Secondary Battery Location

I'm adding a secondary lithium battery to my Tacoma. I'm thinking of placing it either in the bed above the wheel arch, beneath the bed (fully recessed into the bed structural ribs), or behind/under the seats. I have a fair amount of freedom in the batterie's shape.

The charger and cells are high efficiency. Under/behind the seat would be very convenient, I'm concerned about how to penetrate the cable out from that area without cutting or drilling.

 

Since it is lithium, I'd think you'd want it in the cab to help keep it from freezing. Assuming you also have a BMS that will keep it from charging when it's too cold inside or outside your vehicle.

How big of cabling are you going to be running for it? Depending on how large it is drilling might be mandatory.

 

I thought there were decent sized plugs on the underside of the body floor. Crawl under there and see if any go up to the cabs carpet.

 

The BMS does have under/over temperature protection. I believe LiFePO4 batteries are fine to freeze, as long as you do not charge while they are frozen?

I'm planning to run 8AWG wire to the car's electrical system for charging. There are penetrators to get into the cab, I used them when installing an electric tailgate lock. I'm hoping to place the batteries behind/under the rears seats, I don't see an easy way to run and cover wires into there.

2AWG wire to my inverter, which will be near the battery (in cab or not).

 

8g under the carpet to one of the plugs?

Same technique as the tailgate lock. Just go further up the carpet.

 

I'm thinking of running the wires like this so that I do not have to cut. Has anyone removed the back plastic cover? It looks like there might be a nice way to run them behind it.

 

I forgot to post the update on this project. I boxed up the battery and added a 12v/light/usb/rear dashcam setup to the bed.

 

Looks good! Where did you get the recessed cubby panel?

 

if you remove the backseat tray a 100ah SOK heated battery will fit back there, its in a big steel case but if you aren't worried about cold you could fit some of the smaller 100ah batteries to get 200ah behind there without impacting the use of the rear seat

 

It is homemade: lasercut panel with painted text, 3d printed case.

It's super interesting that you mention this. I would not build a custom pack again. It is a PITA. From a cold perspective, I've in some decently chilly nights of around 10F and the battery's thermal cutoff for charging hasn't tripped. This pack is about 1.4kwh.

 

precisely why i got the SOK, the case is a tank and has the heating elements wedged between the cells already.
it can take several hours of freezing temps to remove the heat from the cab, unless its been sitting for a while.
if the evening started with temps in the 20s, that is a night the thermal protection will probably trip.
There is also some heat generated from drawing power too

 

I had an issue of stuff like large boxes hitting my rear facing camera that was sticking down like that when I mounted it on an extension - but I found that 3M tape is very good at mounting it directly to the glass on the rear shell door - even when the glass gets hot from direct sun. Of course you will need extra slack on the cable and a mount that will allow the camera to be set against the glass like that or fab a custom one.

 

Are there any threads on TW about people using the SOK 100AH as the sole, primary starter battery, i.e. as replacement for the stock SLA or AGM battery? Searching but haven't found any so far.

Dakota Lithium & Battleborn make replacements for this purpose but they're ~$1,000 or so. I'm wondering if a 100 AH SOK at ~$600 would work just as well, and I like that SOK batteries are designed to be fully serviceable.

 

Where are you running the negative cable to of the second battery?

 

There is a common ground. I've got 4AWG to the starter battery with a sepperate fuse on the positive under the hood. Everything meets at a fusebox on the battery.

 

I was doing the same, which common ground did you use? Frame or Block?

 

At the frame connection near the battery. Sorry for the edits I just checked my setup.

 

My second battery is going into the box. It’s a long run for a ground for shorting reasons. Im still debating the best spot for ground

 

Hey! Sorry I just edited my post. I tie to the frame ground near the battery. I ran the wires underneath the chassis in a double layer of plastic wire loom with a positive side fuse near the battery.

 

Little trimming and a 100ah fits.