Moving Battery To Rear/Wiring

AssBurns

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#1
So I’ve been meaning to move my battery to the back of the vehicle to get the battery out of the engine bay. I’ve been wanting to do this for a few reasons:
1) My core support is falling apart and won’t be able to last much longer with a heavy ass battery sitting on it.
2) I plan to gut the inner fenders and strengthen the core support area and do an engine cage eventually. It would be nice to not have a battery in the engine bay taking up space.
3) less weight up front is always a benefit.

So here is my question comes in. I hate messing with electrical and prefer to just ask people that are better than me at this for advice.

Routing battery cables to the rear. Should I just get as heavy gauge cable to do this? (Welding cable is fine. 2 gauge?)

Ground. I can just ground the negative to the frame correct?

Battery Disconnect. Seems important to have along with a circuit breaker since the cables will be so much longer and more potential for issues. What size breaker should I use? 100A?

Winch Cables. Think the winch cables need to be routed to the battery or will a buss bar in the engine bay be good enough?

Battery. I’m thinking a sealed AGM due to lack of fumes and need for venting. Now here is another question that is relevant but can also potentially be its own thread.

I plan to eventually get a fridge and would really like to avoid dual batteries if I can. For weight and space savings. Should I get a deep cycle (marine battery) or a standard starting battery? I don’t plan on running a lot of equipment off of it besides a fridge. Sometimes I play music from the vehicle when we are out but rarely for long periods of time.

Thoughts? Questions? Concerns?
 
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#2
I would just run a huge ass positive and negative to the engine bay and have like terminal posts there that are essentially where the battery used to be (so everything just plugs back to that like it's stock location). Personally I would run a ground wire all the way over and not just rely on the frame. Can you ground off the frame? Sure, but personally I prefer to run all my high current loads direct to the battery (or the engine bay posts).

I ran a 100A fuse iirc and that had 100% of the vehicle's electrical system running through it. Winch, starter, lights, ignition, everything. Maybe it was 150A, idk, it never blew though. Also remember for your main power cut off you need it to isolate the battery and the alternator together, since just cutting the battery off obviously doesn't do anything if the truck is running.

And personally, I wouldn't mount the battery inside, sounds annoying imo when you have the entire stock spare tire carrier area to tuck a battery up. I guess if you have a bunch of storage stuff and don't plan to ever move it it doesn't really matter, but just having a huge ass battery sitting where you have dogs and people and tools and shit always moving around doesn't appeal to me.
 

4runner DOA

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#3
Here's a couple thoughts based on what I've got running, although I'm neither an electrician nor do I have my battery in the rear.

With my dual battery setup I'm running 1/0 gauge fused at 200a to connect the batteries with a 200a isolator. The 1/0 is gauged at like 250a I believe so I'll blow a fuse or the isolator before I burn the rig up. I'm also running 1/0 gauge to the cargo area to a 100a fuse panel. That handles my rear lights, fridge, and ARB single compressor. The longer the run the bigger the gauge so you have less drop off. I originally had 4g running to the rear and it just couldn't keep up with the fridge running. I basically over killed the entire setup for voltage drop off and risk of fire since I run my ground/power for the rear along the frame.
 

AssBurns

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#4
I would just run a huge ass positive and negative to the engine bay and have like terminal posts there that are essentially where the battery used to be (so everything just plugs back to that like it's stock location). Personally I would run a ground wire all the way over and not just rely on the frame. Can you ground off the frame? Sure, but personally I prefer to run all my high current loads direct to the battery (or the engine bay posts).

I ran a 100A fuse iirc and that had 100% of the vehicle's electrical system running through it. Winch, starter, lights, ignition, everything. Maybe it was 150A, idk, it never blew though. Also remember for your main power cut off you need it to isolate the battery and the alternator together, since just cutting the battery off obviously doesn't do anything if the truck is running.

And personally, I wouldn't mount the battery inside, sounds annoying imo when you have the entire stock spare tire carrier area to tuck a battery up. I guess if you have a bunch of storage stuff and don't plan to ever move it it doesn't really matter, but just having a huge ass battery sitting where you have dogs and people and tools and shit always moving around doesn't appeal to me.
For the ground, wouldn't the frame be like a huge ass conductor anyways? It almost seems like it would be better than another cable. I really don't know though, that's why I'm asking these questions. Running a 2nd cable wouldn't be an issue, but only if it's a better way to go.

