Affordable Dual Battery Setup Using DC-DC Charger-Easy DIY

We show all the details on how to install it, along with all the parts needed for a state-of-the-art dual battery system that's affordable and easy to install. By doing the install on your own and saving money where you can, you can have a super reliable power source for your automotive fridge, camping lights, whatever makes your overlanding experience pleasurable.
In the video we show the cost of the materials, (as of 3/13/2021), as well as provide links to them below. The overland power system we show costs less than a typical dual battery kit.
The DC-DC charger we use is a CTEK D250SE. In the video we show how to make all the wire connections and how we mounted it. We also explain why a dc-dc charger is best for charging an AGM battery like our Optima DH6 Yellow Top.
We installed ours in a Toyota FJ Cruiser, but this DIY auxiliary battery system can be adapted to fit just about any SUV, Jeep, Subaru, or pickup truck.
Here are the battery terminals: sdhqoffroad.co...
Here are the Amazon Affiliate links to the vast majority of the parts we used in the install:
CTEK D250SE, Dual Input, 20A, DC-DC Charger: amzn.to/2NdVJvu
Optima DH6 YellowTop Dual Purpose Sealed AGM Battery: amzn.to/3qO5w9k
Inexpensive, Universal Battery Tray: amzn.to/3voTbfd
Inline Fuses, 10awg, Three Pack: amzn.to/2OOgsXd
10awg Wire, Black & Red, 10' Long: amzn.to/3tlNQnj
Thermal Circuit Breaker, 30 amp: amzn.to/2Os8F1v
Thermal Circuit Breaker, 40 amp: amzn.to/2Q4ucxT
Braided Wire Sleeving, 3/8" x 25': amzn.to/3voF7Co
Plug-in & wire for solar panel connection, 10awg, SAE: amzn.to/3bISx4w

[@ezza88ster]

What a great and clear video. Even including how you can go higher spec or lower spec and stay safe at the same time. Great work ! Thanks.

[@WanderlostOverland]

Glad you liked it!

[@graphicventures]

Hi, just a suggestion. the sensor could be insulated with some foam and then taped - this would give the actual batt temp instead of the engine bay temp.

[@dimascuevas5834]

You two make great videos. I really enjoy your channel. Thank you for taking the time to make them.

[@WanderlostOverland]

Thanks for watching!

[@andsoitgoes2177]

I love how your wife acts like she's on the Home Shopping Network. Hilarious. Unless that was unintentional. In which case, hilarious.

[@alexblaze8878]

Reminds me of the “Black Caulk” episode from Mad TV

[@markallen9389]

Can I install a power inverter with this system and would it be just as simple as installing a power and ground to the inverter off of the CTEK with the correct AWG and breaker? Great video very informative!

[@jasolr1135]

High quality video instruction. Nice.

[@WanderlostOverland]

Thanks!

[@johnr5545]

Thanks god bless

[@OffroadGrind]

Great video. So much great info

[@WanderlostOverland]

Glad it was helpful!

[@jasondelacruz5331]

so good, always include outtakes please!

[@dennissecor8092]

Hreat video, but a little closer view of the items you used would help though and i dont see any links?

[@WanderlostOverland]

The links are in the video description.

[@jeepncj7]

Does the 2007 FJ have a smart alternator? Curious as I have the CTEK on my 2007 4runner with the same 4.0 and I was told it did not.

[@wildherring3988]

Strong work

[@WanderlostOverland]

Thanks!

[@jeffbrown1776]

Maybe a dumb question, but, is the alternator charging the charger that charges the deep cycle battery? 🙂

[@WanderlostOverland]

Yes

[@jeffbrown1776]

@@WanderlostOverland Thank you.

[@grumpyshorts1056]

So with this setup... no isolator is needed! Hmmm, you may have just changed my mind! :-) Gotta compare the CTEK to Renogy 20A DC to DC Battery Charger $100 cheaper!

[@MrLesliedavidson]

CAn I use the ctek for my ram truck ?

