Dual Battery Setup Questions

[TJim]

Hello!

I would like to run a dual battery setup in my TJ.

The reasons are mainly for camping (fridge, charging devices, lights), but also to run my winch and air compressor without draining down my MAIN battery.

I have the following questions:

A) Can I have the following choices by using a switch? (1. running normally only the main battery, 2. running only the 2nd battery, 3. charging the MAIN and the 2ND battery)

B) Do I have to connect my devices on the second battery or is there a way to run them with either battery? (The main idea is to run i.e. the fridge with the first battery when moving, but with the second battery when camping.

C) Will I be able to jump start my car if the MAIN battery is drained, by only using the switch, and not using additional cable?

 

[Vinman]

Using a switch like this will do everything you need.

https://www.amazon.ca/dp/B000MMFJH0/?tag=tjforum-20

 

[BugoutJeep]

I've messed with batteries for close to a decade for fun and messing with solar and off-grid projects. There's also some issues you need to consider.

First off, your winch is a high draw item and most AUX batteries are deep cycle, which don't like large draws, rather being taken down slowly and further than a battery designed for short duration high draw. Therefore, I suggest you will probably want to keep your winch run straight to your main battery.

I like AGMs for off-road vehicles and I prefer a starting battery for the high draw stuff like winch and starting battery. The caveat to this is that if I'm running dual batteries for starting, I prefer dual purpose batteries if I'm WAY above the recommended CCA. For example, Cummins recommends 900 CCA, I currently have a starting battery rated for this amount. When I go to dual starting/winching batteries my combined CCA with be like 1,200 CCA or more, so dual purpose makes sense for this application. If I run a battery isolator between those batteries, I get an even greater chance that I will always have a way to start my vehicle through battery powered means, since I'll have 3 batteries.

I would use something like

https://www.amazon.com/gp/product/B077JR6NH5/?tag=wranglerorg-20

to control the charging of your AUX battery from your main battery. I have a unit like this and it's great, when it works. Mine worked great for 1 month, but I just keep working on other stuff and not getting this thing returned. But in general, I'd look at some of the various solar charge controllers as a cheaper solution. I have this charge controller and have seen it work, but haven't personally done it.

https://www.amazon.com/gp/product/B000FIWKQE/?tag=wranglerorg-20

As a suggestion, I'd run anything that's not absolutely critical on the AUX battery. The low draw of those items will be handled just fine when the vehicle is on and the AUX battery is being charged by the alternator. Also if you're out for long periods of time without starting your engine then look into adding in some solar, especially if the engine will only be ran for short durations, since your batteries will not have as much time to fully charge and at this point consider a high output alternator.

As far as jumping your vehicle, I prefer simple and just using jumper cables for this, because it's so rare. If it's not rare then get bigger batteries.

That's just a general idea I have on batteries, if you have any questions or specifics, like AH recommendations, just let me know and I'll be glad to help since I like this subject.

 

[BugoutJeep]

Something else to consider are the units like YETI and Jackery, etc. For a quick weekend where you'll be back and able to charge for a long period of time these units are handy.

I don't recommend these units in general though, because I like that I can recharge a regular battery, depending on size at 20amps or more vs like 2 amps. Most of those units take more than a day's worth of sunlight to recharge, which sucks if you don't want to be forced to find an outlet and in those instances you would probably have to buy multiple small units so you can charge them somewhere in that 2amp range at 12 V and with the average light in most places being 5 hrs/day then your energy to perpetually keep your systems running are very low.

 

[TJim]

Something else to consider are the units like YETI and Jackery, etc. For a quick weekend where you'll be back and able to charge for a long period of time these units are handy.

I don't recommend these units in general though, because I like that I can recharge a regular battery, depending on size at 20amps or more vs like 2 amps. Most of those units take more than a day's worth of sunlight to recharge, which sucks if you don't want to be forced to find an outlet and in those instances you would probably have to buy multiple small units so you can charge them somewhere in that 2amp range at 12 V and with the average light in most places being 5 hrs/day then your energy to perpetually keep your systems running are very low.