Let me know what size breaker you actually have. I don't need any guessing. :flipoff:

For the disconnect, it would be fine to just have a breaker at the battery, then a disconnect in the engine bay at the alternator/battery cables?

I no longer have the stock spare tire location to tuck a battery up into. It's got a fuel tank sitting there now. I might able to tuck a battery between the 4 links, but there might not me much room. I'd have to really check and measure. My plan is to build a storage box in the rear cargo area, and build the battery box into that behind the back seats, so it's completely out of the way from day to day stuff.

Here's a couple thoughts based on what I've got running, although I'm neither an electrician nor do I have my battery in the rear.

With my dual battery setup I'm running 1/0 gauge fused at 200a to connect the batteries with a 200a isolator. The 1/0 is gauged at like 250a I believe so I'll blow a fuse or the isolator before I burn the rig up. I'm also running 1/0 gauge to the cargo area to a 100a fuse panel. That handles my rear lights, fridge, and ARB single compressor. The longer the run the bigger the gauge so you have less drop off. I originally had 4g running to the rear and it just couldn't keep up with the fridge running. I basically over killed the entire setup for voltage drop off and risk of fire since I run my ground/power for the rear along the frame.
Good to know. Might just be better to get heavier wire, even if not completely necessary. A 2nd fuse panel would be pretty nice to have in the rear as well for lights and fridge. Luckily the fridge would be next to the battery when it's all done, so that would be pretty simple to run lighter gauge to the 2nd fuse panel in the rear. But heavier gauge never hurts to have.
 
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#5
For the ground, wouldn't the frame be like a huge ass conductor anyways? It almost seems like it would be better than another cable. I really don't know though, that's why I'm asking these questions. Running a 2nd cable wouldn't be an issue, but only if it's a better way to go.

Let me know what size breaker you actually have. I don't need any guessing. :flipoff:

For the disconnect, it would be fine to just have a breaker at the battery, then a disconnect in the engine bay at the alternator/battery cables?

I no longer have the stock spare tire location to tuck a battery up into. It's got a fuel tank sitting there now. I might able to tuck a battery between the 4 links, but there might not me much room. I'd have to really check and measure. My plan is to build a storage box in the rear cargo area, and build the battery box into that behind the back seats, so it's completely out of the way from day to day stuff.
Yea, I'm no electrical engineer but you're correct. But there's also lots of stuff that wires straight to the battery instead of going through the chassis even though the chassis would be a lot more convenient, that's my only reason (maybe on the buggy I'll just ground the winch straight to the chassis and see if there's any issues).

For the disconnect, yea that would be fine, I guess the question is what do you want to do? Do you want a master kill switch, or do you just want a battery disconnect? If you just have a battery disconnect, then put that with the battery or where ever and call it good. If you want to be able to fully kill the truck, have the battery and alternator go to one side of the kill switch, and then your hot wire (that goes to the engine bay most likely, and everything attaches to) come off the other side.

I wasn't sure how your fuel setup was done, so I see your predicament. As long as it's a sealed battery the inside has no issue, I just know having a subwoofer gets in the way enough times and needs to be pulled out for more room periodically but if you had that same issue with the battery, well you're kind of SOL about moving it anywhere unless you have a huge wire loom for the battery so you can kind of move it around the cabin a bit. Food for thought. My Optima red top is really compact compared to any other battery I've had, and it cranks harder and longer it seems like than any other battery I've had, not to market Optima but point being you might not need as big a battery as you think (or run twin slightly smaller batteries that hug your fuel tank or something?). Idk.
 

AssBurns

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#6
Yea, I'm no electrical engineer but you're correct. But there's also lots of stuff that wires straight to the battery instead of going through the chassis even though the chassis would be a lot more convenient, that's my only reason (maybe on the buggy I'll just ground the winch straight to the chassis and see if there's any issues).

