Disco 1 Dual Battery Setup Advice

peytondisco98

Active member
Nov 25, 2020
40
5
NYC
Hi guys, I'd like to add another battery to the rig. Curious what some of you have done. I always worry when I'm out in the woods or mountains and turn off the truck that something will drain the battery, and then I can't start it up back up. Takes away from some of the enjoyment.

I've also noticed that it pulls a lot of power when I run 4 or 6 Hellas on a night.


Thanks!
 

dos531

Active member
Feb 1, 2016
27
7
Rowland Heights, CA
If you're just worried about not being able to start it, pick up at $50 jump pack from amazon and youll always be able to start it. I only have 1 agm battery and I run a fridge and compressor, lights, winch etc. Its never been an issue, but I keep a jump pack in the glove compartment just in case.

As for the lights if you're pulling too many amps then an extra battery wont help. What you need is a high amp alternator. That said, I doubt a few lights are a problem for the factory charging system.
 
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Knightspirit

Well-known member
Sep 22, 2019
251
84
Mount Shasta, CA
I have a dual battery set up. My second battery is a deep cycle Optima (Yellow top) which I have connected to a charging station in the back. You'll need the battery:


Battery isolator:


Fuse:


Here's what my charging panel looks like:

IMG_5329.JPG
 

Tugela

Well-known member
May 21, 2007
4,754
562
Seattle
Not sure what your current alternator setup is, but if you want a bit more juice, Will Tillery is running a special on uprated models in the parts for sale section. It's a good deal, regardless.
 

jymmiejamz

Well-known member
Dec 5, 2004
6,008
361
35
Los Angeles, Ca
If you're just worried about not being able to start it, pick up at $50 jump pack from amazon and youll always be able to start it. I only have 1 agm battery and I run a fridge and compressor, lights, winch etc. Its never been an issue, but I keep a jump pack in the glove compartment just in case.

Agreed 100% on having just one battery. I would make battery maintenance a priority though.

As for those jump packs, they work great until the don't and usually fail suddenly. I've seen several of them (lots of different brands) fail over the years, including my own Snap On unit last week. Every time they fail the same way, which is without warning. Great to have, but wouldn't plan on relying on one.
 

robertf

Well-known member
Jan 22, 2006
4,781
358
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That 140 amp rated isolator is not enough. Starter pulls more than that, and a winch can pull around 400
 

peytondisco98

Active member
Nov 25, 2020
40
5
NYC
Decided to pull out the bottle jack, make a bracket, and put the second battery there. Need to find a good isolator and then wire it to a non-used switch on the dash. Maybe fog lights. Does anyone know anyone who's used this area for a second battery?
 

Knightspirit

Well-known member
Sep 22, 2019
251
84
Mount Shasta, CA
That 140 amp rated isolator is not enough. Starter pulls more than that, and a winch can pull around 400
Interesting - so what happens if the amps go above the rated limit? Does it just pull from the other battery as well? Since I am not using that much for anything in the back (just a fridge at the moment) I assume it would just drain the one battery and not affect the other.

Meanwhile - peytondisco98 - please list your final set up for us. Maybe I'll swap out my isolator. My battery is in that slot - it fits, but you might need to move your steering fluid reservoir.
 

robertf

Well-known member
Jan 22, 2006
4,781
358
-
Thats not at all how electricity works.

if you draw more power than the rating the results can range from nothing to a burning vehicle. Youd have to ask the manufacturer and they’re unlikely to tell you what the weak point is.
 

Swedjen2

Well-known member
Sep 12, 2018
594
127
California
Hi guys, I'd like to add another battery to the rig. Curious what some of you have done. I always worry when I'm out in the woods or mountains and turn off the truck that something will drain the battery, and then I can't start it up back up. Takes away from some of the enjoyment.

I've also noticed that it pulls a lot of power when I run 4 or 6 Hellas on a night.


