alternator


It's only meant to prevent the main battery from draining, all loads connect to the main battery. They do have a digital power manager that has a solenoid relay that allows you to jump start yourself, but for me I like to have my loads connected to the aux battery. It's still a great product just has it's pros and cons like everything.
 
I hear ya, but I use the second battery to run the mods. The engine fans are 50 watts each which I run off the second battery.
 
Back
Top