Dual battery setup

[Miami Son]

I want to add a second battery to my 2017 Suburban. There is already a place for one under the hood. Anybody done this? Any links to equipment needed and how to hook up? What size/rating isolator do I need? Thanks.

[Jim Fleck]

I'm in the same boat. 2018 sierra SLE.

I have aftermarket strobes, that could be wired to a second battery. I would be able to run them for many hours without running the motor and also without fear of running down the primary battery. My truck has a 110 volt outlet that is only live when running the motor. Wondering how long it could run on a second battery if I could relocate that power lead.

Any help would be great!

[ripinlip]

Exact same situation here - really could use a sep by step. I’m running a 1/0 gauge to the back for some amps and I want to power those totally from the 2nd battery (but I want that 2nd battery to charge from the alternator )


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[Jim Fleck]

I am glad I am not alone!

We may end up leading the way. I will list a few more thoughts I have been thinking about.

1. I plan on using a DEEP CYCLE battery to achieve a long run time without running the motor.

2. I plan on having two nice white LED flood lights (adjustable angels) to illuminate a large work area.

 A. These lights should be mounted as high as possible to prevent blinding self going back to the tailgate ( my portable work bench).

 B. I was considering using the trailer hot lead for the power source as it is factory and should be a 10 or 12 gage wire.

 C. I would have to verify it comes from the B+ (always hot). Then re-locate that lead to my future second battery.

     I seldom tow a trailer that would benefit from the intended use (recharging the trailers battery used for powering the electric brakes      in the event of break away). Or just run my own lead to the back myself.

D. I have may want to have this switch mounted in the cab next to the after market strobe switches installed before I got the truck             from my employer. I get to take this work truck home each day!

 

I want to keep all this practical as to be able to get it done. Have it be well thought through. And beneficial fore regular use.

 

JIm 

 

[Jim Fleck]

I forgot to ask what you would like to power at the back of your truck?

I also plan on using a good quality battery isolator. If cost does not go to high displaying voltage and amps in the cab of the second battery would be great!

[Gmman]

I added the second battery to my 2017. Piece of cake. All factory stuff.

[Jim Fleck]

Hi Dale, 

Did you use a deep cycle battery?

I would like to use the standard tapered block to hold down the second battery rather than a bungee cord.

deep cycle batteries don't have the indent do they?

Did you use a battery isolator? 

What are you powering?

[AzCoronaDog]

I put dual batteries in my 1990 Suburban, and I am working on upgrading to a 2016+ Yukon XL and already noticed the 2nd batter tray is already there.

 

For the 1990, I had to buy the 2nd tray that the diesel versions used.  I discovered that the 1990 wiring was essentially split into two circuits at the fuse block, with the engine stuff on one and all the accessory items, headlights, interior lights, radio, etc. on the other.  The two main feeds were joined at the alternator so it was easy to separate.  I believe this was due to using the same basic wiring as the trucks of that year, some of which offered a camper wiring option. I am really hoping there may be a similar split for the newer models.

 

At first I used a battery isolator for charging, but switched to a constant duty rated solenoid, as it was more reliable, much higher amperage ability and 0 voltage drop.   It was wired to the fuse box at a point that was hot only in run, not accessory or start.  I put a momentary switch in the dash that would engage the solenoid from the 2nd battery, so if for some reason the primary battery was weak, I could jump start myself without using cables. 

I also mounted 2 battery tenders under the hood and put a marine grade 110v covered connector in the fender so I can plug it in and keep everything charged when I don't use the truck for long periods.

 

I use an AGM primary battery and a lead acid deep cycle secondary.  I tried an AGM deep cycle, but it had a lot lower capacity and did not last anywhere close to the lead acid ones.  I do have to check the water level fairly often in the summers here, but the trade off was worth it to me.

 

[davester]

110V AC uses a lot of amps from a 12V DC source.  Roughly, that battery will need to provide roughly 10X the current that whatever device you have plugged in uses (or more if the converter is cheap).  So, something like a hair dryer on high takes about 15A, the battery has to provide about 150A.

 

You want to at least have a setup so the 110V socket only goes live when something is plugged in, and you remember to always unplug it when you are not using it.  Or a manual switch, but you have to remember to always switch it off.  Converters will drain the battery just leaving them on, as it takes some power just to have 110V available at the socket, even if there is no current draw.