Build Easy Auxiliary Lithium Battery for your Crawler

I posted the this is my 304YOTA Build thread as well.

Long story short, my girlfriend is deathly allergic to bee stings, like she’s been told she could have 15-30min to get to a hospital allergic. It got me thinking about communication on the trail outside of Ham. After installing Starlink on my Toyhauler, I figured having a Mini Starlink on a crawler would be a good idea. But how to power it and not drain the starting battery. I’m not a fan of dual LA batteries, and lithium technology has progressed quite a bit, and come down in price.

I have a LiTime 100ah house battery in my Toyhauler that works perfect, so I decided to pick up one of their more advanced Group 24 100ah battery with Bluetooth and Self Heating. The Bluetooth allows for instant monitoring of the battery on you cell phone, so no shunt or Bluetooth module etc. the Heating allows the battery to self heat so that it can charge in below freezing temperatures.

I also picked up their new 40amp DC-DC Charger / Solar Controller, and an AuxBeam Switch Panel to control the accessories.

The DC-DC charger is a very simple hook up. It has 2 inputs and 1 output, all connected with Anderson Connectors. It self activates and switches between Solar or DC, and isolates the Starting Battery, and has a function where it can back charge the Starting Battery if it gets depleted.



I wanted everything to be easily accessible, So I decided to mount everything behind the Passenger seat of my 83’ Pickup. First I laid everything out, then started drilling and cutting.




The back I made a large opening to allow the charger better cooling. The slot allows for the wiring to enter the switch panel from the back.


I used 1/4” RivNuts and 1/2” spacers to mount the panel.


Then made up my 8awg cables and mounted everything up.






Set Battery Type, and the Charger handles the rest from there. No on/off switch needed. When it senses the alternator it switches from solar. If there is no solar it puts itself on standby when the vehicle is not running.

My original plan was to mount the battery under the bed, but I’m glad I decided to mount it in the front of the bed.

A simple battery box attached to the bed with 4 1/4” RivNuts and a lashing strap held the battery firmly in place.



I surrounded the battery, top, bottom and sides with heat shielding. Power and Charge Wires come up through the bed.


For the Starlink mount I went with 1 1/2” Ram Ball mounts. Total for the 3 pieces was pretty expensive, about $100, but I didn’t see any better options. The mount that clips to the Starlink fits it very secure, no fear of it popping off. The extension arm allows for easy positioning of the dish when in camp.




Side not, the Starlink mini has an internal router, so the only thing coming off of it is the 12v 18ga power. Friends said they could connect well over 150’ away.

I also hooked up my ARB Fridge that I bought and never used. The fridge is awesome, I won’t be going back to a cooler.




The end goal is to also have the Stereo and Rock Lights hooked up to it so I can use them non stop and not run down the starting battery.



The app makes for easily monitory the battery. My truck sat Friday night to Sunday morning without starting, and with Starlink running non stop and the fridge set to 24°, the battery only dropped to 48%. With the 4amp charger, it only took about 1 1/2 hours to recharge.

Here is a view of the app screen.

Nice work on the install and wiring.

but I don't see a subwoofer.

I use a small motorcycle battery as an isolated battery setup. cheap smart isolator. Runs my high power camping auto system for a long time, and all the lights and whatnot.

rattle_snake said:

Nice work on the install and wiring.

but I don't see a subwoofer.

I use a small motorcycle battery as an isolated battery setup. cheap smart isolator. Runs my high power camping auto system for a long time, and all the lights and whatnot.

Click to expand...

Oh there’s a sub lol, 2 8’s all Bluetooth.

Cool setup.
Disturbing the peace and quiet. As it should be.

Nice work, I have a similar setup in the XJ.




In fact the charger I have is the same as yours, just rebranded.

As someone who is also dating an "allergic to everything" chick, I'm assuming you have a epi-pen mount somewhere? I have one in a molle pouch next to road flares lol.

Mittnz said:

Nice work, I have a similar setup in the XJ.

In fact the charger I have is the same as yours, just rebranded.

As someone who is also dating an "allergic to everything" chick, I'm assuming you have a epi-pen mount somewhere? I have one in a molle pouch next to road flares lol.

