Mazdarian

iTrader: (1)

Hi all,

I'm planning on relocating my battery to the trunk spare tire well, along with an enclosure and a 100A circuit breaker, to remove yet another eyesore from the engine bay. Anyone done this before? Any tips / pointers / pitfalls pointed out would be greatly appreciated

Car's an '86 N/A, bridged, MS3Pro EVO in the works, battery undecided - anything that would fit the needs of the car AND the space in the spare tire well, something like below..

Cheers!

mazdaverx713b

iTrader: (91)

I've never seen that done personally. Most people relocate the battery to the storage bin if they are doing a battery relocation. You may need to fabricate a small shelf so that the battery will rest flat and find a way to secure it, as there is not much room back there. I don't see why it wouldn't work, just a lot of battery cable to run.

Mazdarian

iTrader: (1)

Yes well my car's actually got a back seat of sorts; big enough for a backpack and a couple of cold ones but no hatches for a battery 🤷

clokker

iTrader: (2)

I relocated the battery to the more traditional bin location and used a cutoff switch similar to what you've shown.
This puts the switch within reach of the driver and makes for a useful immobilizer but I understand how that's not an option for you.

No matter where you site the battery, the primary concerns will be using cabling of a suitable gauge (I used welding cable) and proper routing.
Make sure to grommet any/all pass through holes and securely hold the cable in place.

Mazdarian

iTrader: (1)

Hey Clokker,

Thx for that 😌 I think i've got some 10awg wire in stock, might be enough? About the cut-off, I'd already planned one reachable in the dash, and maybe an external one near the windshield if trackdays become a thing.

Routing the wires; either one of the door sills? Or along the center console? I already have audio wires running along the passenger sill, think the battery might interfere with those signals..

clokker

iTrader: (2)

The wire path kinda depends on where it begins in the bay, where it passes through the firewall and where the battery is located.
Determine those three and the routing becomes more obvious.

Greener

10 gauge is far too small for the length of wire you will need. I’d recommend either 1/0 or 2/0.

Also highly recommend these for the firewall. Heavy Duty Battery Feed Studs - Cole Hersee

Mazdarian

iTrader: (1)

Hey Greener,

I checked the thiccest cable we have around, and it proves to be 1/0, thanks for the heads up. Those bulkhead connectors are awesome btw, really clean install using those 😯

clokker

iTrader: (2)

Indeed but bear in mind that every break in the cable is a voltage drop.
Maybe not significant or even a problem, but worth avoiding if at all possible.
Before going to the trouble and expense, see if there are any unused/suitable holes already in the firewall.

Rob XX 7

iTrader: (8)

from the trunk I would do 0 gauge to the terminal under the hood and a separate smaller wire direct to the starter would be nice as well

FührerTüner

iTrader: (5)

2/0awg to 2awg should be fine.

charliebars

the purpose of relocating a battery is to get weight in between the wheels. you moving it way to the back does nothing but move it. its helps nothing

FührerTüner

iTrader: (5)

Dumbest **** I ever read. There are plenty of reasons to relocate the battery such as shifting weight from the front of the car to the rear, and engine bay space.

cone_crushr

iTrader: (18)

While true that @charliebars post is poorly phrased, his point is valid. A better phrasing might be: "The primary performance benefit of relocating the battery is to place it's substantial weight closer to the overall CG, thereby reducing the vehicle polar moment of inertia (i.e. tendency to over or understeer)."

As FT mentioned, there are other benefits as well, but generally relocating the battery to the tail of the a tail-happy car like the FC is a bad idea. Unless you need the space (e.g. for intercooler) I'd recommend against it. Now adding a LiFePo or small Oyssey battery to reduce battery weight is fine, but keeping it near the starter is the way to go.

P.S. I miss Clokker.

GeenIdee

I have removed the spare tire compartment and replaced it with flat floor. Laid down a lithium battery on that spot. If I remember correctly I've used either 30 or 35mm2 cable and I could notice a drop in starter speed.

But it does the job

charliebars

the whole reason rx7s are known for the great handling is the weight distribution, the weight of the car iis between the wheels. real race cars would have battery relocated to back seat area for that reason..

charliebars

You type way too eloquently for the masses, talk to these dummies like a dummy lol

lespaul166

So I am relocating battery to storage bin. The write up I found states use of 2/0 Gauge wire is mandatory. I have a large roll of 1/0 gauge red wire laying around, more than enough to run from battery to engine compartment. 1/0 SHOULD be fine right?

JerryLH3

iTrader: (11)

Yes, 1/0 should be fine. Are you sure people said 2/0 AWG was mandatory and not just 2 AWG? I used 2 AWG and have had no issues and I would guess 2 AWG is a common size to use for that relocation..

FührerTüner

iTrader: (5)

Mandatory for what exactly?