How to make a cheap isolated dual-battery setup for $50

[gershee]

Wow you guys are SUPER helpful.
I should've posted a long time ago.

So I'm gonna go ahead and order that Stinger Isolator (since none of you told me otherwise).
The cables I will get larger and higher quality (thanks for guidance guys, I won't cut corners here).

What you said about having too large an inverter.. Got me thinking.. I would rather have too larger than too small. I defo want to be able to have alot of random (smaller) things pulling juice at the same time without worry. Eventually I will try a blender or juicer as well (which I know need a lot more juice). Am I still overboard with 1100watt inverter?
And one last thing, I still don't know why I would want 2 6volt deep cycle batteries wired in series as opposed to 1 12volt deep cycle. The lifecycle is longer? They maintain charge better? Will this really affect me in my minimal setting? Like I said, eventually I would like solar for those times I'm in one place for days or weeks(burning man).. A few people mentioned to get the 6volt batteries instead, just never really understood why.


Thanks again. You guys were more than helpful.

 

[PIC4GOD]

6 volt deep cycle batteries are used because they are inexpensive but at the cost of weight. The best way to go is a 12 volt AGM battery for capacity, starting power, and weight savings. Keep in mind that your batteries should also be matched for effective charging.

 

[patoz]

And one last thing, I still don't know why I would want 2 6volt deep cycle batteries wired in series as opposed to 1 12volt deep cycle. The lifecycle is longer? They maintain charge better? Will this really affect me in my minimal setting? Like I said, eventually I would like solar for those times I'm in one place for days or weeks(burning man).. A few people mentioned to get the 6volt batteries instead, just never really understood why.

Thanks again. You guys were more than helpful.

As they say, 'Ya gotta do the math'! I am currently using 2 Trojan T-105 6VDC deep cycle golf cart batteries wired in series as the house bank for my camper trailer, and here's why...

6V golf cart batteries are somewhat taller and much heavier than standard light duty truck batteries. They have much larger and thicker lead plates in them, which is why they are so much heavier, and why they last longer. A properly charged and for deep cycle battery can last up to 6 - 8 years, whereas an ordinary automobile or marine hybrid start/deep cycle battery may only last 3 - 4 years, if that long.

When you figure up the Rated AH Capacity for each system, the two 6VDC Trojan T-105s are rated at 225 AH and in series still have 225 AH total, and the 12VDC Lifeline Group 31T is only rated at 105 AH. So, putting two of these in parallel still only gives you 210 AH total. Now the kicker is: Trojan T-105 @ $150.00 x 2 = $300.00 and Lifeline Group 31T @ $325.00 x 2 = $650.00.

So, I saved $325.00 and gained 15 AH by going with the 6VDC Trojans.

When I purchased my Inverter/Charger/Converter, I upgraded to a Magnum Energy 2000W Inverter with 100A Charger, so I will be adding two more Trojan T-105s in series and then parallel with the original two, to create a single 12VDC 450 AH four battery bank. I'm also planning on adding 500 Watts of Solar on the roof to charge them when off the grid or in a disaster situation.

 

[loonwheeler]

When you figure up the Rated AH Capacity for each system, the two 6VDC Trojan T-105s are rated at 225 AH and in series still have 225 AH total, and the 12VDC Lifeline Group 31T is only rated at 105 AH. So, putting two of these in parallel still only gives you 210 AH total. Now the kicker is: Trojan T-105 @ $150.00 x 2 = $300.00 and Lifeline Group 31T @ $325.00 x 2 = $650.00.

So, I saved $325.00 and gained 15 AH by going with the 6VDC Trojans.

Not only that - but doing the math you saved a lot more when considering ($$)(Ah)/Yr. Weight, space, and location considerations aside (I know, a BIG assumption), this one of the main calculations to consider when choosing a battery system.

 

[inv3ctiv3]

Sorry guys I suck at all things electrical - if I wanted to wire in a fuse block like this (https://www.amazon.com/Blue-Systems..._UL480_SR312,480_&refRID=K2009H0XMWQMZ99RS8HP) where would I do so in this dual battery set up? I'd want the fuse block to be used on the aux battery.
Thanks!

 

[dlichterman]

Sorry guys I suck at all things electrical - if I wanted to wire in a fuse block like this (https://www.amazon.com/Blue-Systems..._UL480_SR312,480_&refRID=K2009H0XMWQMZ99RS8HP) where would I do so in this dual battery set up? I'd want the fuse block to be used on the aux battery.
Thanks!

I am using this one here because it has positive and negative all together. You would attach directly to the aux battery.