[@WanderlostOverland]

Of course.

[@richk4452]

What made you use the CTEK this time over the REDARC you used in your other rig ?

[@WanderlostOverland]

Just wanted to try something different.

[@adventureoverland9199]

Appreciate you guys going into full detail for a fj dual battery set up. No one else has done a great detailed video like this yet!

[@WanderlostOverland]

Much appreciated!

[@Tactical-Black]

This was very informative, but im trying to find one on adding an inverter with battery setup for my work van to power my chargers and occasionally a chipping hammer (large load) im thinking of using a battery from batteries r us from golf carts (deep cycle) Thinking of putting a breaker and then a fuse to a battery charger (charge controller)to limit the cable size, with an automatic disconnect or VSR (voltage sensing relay) to turn it off and on Any ideals? Or is this overkill

[@ltbomb7194]

That whole thing is overkill, mostly the price. But i do commend you both for a great video you guys did. Not many people know how difficult it is to make these videos, the time and effort you put into them. Keep them up. You both were great and informative

[@nightflyr1]

Interesting setup. One thing though.... I run dual batteries (matching optima AGM ) one under the hood the other behind the rear seat. Both are charged off the 120A alternator. The setup costs are: the batteries total $560.00, Stinger 200A isolator $54.00, assorted fuses $30.00, terminals $10.00, a set of 6 gauge 15 foot jumper cables $50.00. Total cost for a complete system with 2 new AGM batteries $704.00 The primary via the factory setup, the secondary is controlled by a pair of relays wired into a Stinger 200A isolator and both batteries are fused. At startup, both batteries are tied in series to assist with starting the engine and while the engine is running both batteries are being charged. With the key off, both batteries are isolated, so as to never draw off the primary start battery. All electrical accessories are wired off the secondary battery. I'll be going into my 10th year with this setup. Not sure what the life expedience is going to be for the batteries, but I'm pretty sure they must be coming to the end.

[@stevegreen245]

Sweet, finally a simple dc to DC system. I've put it off cuz of the complicated systems out there. I like straight forward. I'm not good with electronic stuff. But I can do this one. Being how you did all the work already.

[@johndiaz7240]

Great info , we have been using CTEC for 4years and love it in our FJ Cruiser and our FJ 60 . We mounted the unit inside the cab in the 60 because to much heat under the hood . We use a Goal Zero 500 Lithium when we camp in our FJ40 for frig and camp lights . We have enjoyed your videos for years thanks.

[@shalamigri]

That's an Optima Yellow top. Isn't meant to be used as a starting and/or a deep cycle battery (dual purpose battery)? I heard a saying that goes, "When in doubt, use yellow top." I gotta say though. This is probably the best wiring job I've seen. I like how you mounted the charger and breakers on the auxiliary battery. Nice work!!!

[@RoamRoadless]

Why not just hook it up to a solenoid, so it doesn’t drain the starter battery when the cars off. This system is nice but could be done for $200 total

[@MarkJacksonGaming]

-- Not how I did it, and I wouldn't. But, I'm not looking down at my nose at you. For starters, I use a smart isolator grounded to the negative primary battery post. Solves your smart alternator problem in most models. Second, testing with a voltmeter for a smart alternator, and also model and observation makes it easy to tell. Third, unwritten rule, but one I learned well in 4 years of being a car audio installer (remote starts, amps, caps, head units, etc) with something like this, use 4 gauge wire. Fourth, double ground both the primary and aux batts. Fifth: You probably did it later, but electric grease on those connections. And your breakers are a little lite. I'd go 50 primary, 60 secondary batt. Lastly, you need an easy plan if your primary battery crashes. Not sure the charger you're using can do that, but it means dual grounds and a quick disconnect so the secondary battery can operate the vehicle by itself. But I'm glad you mentioned you want those breakers as close to the batteries as possible; that's critical. A very nice, clean install you have there. Suppose if I had anything to add to people interested in doing this for the first time, it'd be spend time looking under your hood, and have a plan. Work backwards from the secondary batt, then backwards from the primary batt. Last thing that goes in, is the linkage. Thumbs up.