For the disconnect, yea that would be fine, I guess the question is what do you want to do? Do you want a master kill switch, or do you just want a battery disconnect? If you just have a battery disconnect, then put that with the battery or where ever and call it good. If you want to be able to fully kill the truck, have the battery and alternator go to one side of the kill switch, and then your hot wire (that goes to the engine bay most likely, and everything attaches to) come off the other side.

I wasn't sure how your fuel setup was done, so I see your predicament. As long as it's a sealed battery the inside has no issue, I just know having a subwoofer gets in the way enough times and needs to be pulled out for more room periodically but if you had that same issue with the battery, well you're kind of SOL about moving it anywhere unless you have a huge wire loom for the battery so you can kind of move it around the cabin a bit. Food for thought. My Optima red top is really compact compared to any other battery I've had, and it cranks harder and longer it seems like than any other battery I've had, not to market Optima but point being you might not need as big a battery as you think (or run twin slightly smaller batteries that hug your fuel tank or something?). Idk.
I guess I'll have to do more searching on using the frame as a ground. I'd think it's better, but I'm a noob at electrical stuff.

I think it would be a good idea to have a master kill switch, but it's kind of a waste for it to be under the hood. So either wire it to be in the cab within reach or just do a battery disconnect. Something to think about for me as I do the wiring.

I know it could be in the way with it in the cab, but I'm hoping with it tucked into the cargo box, it won't be as noticeable. Twin smaller batteries could be pretty cool. I'll look into that some more. I bet I could tuck some small batteries between the links somehow.
 

4runner DOA

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#7
Wouldn't it just be easier to redo all your core supports to handle the abuse vs redoing your entire electrical system?
 
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#8
Wouldn't it just be easier to redo all your core supports to handle the abuse vs redoing your entire electrical system?
I was thinking he said he wants to do an engine cage, unless space is really really tight just do a fabricated battery box off a frame post as a temporary solution until the engine cage and that'll hold everything great.

Also personally, if you're gonna rewire everything through the cab I would probably do the master kill switch, that's not that much more wire than you'll have already and even though it's not needed I think it's a cool safety feature to have. I know on the 4500 car I had something short out at one of the pits, and it wasn't a fused line and it didn't draw enough power to trip the master fuse so started smoking. Flip the master kill and all power to everything is gone. Not like you can get a weird short and have it start smoking and just stand there and wait to put out a fire or have to wrestle the power off the battery to stop the short. Also would be convenient for working on the truck since you don't need to unplug the battery, you just turn a knob. Food for thought.
 

AssBurns

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#9
Wouldn't it just be easier to redo all your core supports to handle the abuse vs redoing your entire electrical system?
Yes and no. Yes it would if I were to just be putting back to the way it is, but I plan to do a few more things in the long run that would benefit with the battery out of there.
I may eventually go to 37's down the line, and want to keep as much up travel as possible, so moving the wheel forward and tubbing the whole inner fender/wheel well will be necessary and the battery is already taking up a lot of precious space for that to happen. Sure I can keep the battery there and move it or run something smaller, but that ends up being almost the same amount of work.
With an engine cage, it will get extremely cluttered in the engine bay and I'd rather just ditch everything that's not necessary.
Weight distribution will also be a bonus with all this. Right now the front end is MUCH heavier than the rear, so any little bit to counter act that will be a benefit.


I was thinking he said he wants to do an engine cage, unless space is really really tight just do a fabricated battery box off a frame post as a temporary solution until the engine cage and that'll hold everything great.

Also personally, if you're gonna rewire everything through the cab I would probably do the master kill switch, that's not that much more wire than you'll have already and even though it's not needed I think it's a cool safety feature to have. I know on the 4500 car I had something short out at one of the pits, and it wasn't a fused line and it didn't draw enough power to trip the master fuse so started smoking. Flip the master kill and all power to everything is gone. Not like you can get a weird short and have it start smoking and just stand there and wait to put out a fire or have to wrestle the power off the battery to stop the short. Also would be convenient for working on the truck since you don't need to unplug the battery, you just turn a knob. Food for thought.
Yeah I've actually had this issue before where the battery cables grounded out on the way to the starter and caught fire and melted everything. I had to pop the hood and rip off the battery terminals and burnt the shit outta my fingers. An in-cab kill switch would be very convenient and safe. I really like that idea for working on the rig too.
 