 

[gershee]

in regard to "batteries should be matching"..
so i just want to make sure..
i have a duralast 36R-DL as my starter battery..
for my house battery i found a good one at sam's club for $80.. duracell 24dcc
can someone tell me if it will be fine for my second battery?
they are both 12v.. what else do i need to check for compatibility?

 

[dwh]

in regard to "batteries should be matching"..
so i just want to make sure..
i have a duralast 36R-DL as my starter battery..
for my house battery i found a good one at sam's club for $80.. duracell 24dcc
can someone tell me if it will be fine for my second battery?
they are both 12v.. what else do i need to check for compatibility?View attachment 350812

The "batteries must be identical" rule only applies when the batteries are permanently connected together to form a battery bank.

If they are only connected together when charging (like the relay setup in this thread), then it doesn't matter as long as they are both the same "nominal voltage" - in other words, both "12v" batteries.

That applies to lead-acid. Don't mix lead-acid with lithium, and it's not a good idea to mix gel type lead-acid with flooded or agm, but you can mix flooded and agm with no worries.

 

[patoz]

Dwh, don't forget the age thing for battery banks also...

I sure wish the price of lithium batteries would come down...maybe one day!

 

[DiploStrat]

One more time with feeling:

-- Batteries in the same bank: You want them to be same make/model; sequential serial numbers if you can do it.

-- Batteries connected only when under charge: Need to have similar charge profiles. For example, I run Lead Calcium AGM batteries as starter batteries (GM OEM) and deep cycle AGM as camper batteries. After two years, my camper batteries show no signs of age.

 

[evldave]

Hi folks-

I quick update on this setup. I wrote this post about 4-1/2 years ago using my setup at the time (and a LOT of beer ). Since then, I had to replace one of my DieHard batteries under warranty, but other than that I have had ZERO issues. I have made no changes to the setup, no upgrade of the cables/solenoid/etc.

In the 4+ years of this setup, I have made many longer trips, driven many thousands of miles offroad, run down the batteries and charged them up via alternator, solar, trickle chargers and battery starters. I have self-jumped more times than I can count. I rarely drive this truck anymore, so it now sits for long periods of time. Every few months I forget to start it and have to jump off the 'house' battery and it starts every time.

Basically, for anyone who might have concerns about the quality of this setup, used in real-life off-road situations (and now just sitting and collecting dust for months at a time), I can vouch for how well it has performed. I'm looking for a full-size SUV (Suburban/Excursion/etc) and will pretty much exactly replicate this setup in my new rig.

Cheers

Dave

 

[Bear in NM]

Thanks for the update, and especially THANK YOU for starting this thread. It was sort of my jumping off point, and now I am in the deep end. Having the second battery installed is going to be such a relief off of my mind, as in the past when going to the ranch alone, I would drag either a second loose battery, or my generator and charger, or all three. Now with the second battery and solar, I wont have so many panic attacks about doors being closed, dome lights on, etc.

Craig

 

[bigoldford]

I'm sorry if this was covered in the miles of thread we have here.

I drive an 88 diesel ford. From the factory I already have dual batteries in parallel.

I want to be able to run small lights, a fridge and whatnot for multiple days while out on trips.

Should I add a third "house battery" (and how would I wire that with the current system.)

Should I run a solar panel to charge my current dual battery setup.

Or should I do a combo of the both where I charge the third "house" battery with a solar panel?

All of this talk of cheap solar makes me want to set one up.

 

[dlichterman]

I'm sorry if this was covered in the miles of thread we have here.

I drive an 88 diesel ford. From the factory I already have dual batteries in parallel.

I want to be able to run small lights, a fridge and whatnot for multiple days while out on trips.

Should I add a third "house battery" (and how would I wire that with the current system.)

Should I run a solar panel to charge my current dual battery setup.

Or should I do a combo of the both where I charge the third "house" battery with a solar panel?

All of this talk of cheap solar makes me want to set one up.

Is the reasoning for the dual batteries from the factory that you need the power to crank the engine? I'd probably want to not mess around with what the factory did and add a 3rd isolated battery just to make sure I can always start the truck when I want.

 

[bigoldford]

Is the reasoning for the dual batteries from the factory that you need the power to crank the engine? I'd probably want to not mess around with what the factory did and add a 3rd isolated battery just to make sure I can always start the truck when I want.

Yes, they are for cranking power. So how would one wire in a third battery to charge off of the stock alternator, yet be isolated? I should probably run a larger alternator. Also should I run a solar panel in conjunction with all of this? Or would that be overkill?