Click to expand...

Yeah, we have 4 Epi Pens, Benadryl, Zyrtec and some other stuff. Her last big reaction was before I met her, so hopefully she's growing out of it lol. A bee sting better not mess up my wheeling trip lol hopefully she doesn't read this

That's a clean setup as well, looks like larger than a 100ah battery.

Diablo169 said:

Yeah, we have 4 Epi Pens, Benadryl, Zyrtec and some other stuff. Her last big reaction was before I met her, so hopefully she's growing out of it lol. A bee sting better not mess up my wheeling trip lol hopefully she doesn't read this

That's a clean setup as well, looks like larger than a 100ah battery.

Click to expand...

It looks like it, but it's not. I paid way too much for it like 3 years ago when I bought the XJ. Lifepo4 battery prices have come so far down now, that it's embarrassing. It's a big plastic enclosure, which I liked, but, if you pull the lid off there's just a wimpy little battery inside. I think I paid like $325 for it years ago, now you can get the same one for $150... (Recertified) 12V 100Ah LiFePO4 Lithium Battery - Bluetooth, Heating, Waterproof

I was wanting to do something like what you guys did but I ended up going a weird round about way

I got a star link, 110v inverter and a jackery style power bank

So it's basically the ghetto hack/modular version of what you guys did

Mine doesn’t really do anything currently. It just sort of always gets charged. I can reverse charge the starting battery (regular lead acid) from it if it is ever dead, but I’d have to manually plug it in if I wanted to run anything off of it.

I have been looking into getting one of these True® Lithium Smart Battery Isolator Efficient Management for Vehicles & UTVs

I don’t think I can use a regular battery isolator if one is lithium, right? So I would need one like this?

Mittnz said:

Mine doesn’t really do anything currently. It just sort of always gets charged. I can reverse charge the starting battery (regular lead acid) from it if it is ever dead, but I’d have to manually plug it in if I wanted to run anything off of it.

I have been looking into getting one of these True® Lithium Smart Battery Isolator Efficient Management for Vehicles & UTVs

I don’t think I can use a regular battery isolator if one is lithium, right? So I would need one like this?

Click to expand...

You don’t want to ever directly connect a lithium battery to a LA, they operate at different voltages and it can be like a direct short. That’s why the LiTime unit, and like yours, needs to be in the middle and act like the charger and isolator.

Diablo169 said:

You don’t want to ever directly connect a lithium battery to a LA, they operate at different voltages and it can be like a direct short. That’s why the LiTime unit, and like yours, needs to be in the middle and act like the charger and isolator.

Click to expand...

What's the issues? I ran one for a bit before going back to dual sealed lead acid

Alternator puts out higher voltage than either battery, when running that is feeding everything. If the alternator is off and the batteries are tied, the lithium will draw itself down trying to feed the SLA, which just converts the excess into heat, but that is limited by the wire connecting them. It'd take a pretty hefty wire to damage the SLA, and in my specific case the SLA could handle a much higher C rate than the lithium, though they were both "100 amp" batteries.

I did have them isolated with a solenoid though, so key off they were decoupled completely.

Couldn't ever figure the actual need for the DC to DC controllers.

Provience said:

Couldn't ever figure the actual need for the DC to DC controllers.

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I have one so my alternator doesn't see an extra 100a of load and cook itself. Lithium is much greedier when charging than SLA or AGM

You can't connect directly to a Lith battery cells, the controller is built in. It controls current in and out.

Unless you build your own batteries.

Provience said:

What's the issues? I ran one for a bit before going back to dual sealed lead acid

Alternator puts out higher voltage than either battery, when running that is feeding everything. If the alternator is off and the batteries are tied, the lithium will draw itself down trying to feed the SLA, which just converts the excess into heat, but that is limited by the wire connecting them. It'd take a pretty hefty wire to damage the SLA, and in my specific case the SLA could handle a much higher C rate than the lithium, though they were both "100 amp" batteries.

I did have them isolated with a solenoid though, so key off they were decoupled completely.

Couldn't ever figure the actual need for the DC to DC controllers.

Click to expand...

I’m guessing the BMS on the lithium battery was kicking in. They may both be around 12v but are totally different animals.