[@kennethBrodt]

Can I replace my UPS battery with a lithium battery 100ah for more capacity? I have a 600 watts UPS in which I have my computer, 2 monitors and the router plug in. Can I use that type of battery ( lithium battery 100ah and can it be charge by the UPS) Thank you for your time and assistance!

[@MrLesliedavidson]

Great video people :-) where can I buy all the stuff I am trying to purchase stuff on Amazon and it’s telling me no dice in my area do you have any other suggestions Home Depot?

[@jefsel881]

Don't for get to double your cable length when sizing. A 15 foot destination is really a 30' run.

[@jonathankuhn2180]

I subscribed not only because it was a great video, but that you asked in a traditional fashion at the end of an informative video. It is so trashy and beggy when people do the automated cgi like and subscribe 30 seconds into their video before I even know if the content is quality or not.

[@andsoitgoes2177]

Very helpful. The most confusing part of the wiring is how to wire the dc breakers. In particular the breaker after the dc-dc charger. You have the Charger outputting to the breaker Battery Line terminal and the breaker Load terminal outputting to the "House" battery. I'm assuming this is correct, since normally the Battery Line is the input side and Load is usually the out side of the breaker.

[@eugenioguerra5958]

Hi guys I watched this video few times, and I have a question: You have to use the Ctek smart pass and the DC to DC together? Or I can use the smart pass alone?

[@corin164]

A wiring diagram or a link to a wiring diagram would have been nice.

[@Concertto]

$321 for just the charger ain't cheap. You can have a dual battery charging system, just as easy to setup and for a lot less.

[@sonnyrodriguez2016]

why can't you use lipo4 12v 100 amp battery instead of optima battery some of them cheaper than optima battery

[@skipwilliams5804]

This is good info. How do you control all your accessories? I want to add a switchpros 9100. Any thoughts?

[@Ted...youtubee]

No association. Have you seen this? On dual lithium battery. kzbin.info/www/bejne/aqOcZ3aIos5-qNU

[@MrLesliedavidson]

Question if you could please help do I still need a battery isolator it’s going to install a Renagee 30 amp dc to dc charger

[@jwat2396]

I only deal with jeeps so I don't know how to adapt this system to my jeep. Thanks for the info though.

[@PaulMessner]

Watched this a few times now. Eagerly waiting the next instalment. Any idea when it will be released? Thank you

[@WanderlostOverland]

Thanks for watching! The video where we make and install the outlet in the back will be released next Sunday afternoon.

[@chrislee4946]

Really considered this system but went with redarc from SDHQ after I saw it on your 4 runner! Do you like this one better than the Redarc? As always love the content

[@WanderlostOverland]

The Redarc is a great choice. We are having tremendous success with the one in our 4R. We just wanted to try something different with this one.

[@AZsmoothrider]

If you have a GMT400 product the 2nd battery space and tray are already there! Boom!

[@brucetripp3331]

Hi if you have an old 1993 car do you still need to run the red wire to your ignition

[@Jibkid]

Have you had any issues with the charger so far? I installed the exact same setup in my Hilux in February. A couple of days ago it stopped working. I'm afraid it just gets too hot under the hood and stops charging...?

[@WanderlostOverland]

No problems at all with it.

[@gaj9080]

Please wear safety glasses when working around batteries. Take it from someone who knows.

[@mangeload]

mostly only when lead acid is charging do they pose a threat. Use ventilation when indoors too.

[@AdrianReddington]

What brand is the "expensive" battery tray you used?

[@easyguitarlessonsgrandpaal9126]

You two did and excellent job explaining DC-DC set up/installation....this is the perfect set up for what I am trying to accomplish....cheers.

[@WanderlostOverland]

Glad it was helpful!

[@jammy93981]

I see you have installed this CTEK and also a Red Arc.. Which one do u prefer?