Dukestaco

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#10
Let's
I would just run a huge ass positive and negative to the engine bay and have like terminal posts there that are essentially where the battery used to be (so everything just plugs back to that like it's stock location). Personally I would run a ground wire all the way over and not just rely on the frame. Can you ground off the frame? Sure, but personally I prefer to run all my high current loads direct to the battery (or the engine bay posts).

I ran a 100A fuse iirc and that had 100% of the vehicle's electrical system running through it. Winch, starter, lights, ignition, everything. Maybe it was 150A, idk, it never blew though. Also remember for your main power cut off you need it to isolate the battery and the alternator together, since just cutting the battery off obviously doesn't do anything if the truck is running.

And personally, I wouldn't mount the battery inside, sounds annoying imo when you have the entire stock spare tire carrier area to tuck a battery up. I guess if you have a bunch of storage stuff and don't plan to ever move it it doesn't really matter, but just having a huge ass battery sitting where you have dogs and people and tools and shit always moving around doesn't appeal to me.
Let's not forget gas. Batteries release a small amount of hidrogen gas when charging. It only becomes dangetwhen in side a small space like the interior of a car and it has to be 4% or greater to become explosive. I wonder how long that will take in a 4runner? Just saying
 

AssBurns

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#11
Let's
Let's not forget gas. Batteries release a small amount of hidrogen gas when charging. It only becomes dangetwhen in side a small space like the interior of a car and it has to be 4% or greater to become explosive. I wonder how long that will take in a 4runner? Just saying
I thought sealed AGM batteries don't have that issue?
 
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#14
On those heavy gauges I’m sure y’all know the connections should be crimped, soldered and heat shrink. I use my vise and a punch, because I haven’t a crimper that big. I really like the kill switch in cab, maybe do a fuel pump kill too. As for batteries in the cab the sealed types should be fine. Spittballing here, but what about the area under the rear passenger seat, tub the area underneath to fit the battery. Much more out the way. Plus you could build a stash spot and have a great place for all fuse box and electrical dodads. This cuts down on wire lengths and makes for easier future wiring. Just my .02
 

AssBurns

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#15
On those heavy gauges I’m sure y’all know the connections should be crimped, soldered and heat shrink. I use my vise and a punch, because I haven’t a crimper that big. I really like the kill switch in cab, maybe do a fuel pump kill too. As for batteries in the cab the sealed types should be fine. Spittballing here, but what about the area under the rear passenger seat, tub the area underneath to fit the battery. Much more out the way. Plus you could build a stash spot and have a great place for all fuse box and electrical dodads. This cuts down on wire lengths and makes for easier future wiring. Just my .02
I've always use large pliers to crimp the terminals, but I think a punch may be a better idea. Or I could just get a large tool to do the job...

The problem with that is that my upper links already touch the floor under the seat at full bump, so no way I'd be able to stuff a battery in there. It would be cool though. Might be a decent place for a fuse box though!
 
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#19
I've always use large pliers to crimp the terminals, but I think a punch may be a better idea. Or I could just get a large tool to do the job...

The problem with that is that my upper links already touch the floor under the seat at full bump, so no way I'd be able to stuff a battery in there. It would be cool though. Might be a decent place for a fuse box though!
I haven’t seen your rig and I know you’re well beyond my fab skills, but I imagine your links favor either the middle or the outside part of your frame. There’s no space to drop down 8+ inches and allow the gap between seat and floor to take up the rest? Can’t wait to see what you finalize on! That’s so much mods!!
 

AssBurns

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#20
I haven’t seen your rig and I know you’re well beyond my fab skills, but I imagine your links favor either the middle or the outside part of your frame. There’s no space to drop down 8+ inches and allow the gap between seat and floor to take up the rest? Can’t wait to see what you finalize on! That’s so much mods!!
There might be just enough room in front of the coil buckets where the bend of the frame is on the drivers side but I kind of doubt it. With my links being double triangulated, it takes up a ton of space. Especially with the up travel I have. The bottom links are above the bottom of the frame rails at full bump. I’ll try to measure and take a picture tomorrow to see what I can do. The tallest part of the frame rail is also only 5.5” tall, so either way a battery will be hanging below the frame wherever it could fit.
 

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