Hey ! Thanks for the answers.

I just wanted to ask about some things:

1) I understand that I will have to use my winch with my main battery (since many CCA are required). What about the air compressor?
Is it okay to run my air compressor, fridge, camping lights, power sockets for charging from a deep cycle battery (aux)?

2) what about my switch? I want to have an in dash switch, as well as an in dash monitor (to monitor the voltage of both batteries)
the options of my switch will be the following?
1. running normally only the main battery, 2. running only the 2nd battery, 3. charging the MAIN and the 2ND battery

 

[Wildman]

This is what I have on my TJ.

https://www.dirtyparts.com/store/detail.cfm/BATTERY-MANAGER-CONTROL-KIT/pid-80492
In the normal position it charges both batteries and only uses the main. In emergency mode it connects them both together for more cranking power or for when winching. And then in off mode it just charges the main battery.
They also have a dual battery tray that they offer.

https://www.dirtyparts.com/store/detail.cfm/AUX-BATTERY-TRAY-JEEP-TJ-W-AC/pid-123742
Painless Wiring also makes a switch kit.

https://www.painlessperformance.com/wc/40103

 

[TJim]

This is what I have on my TJ.

https://www.dirtyparts.com/store/detail.cfm/BATTERY-MANAGER-CONTROL-KIT/pid-80492
In the normal position it charges both batteries and only uses the main. In emergency mode it connects them both together for more cranking power or for when winching. And then in off mode it just charges the main battery.
They also have a dual battery tray that they offer.

https://www.dirtyparts.com/store/detail.cfm/AUX-BATTERY-TRAY-JEEP-TJ-W-AC/pid-123742
Painless Wiring also makes a switch kit.

https://www.painlessperformance.com/wc/40103

Thats cool, but I would need something for camping purposes more.

For example, I would like a choice on my switch that I would only use the 2nd (aux) battery (isolate it from the main battery) without the key on, so I could my power my fridge, and other lights/accessories when camping.

 

[BuildBreakRepeat]

Thats cool, but I would need something for camping purposes more.

For example, I would like a choice on my switch that I would only use the 2nd (aux) battery (isolate it from the main battery) without the key on, so I could my power my fridge, and other lights/accessories when camping.

Look into the CTEK D250SA - Its what I’m getting for my Jeep. Maintains the “house” battery with either alternator or solar power, and uses it to boost a dead battery or run any accessories while automatically optimizing the flow/charge.

https://www.ctek.com/products/vehicle/20a-off-grid

 

[astjp2]

I see a motorhome in your future...

 

[pagrey]

Plenty of good information on Expedition Portal and down under Ronny Dahl has a few good videos on the subject.
BEST 12 volt 4 Wheeling setup yet, plus advice & reviews
His videos are great with detailed descriptions that link to the section you are interested in. This is a great site for Jeeps but most dual battery setups I've read about on just about all the Jeep forums are really winch oriented and not what you're going for.

 

[BugoutJeep]

Thats cool, but I would need something for camping purposes more.

For example, I would like a choice on my switch that I would only use the 2nd (aux) battery (isolate it from the main battery) without the key on, so I could my power my fridge, and other lights/accessories when camping.

Most charge controllers will stop charging the aux battery once they hit a voltage that will be completely safe on your main battery.

Everything you described, sounds like they would be fine on most Aux batteries. Don't forget that a lot of cheap solar charge controllers will work fine for charging the aux battery from the main battery, but shut off without destroying the main battery. Personally I use solar charge controller as my spare now that I realized my RedArc isn't working.

But just look for a quality charge controller and as a bonus I'd look for one with easy additional inputs. Maybe check to make sure that when you're near 120v that you can top off just in case too.

 

[BugoutJeep]

Another note. For a Jeep I like MC4 connectors. Anderson powerpoles are nice too, but I don't think they are as good if exposed to weather, but maybe I'm wrong. I run all my solar with MC4 connectors and really like them.

For inline fuses I like:
https://www.amazon.com/dp/B00HKI93NA/?tag=wranglerorg-20

However if you have a bunch of other fuses, then no big deal, but I happen to already be running those style heatshrinked so it's kinda low profile.