[@WanderlostOverland]

Both work the same, both are reliable. The Ctek is usually less expensive but the Redarc has a lower profile.

[@janvanderlinde3039]

not normall prises !!! for agm an dc to dc charger

[@alexholloway6404]

CTEK 250SA and SmartPass 120 have been nothing more than optimal, extremely efficient and dependable in my 5th gen 4Runner for over 4 years now. Along with the SwitchPros 9100 and Victron Smart Shunt, I've been able to keep tabs on all my electrical devices and draws. Because of the SmartPass 120, I went with a full 1/0 gauge or 0 AWG wiring size to keep everything cool and juice running clean. Thanks again for all your great videos!

[@WanderlostOverland]

Great to hear Alex! We too are using the Smart Shunt in the 4Runner. For the FJ we're going to test out a cheaper one. I hope we don't "get what we paid for" with it. LOL

[@reidmartin3479]

Hey there! Is you’re guys starter battery leaf acid? And did you use a battery isolator?

[@WanderlostOverland]

In our opinion, starter batteries should always be lead/acid. No need for a battery isolator with our setups.

[@TopNoTchVSOP]

Looks real clean guys thanks for the inspirational tutorial. I too am working on a dual battery setup for my Jeep.

[@christbland]

If the main battery dies, will the house battery fill in for a jump start?

[@WanderlostOverland]

In the case of an emergency it would. I wouldn't make a habit of it though.

[@Bluto4r]

Ive enjoyed your videos. Good info, presented very well. Putting mine in this weekend. Pretty much replicating yours. For the mounting plate, Im using a plastic cutting board from the dollar store.

[@WanderlostOverland]

Glad it helped

[@Bluto4r]

Well, it's in. Thanks to my son, Stan. I'm on an overnight test trip. It's working flawlessly. 😊

[@ricecowboy]

So how would one know what type of alternator is in the vehicle?

[@WanderlostOverland]

If it's newer than 2008 it likely has the modern "smart" alternator.

[@photog1529]

Getting ready to outfit my 4WD Suburban for camping, etc. I notice on one vehicle you're using a Redarc DC-DC charger and a CTEK on the other. Which do you prefer, and why?

[@budcatterton5692]

Great video! I can see how this setup would work good for overlanding as the vehicle is driven most every day. Would it power a 12v fridge while camping for a couple days or would you need to add solar, or is a Jackery type portable power station work better for camping?

[@WanderlostOverland]

There are a lot of variables; temperature, how full the fridge is, etc.. We have run our fridge for a couple days just off the battery. By adding a solar panel you should get more out of it.

[@garycarroll9447]

Can I still use a quick battery terminal off switch with this set up

[@WanderlostOverland]

You sure can. Probably a good idea!

[@AggyGoesOutdoors]

Great video, I see many so called overlanding experts on KZbin who seem to think it's ok just to wire two batteries together with a changeover switch 🤦‍♂️🤷‍♂️ great to see it shown correctly.

[@WanderlostOverland]

Thanks 👍

[@ThisTall]

What’s wrong with doing that wit an isolator?

[@jvinsnes]

Whats your opinion on voltage controlled relays? I bought one that has a photo of a car battery on the front and the description says it’s for adding a secondary battery. Would the batteries be overloaded at the moment it kicks in? One battery at 14.4v and the other at say 11.5? Wouldn’t that be bad for the batteries long term?

[@marvelousrelaxingmusic8667]

Very nice I enjoyed watching 👍422 thank you for sharing 💖 waiting for your visit my friend 😉

[@dwmcever]

Took the money I was gonna spend on a second pickemup truck battery and spent it instead on a 3500watt inverter generator. Never looked back.

[@simon4runner]

thank you guys

[@eltonbull7429]

all is good liked the out takes.

[@richardclause2852]

Thanks guys for info 👍

[@jackas1583]

What do you suggest cheapest way to do this on 2022 F150 xlt? Thanks

[@mayanboricua]

By stealing the components, and/or blackmailing the mechanic.

