Simple $75 Dual Battery Setup

You don't have to spend hundreds or thousands of dollars on a dual battery system. If your requirements are straightforward, you can set up a simple system for about $75

Have a Refrigerator? Lights? Lots of accessories? The last thing you want is to kill your cars starting battery. A dual battery setup will run your accessories off a second battery so your car will always start! In this video we install and test a very simple dual battery setup.

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[davidetzel]

I have all but put a duel battery set up out of my mind due to the cost but with this set up and the ability to add and subtract components it’s now number 2 or 3 on the list. It’s great to see both ends of the spectrum on projects for those of us that can only afford so much at one time. Thanks.

[GorsuchCody]

I love channels that share affordable not “cheap” options for us average folks out there. Thanks for all you guys do!

[themastercarpenter]

very well done video, mic'd up so we can hear you, no annoying music, and straight to the point ! Thanks for the great info! Gonna work on mine soon, since it only takes me 10 minutes as well:)

[wanderingtrd]

This is awesome! In a time with companies inflating prices for everyone wanting to just get safely outdoors and back these videos are essential! Thanks Michael and Corrie!

[JeffPalmer]

Nice video. a couple things worth mentioning: @9:20 with the relay wired to the ignition, it should be pointed out that if the aux battery is severly discharged (after several days of overlanding for example) then your starting battery is trying to start your vehicle AND balance the charge between the two batteries at once. luckily, with the way you've wired it to the power antenna wire, you can just turn off the stereo, to force the 2 batteries to isolate again. Very clever, even if it wasn't called out in the video.

[Alan-mwbs]

Elegant, simple system. You really don't need any more. I've had a similar system in my 11 year old Troopy (VDJ78R) since new with a voltage sensitive relay (VSR) instead of an ignition switch activated one. The VSR has the small advantage of always ensuring that the cranking battery is fully charged before charging the house battery. I have an 80lt fridge, a handful of LED lights and the occasional USB powered device drawing from the house battery which is also augmented by a 200w solar panel. For all practical purposes there seems no need for a state of the art (expensive) battery management system that I can see. I love your videos.

[ItsMeGiga]

Edit: all these points are addressed in an earlier post!

Excellent build! The only thing I'd like to point out is that when charging directly from the alternator like this both batteries should be the same in capacity and composition (ie lead acid). If you want to use a larger or different composition like I did (agm solar 100ah battery or the newer lifepo4 batteries) you absolutely need a dc to dc charge controller in line. That'll maintain the battery properly and act as a one way so you aren't starting your car from a battery that isn't intended to do a super high current draw like what's needed to start the truck. Also be aware that most starter batteries have a smaller capacity and you don't want to drain it past 50% or else you'll start to damage your battery. Ie a 100ah battery should never be discharged lower than 50ah

[marktaylor]

This looks great and in budget. Almost everything else you watch has a $1000 set up. Thank you for this.

[ApothaconFi]

Thank you man, this is one of my next projects and this made it _a lot_ more straight forward, also the analog aspect of it is very appealing since swapping a fuse or relay is cheaper then replacing a charge controller

[paulscomedyclips]

This instantly went into my "Overland to do list" Thanks!!

[hillebrandstreet]

What a champion I just needed something simple for a long drive and this is perfect excellent video !

[davidbrady]

Cant wait to start my set up….need to free up some room first….but with a 1971 Bronco it should be too hard. Love the channel

[mrbookends]

Stumbled across this video today as I've been contemplating a dual battery setup for my project truck! Subbed and saved - thanks!

[supercoupe]

Thanks Michael. I saved this video to my overland folder. I'm a new Overland Bound member and this video is helpful and answered a few questions I've had about the dual battery setup.

[radnaabaatard]

Thanks for making an awesome video. Actually, I followed up on your relay panel instruction video and built up a nice and reliable relay panel and fusebox in my Landcruiser 78 troopcarrier. Thank you. BTW, greetings from Mongolia.

[wyattoneable]

Thanks Michael. The information in the description box helps and that was a cool diagram.

[marshallnorth]

A few years ago I did something similar. Except with 10 guage wire and a 40 amp relay. I had the relay pickup on a switch.
Worked great. It was a similar setup to old VW camper busses.

[jimmuehlberg]

Nice clean install! I like the simplicity. Since I'm an electrical engineer, I must point out a possible "gotcha". If you drain the house battery, as soon as you turn the ignition on, you will start "charging" the house battery whether or not the engine is running. This will reduce your cranking amps, and if you goof and leave the ignition on without starting, you'll have 2 dead batteries! Solution here is a battery isolator, but that would up your cost and it's solid state, so that goes against your philosophy!

[OverlandBound]

Hey all - thanks for watching! Lot's of great comments and questions. Here is a top Q&A from the community:
1. Improvement: Manually switch your solenoid. If the house battery is completely dead - and you turn on the ignition without starting the vehicle, the batteries will equalize - draining your start battery. To avoid this - manually switch your solenoid and turn it on after your engine is started (contributed by Paul Adams).
2. Overlooked: Both batteries should have the same charging profile since there is not battery manager. I have two identical NorthStar AGMs. Same same.
3. Question: Can I use a stock alternator? Sure - However, if you have a weak alternator - it will not be up to the task, and may fail. I am confident in my OEM Land Cruiser alternator (its new), but I will eventually upgrade.
4. What about a "Smart" Alternator? Smart alternators become an issue with DC to DC chargers. They don't see a enough voltage to turn on so you need the small sensing wire to tell the charger to start charging the house battery. (contributed by Hillbillyjeeper WV)
5. Does this setup allow you to jump start your self by connecting the batteries if the starting one dies for some reason? Theoretically yes, but likely your house battery will be more drained. But yes. Also, see note above about Battery Equalization (1)
6. Can I put my house battery in the rear of the truck? Not recommended - you start getting into battery manager territory there - not really intended for this simple setup.

[ThaiRoney]

Great video! I didn’t understand how the solenoid worked before watching this video, now I totally get it! Thank you! Great skills