I like marine wire as well. I'm sure I'm forgetting some other stuff that's handy, but definitely get small voltage read-outs as that's very useful and I like inline MC4 type connector multi meter.

https://www.amazon.com/gp/product/B07GH4QS1Z/?tag=wranglerorg-20

 

[TurboTJ]

I considered installing dual batteries until I determined that a single large battery would have more capacity than two of the smaller batteries I would have to use in a dual installation.

 

[BugoutJeep]

Which battery did you go with?

I still prefer dual batteries. I like separating the different systems. Also I haven't been using AH as a judge for my starting battery, but my starting system isn't OEM and CCA and running a winch occasionally are my issues for that battery/batteries.

 

[BuildBreakRepeat]

Which battery did you go with?

I still prefer dual batteries. I like separating the different systems. Also I haven't been using AH as a judge for my starting battery, but my starting system isn't OEM and CCA and running a winch occasionally are my issues for that battery/batteries.

Being a diesel supports running two, it’s the smarter choice. I like the idea of always being able to jump myself in emergencies

 

[BugoutJeep]

Well if the batteries are isolated that works. In my 3/4 truck I don't have them isolated and if one fails it'll kill the second battery. Eventually that one is gonna get a L16 battery (those could be 6V so I'd want to go with 2) or 2 gc2s for an auxiliary system.

 

[BuildBreakRepeat]

Well if the batteries are isolated that works. In my 3/4 truck I don't have them isolated and if one fails it'll kill the second battery. Eventually that one is gonna get a L16 battery (those could be 6V so I'd want to go with 2) or 2 gc2s for an auxiliary system.

I can’t remember where I saw it, but there was an isolater that only connected them with a trigger wire, so that when you turned the key the engine had dual battery power but they were separated during normal use so one wouldn’t drain.

 

[ac_]

I am running dual Yellow tops with the painless switch mentioned earlier.

How it works is the switch all of the way up (green Light) it is using/charging both batteries. Switch in the middle only drive battery. the lower level (red light) Jumps your drive battery off of your aux. When your care is off whatever is connected to your aux battery won't affect your drive battery. Unless you put it in the red mode then both batteries are hot.

That is how the switch works.

I have a write up on this forum.
https://wranglertjforum.com/threads...es-in-your-jeep-wrangler-tj.7166/#post-288036
Check it out, and let me know if you have any questions

 

[Ledfoot Lou]

You should look into the blue sea automatic charging relay like the 7622. It's what i run on my GMC truck i use for camping. When the alternator is charging it automatically connects the 2 batteries together so they both charge. Then when you turn the vehicle off it automatically disconnects the two. You just wire up your fridge and winch to the 2nd battery and you'll never have to worry about killing the main battery. You also won't touch the factory wiring. The yellow switch on top allows you to permantenly lock the two together if you want extra juice winching, or permanently disconnect them so the 2nd battery wont charge. The 7622 also comes with a switch you can remotely mount to control the same functions that the manual override yellow switch does. This set up is nice because you don't have to remember to do anything switching, it always works as you'll want 99% of the time. Blue sea is made for house boats and yachts where power failures are serious on open water so they're real high quality.

 

[TJim]

I am running dual Yellow tops with the painless switch mentioned earlier.

How it works is the switch all of the way up (green Light) it is using/charging both batteries. Switch in the middle only drive battery. the lower level (red light) Jumps your drive battery off of your aux. When your care is off whatever is connected to your aux battery won't affect your drive battery. Unless you put it in the red mode then both batteries are hot.

That is how the switch works.

I have a write up on this forum.
https://wranglertjforum.com/threads...es-in-your-jeep-wrangler-tj.7166/#post-288036
Check it out, and let me know if you have any questions

so about the switch:

No.1 position: normal - only main battery
No. 2 position: using Main & Aux - Charging Main & Aux
No. 3 position: connects Aux to Main to jump start.

Can I use only the second? for example when engine is off. to run accessories for camping.
But to isolate the second, so I can run everything without worry to drain the main.