[@jackas1583]

@@mayanboricua lol

[@FORTRAN4ever]

I had a 1994 Chevy 1500 truck that I ordered with an auxiliary battery and tray. It was positioned on the passenger side next to the firewall. I did use it for camping for lights and a little fan. I had a cap and used it with a tent that connected to the tailgate of the truck. it was really cool. Now I have a turn of the century GMC Yukon that I would like to mount a couple of rigid compact 100 watt solar panels on the luggage rack (which is rarely used) to supply power to a ca. 1200 Watt solar generator in addition to the the vehicle's power system and a 110-120 AC power source. The solar generator is portable to get more flexibility. My main concern is that the solar panels will cause drag which can negatively affect performance and gas mileage on the vehicle. It can be used for camping or bugging out during a SHTF scenario.

[@patrickbuick5459]

Good info. I have a Canadian brand I like, but their stuff isn't waterproof and this needs to be near the batteries. It's an evolution as I'm finding. Taking stuff out as much as adding in!

[@themanleychannel]

lol on those outtakes

[@sailingavocet]

Killer video! Lots of good info here. We may have chatted before but we recently built our own lithium battery bank for our sailboat and would love your feedback :) part 1.5 is on our channel now!

[@jimburke697]

I enjoyed seeing your informative explanations of this modification. I have an 05 tundra {2wd} so it probably doesn't have a smart alternator. I won't be doing any serious overlanding but would like to have an inverter so I can pull a shot of espresso from a 15 amp machine.

[@benjones8977]

My main worry is that with the newer cars there’s so much electronics, unhooking the battery can even cause problems.

[@AZsmoothrider]

Check out NOCO's obd2 port cable if you own any Noco charging products. It's meant to power computer during battery disconnect/maintenance.

[@mangeload]

install the 2nd battery without removing the starter battery, using a dc-dc charge controller connected to the alternator/power source last, after the house battery is connected but do not connect the starting battery until after everything else is connected. The starting battery remains connected the whole time, but only connects to the house battery via the alternator & then the charge controller. The alternators factory settings control the starting battery charge, and the alternators charge get handled & maintained by the dc-dc charge controller.

[@nnperformance76]

Did ur channel get hacked? Today????

[@nnperformance76]

Truth hurts link???

[@farmermike9262]

How difficult finding a wire sizing chart thats accurate!!! Oh, and printable!!!

[@garegardner6782]

This is the best DIY type video I have ever seen

[@WanderlostOverland]

Thanks!!!

[@satbiranand]

Very informative, a well made video, thank you.

[@BeeBeorn]

I have used Ctek D250S ( no smart generator) and D250SE ( for mobile lithiumbattery) for 4 years. Bulletproof. But, the solarinput has a verly slow mppt algorithm. You get more amps in total from an ordinary pwm solar charger. But the dc/dc charging works like a charm. I have it in the tray. Engine heat will reduce charging, as you know,since its temperature compensating. Time will tell.

[@JesseePDX]

I just dropped 1500$ for a solar/generator power source setup to charge my 70AH battery setup for my trailer and I felt down in the dumps for how much I spend. After watching your video I'm confident not cutting corners on cable size and fuses was the smart thing to do... Now I can charge my house battery in the day and run my diesel heater at night

[@EdJZatta]

Where do you get the pre made battery pan.

[@WanderlostOverland]

I believe we got this one from Dirty Parts.

[@Jeffrey-oh8sm]

Great videos!!!!!! Is there any way I could have a copy of that chart?

[@Okierover]

How is your engine that clean? Do you ever drive it?

[@halohalohikers3571]

Very helpful. Does the charger also prevent the main battery from being drained when the vehicle is off?

[@WanderlostOverland]

Yes, when the ignition is shut off the two batteries are completely separated.