Thanks!
Jymmejamz has once again been subsumed by his alter ego - DebbieDowner. What he says may be true of several chargers over the years, but it's still great insurance. Get your NOCO Boost at Amazon1608138937303.png
 

ERover82

Well-known member
Nov 26, 2011
3,899
450
Darien Gap
Interesting - so what happens if the amps go above the rated limit? Does it just pull from the other battery as well? Since I am not using that much for anything in the back (just a fridge at the moment) I assume it would just drain the one battery and not affect the other.

Assuming equal charge level, each battery would supply half of drawn current. A 250 amp starter would draw 125amps from each battery and through the isolator. A winch drawing 400 amps would pull 200 amps through the isolator and over a longer period. It does appear that a 140 amp rated isolator could be insufficient in some scenarios.
 

ERover82

Well-known member
Nov 26, 2011
3,899
450
Darien Gap
Agreed 100% on having just one battery. I would make battery maintenance a priority though.

As for those jump packs, they work great until the don't and usually fail suddenly. I've seen several of them (lots of different brands) fail over the years, including my own Snap On unit last week. Every time they fail the same way, which is without warning. Great to have, but wouldn't plan on relying on one.

What does Mr. Jamz rely on? Redundant Strap On jump packs, solar, mobile hamster wheel generator?
 

Knightspirit

Well-known member
Sep 22, 2019
251
84
Mount Shasta, CA
I don't see much on the market above 200 amps as far as an isolator - at least not for vehicles. This one looks promising though - at 300 amps.


The 400+ amp version requires 300+ amps charging source, so that's probably not practical....

Then I was looking on Ebay and found this - seems too easy and too cheap!

 
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hysteria411

Member
Oct 15, 2019
6
3
Indiana
I use a m-acr to charge & isolate my second battery, but also have a high amperage starter relay wired parallel to the m-acr that I can close with the flip of a switch. That allows manual combining of the batteries and a more robust path for high current draw activities such as winching or starting.
 

Icannap1

Well-known member
Mar 3, 2015
123
21
OC, CA
I am using the PAC-500 battery isolator and for the controller i am using Westin 47-3800 dual battery system. It has been installed for 3 years with no issues and a Renogy 100 watt solar panel mounted under the roof rack. Rover could be parked for 2-3 months at a time and it always has power. You will need to build it for your needs buy upgrading the cabling.
 

logan_gibson

Well-known member
Dec 20, 2016
258
47
Alabama
Decided to pull out the bottle jack, make a bracket, and put the second battery there. Need to find a good isolator and then wire it to a non-used switch on the dash. Maybe fog lights. Does anyone know anyone who's used this area for a second battery?
I've used it as a 2nd battery location.
Before I moved mine to the rear.

I did have to extend the power steering res. bracket out a bit further.

I just grabbed a generic battery hold down kit from the store and used that.

I've got the TMAX dual battery kit installed, its nice because I can quickly link the two, and the rest of the time it just does an auto link.
You can put the same kit together cheaper if you want to, this is more of a quick toss-in kit.

All of my wiring ran along the firewall to each battery. The battery isolator is over on the firewall by the washer bottle.

I've linked it together before to jump the truck, worked fine.
 

peytondisco98

Active member
Nov 25, 2020
40
5
NYC
Update:

Positives: The battery fits perfectly where the bottle jack used to live! Ne needs to make a bracket.

Negative: Need to modify the air intake housing, and move the power steering reservoir. the lines are hard on the power steering, so had to order new ones F###. Re air intake housing. I'm considering grinding the hole from the top to open it up. So it can pull more air from higher on the housing. Anyone had any luck (besides going the snorkel route) modifying the air intake?
 

robertf

Well-known member
Jan 22, 2006
4,781
358
-
I think the older air cleaner that pre 94 stuff got clears a second battery. Youd need to add a temp sensor bung for a 4.0 truck.
 

nfbeckman

Well-known member
Dec 10, 2013
110
14
Memphis,TN
Couldn’t you just run a second battery that is identical to the starting battery and avoid needing a fancy isolation switch? If the batteries are the same then they won’t compete. You could run heavy gauge leads connecting them and a manual cutoff switch to avoid drawing down the starting battery at camp.
 

robertf

Well-known member
Jan 22, 2006
4,781
358
-
Thats how special vehicles did it
 

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