[@robertwenzel5517]

Love your videos with the FJ and even watch some of your 4runner videos as well. You said you installed a Group 48 Battery in the FJ. but it seems like a battery tray is hard to find, would a group 24 be sufficient? I have about the same power requirements as you. Keep up the good work, and more FJ content!

[@WanderlostOverland]

A group 24 will do fine. Thanks for watching!

[@wanderlostNW]

After a year now, do you still like this charger? Do you prefer Redarc over Ctek? Any major difference between the two? Thanks so much! Your contents helped me a lot.

[@WanderlostOverland]

No big differences. The Redarc is physically smaller.

[@ninez5740]

I just subscribed for the bloopers. 🤣 No seriously, I just watched the 2019 video with the Redarc charger. Any reason you're updating(that was a great video)?

[@WanderlostOverland]

We're very happy with the Redarc charger we have in the 4R. We just wanted to try something different on the FJ.

[@f.k.6151]

Was just watching your 4Runner video on dual battery. Why didn't you use the same DC-DC charger in the T4R?

[@WanderlostOverland]

We wanted to try out a different charger. So far both chargers are doing equally as well.

[@GX470adventure]

Great video as always!! I have a dual battery set up currently and installed a battery isolator so it won’t drain my main battery. I have everything connected to my coach battery like my fridge and all. I am not wanting to add a solar panel and have been looking at a dc-dc charger. Will I need to remove my isolator?

[@WanderlostOverland]

You won't "have" to remove it. But it won't serve much purpose when using a DC-DC charger.

[@harryplayzrm1982]

What a great video!! I have two questions, when you reed the voltmeter you installed in the back of your car to power all your gear, how much does indicate? 2nd: It would be any difference in how long last a fridge connected to a Yellow Top DH7 battery compared to a Yellow Top D35 series before it drains the battery? Thanks so much for your great videos!!

[@WanderlostOverland]

Thanks for watching! The volt gauge reads around 12.8 when the battery is fully charged. More when the engine is running and there's charging power going into the battery. I don't have an accurate answer to your second question, sorry.

[@stevecrowe176]

What size is the inline blade fuse? How did you determine what size you needed? Thank you for the easy to listen too vid. Cheers

[@WanderlostOverland]

We always size our fuses to what we're powering. If a fridge draws 8amps we use a 10amp fuse. All that is also determined by what the wire, switches, and connectors can handle too.

[@TheBlankenman]

I liked the video even before the bloopers, but those bloopers set it off. Both of you droppin bombs was hilarious. Definitely subscribing the bloopers adds more realism in my opinion. Thanks for the enjoyable videos.

[@WanderlostOverland]

THANK YOU!!!

[@robertlewis7237]

THANK YOU FOR VIDEO

[@WanderlostOverland]

You're welcome

[@rjl110919581]

thank you for your video

[@WanderlostOverland]

Thanks for watching!

[@cic-jakevanddalgeemyers.2739]

Pops did a good job. but I think mama did great with the presentation... thanks 🙏 mom ...you rock.

[@WanderlostOverland]

😊 thank you

[@ltorban]

Thank you for describing your implementation in detail. Are you able to post a wiring diagram?

[@WanderlostOverland]

Sorry, no

[@mastereymaster8180]

Thanks

[@WanderlostOverland]

You're very welcome!!!

[@mr_incredible112]

Very informative, you should use 4 gauge wire for future upgrades. The use of more current and devices being used later on.

[@psychoticmemories2583]

How many hours are you getting on your fridge without the battery charging (vehicle running)?

[@WanderlostOverland]

We get close to 48 hours.

[@rbastardo7751]

Congratulations on this video, is extremely easy to understand you guys, Thanks for doing this video, God bless you all

[@WanderlostOverland]

Thanks for watching!

[@DD-Aerial-Photography]

I'm glad the Illinios barber shops are open now.

[@WanderlostOverland]

Me too!

[@darrenconroy3900]

Great job!!! Love the bloopers.😅

[@TheJustinPham]

Can you link the solar blanket you guys showed please?