Trunk Battery & Relay Wiring Question


Jan 1, 2003
Visit site
I'm moving the battery and relay to the trunk and I've got a wiring question.

The battery and the starter relay goes into the trunk.

A 1 guage wire will go from the relay to the starter (old style).
A wire will go from the starter position on the ignition switch to the relay.
A 4 guage (correct size?) will go from the battery hot to the fuse box. (Hot lead)

The hot lead from the battery will be directly connected to the alternator wire and voltage regulator. (stuff that is currently connected to the battery side of the starter relay). This will be done in a new fuse panel. (not sure where to put it).

Does this sound right?
Combined with a good hood lock, I think the car would be real hard to hot wire.
Plus, after hiding the engine compartment wiring, it should be real clean.

Any suggestions?

  • Sponsors(?)

Just a suggestion to battery in trunk conversions. Put just the battery in the trunk and add a "kill switch" (aka racecar type) between the battery and the stuff up front.

Great way to kill the power in case of electrical fire and you can perhaps keep the bad guys from taking your toy if the switch is in a hard to find location.

Happy Motoring!



Jan 1, 2003
Visit site
Thanks for the reply 67efivert.

On the hot wire from the battery to the circuit panel. Perhaps 8 guage wire is better? This wire is the main conduit for charging the battery. If I go with a 130amp 3G alternator, what size wire would I need?

Also, I'm planning on bringing the wire from the alternator/Regulator into the fuse breaker box, thru a fuse and then to the battery wire.

Any suggestions on where to put the circuit breaker box? I can't think of any security issues with it. If there is any security issues, I could put it under the hood as it will be locked.



Apr 28, 2005
Relay as in starter relay? I moved my battery and starter relay to the trunk also. Ran 1 gauge wire from the starter post of the relay to the starter and 4 gauge from the post post of the relay to the alternator. I think 4 gauge wire will be fine with the 130A alt. The additional gauge is needed due to the extra length of the wire compared to the stock length with the battery up front. I also extended the I and S wires using 10 gauge wire and ran them back to the solenoid also. I bolted the ground wire to the rear bumper bracket and is doing great. I've heard that if you have a big block car that you need to run a full length ground wire to the front frame rail since it is on a subframe car.

Oh and the 4 gauge wire i used came from a 400watt amplifier kit that i had as an extra. It uses the fine wire strands for less resistance. Just an idea if you haven't purchased the alternator power feed.


Jan 1, 2003
Visit site
Thanks Edbert for the diagram. That's super. It's given me lots of ideas for the relays. I think I'm going to build a panel under the dash for the relays. Good pix.

JBuening: Thanks for the reply. I couldn't see any use for the I wire on the starter relay. Is it used for anything?

Where did everyone put their fuse box?
Thanks a lot.
Thread starter Similar threads Forum Replies Date
91GTstroked Electrical Trunk mounted battery and grounds Fox 5.0 Mustang Tech 2
Rt jam Battery in trunk Fox 5.0 Mustang Tech 1
robsball Electrical 2012 GT Convertible Drain on battery - Suspect Trunk component 2010 - 2014 Specific Tech 0
rd Trunk Mount Battery And Nitrous Bottle Fox 5.0 Mustang Tech 2
screamin gt Trunk Battery Relocation Thoughts SN95 4.6L Mustang Tech 8
nothwoods Trunk Mount Battery Fox 5.0 Mustang Tech 3
FoxMustangLvr Battery Cut-off Switch In Trunk Fox 5.0 Mustang Tech 7
90lxwhite Battery In Trunk To Do Or No? 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 11
f8tlfiveo Electrical Battery Moving To The Trunk Fox 5.0 Mustang Tech 6
billison New battery tray vs trunk relocation Fox 5.0 Mustang Tech 23
6 How to wire a 1 wire alternator with trunk mounted battery Classic Mustang Specific Tech 3
KDK1988GT Hatch/Trunk Mounted Battery Ground Location... Fox 5.0 Mustang Tech 22
RangerJoe Trunk Mounted Battery Fuse Fox 5.0 Mustang Tech 8
mob How do you guys bolt down battery in trunk? 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 11
L Battery in The Trunk Other Auto Tech 0
srtthis trunk mounted batteries Fox 5.0 Mustang Tech 5
68stang351 Battery in the trunk, need cable routing ideas. Classic Mustang Specific Tech 8
gnx547 Question about mounting the battery in the trunk 1994 - 1995 Specific Tech 22
mattmcdan Fuel Cell and Trunk Mount Battery Pics WANTED!!! 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 4
Islandboy33 Pics of trunk and battery holder Classic Mustang Specific Tech 5
Edster Battery in the trunk. Classic Mustang Specific Tech 1
Z Battery in trunk kits?! 1994 - 1995 Specific Tech 1
wyteelx Wiring a trunk mounted battery Fox 5.0 Mustang Tech 14
AquaTeen2004 any good how 2's on mounting battery in trunk? 2005 - 2009 Specific Tech 12
S Trunk mounted Battery Question Classic Mustang Specific Tech 20
S battery question in trunk Classic Mustang Specific Tech 3
3 Trunk Battery- Starter Ground Issue Classic Mustang Specific Tech 10
Busted07 Trunk mount battery with a 1 wire Alternator (Non-EFI) Fox 5.0 Mustang Tech 0
S Do I have to drop the fuel tank to install a battery tray in the trunk? SN95 4.6L Mustang Tech 14
joesgt281 Battery Relo to Trunk Help Please Classic Mustang Specific Tech 29
S Relocating Battery to Trunk w/Taylor Kit ?s SN95 4.6L Mustang Tech 2
B trunk mount batteries... I know search but still and lalalala Fox 5.0 Mustang Tech 9
LXSTASY Whose got a battery in the trunk? Fox 5.0 Mustang Tech 8
B Moving battery to trunk, worth it? 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 8
deadlast Battery kill switch after relocated to the trunk? Fox 5.0 Mustang Tech 2
N msd and battery box in the trunk need help Fox 5.0 Mustang Tech 1
P moved the battery to the trunk, making room for the turbo 1994 - 1995 Specific Tech 8
Dan95-5.0 relocated battery to the trunk....completed 1994 - 1995 Specific Tech 21
R trunk mount battery wiring questions Fox 5.0 Mustang Tech 1
Tim65GT Trunk Battery Power Distribution Panel Classic Mustang Specific Tech 0
NJCstang battery in trunk with 3g alt Fox 5.0 Mustang Tech 1
6 Battery in trunk questions Classic Mustang Specific Tech 13
mustangsally93 Battery trunk box Fox 5.0 Mustang Tech 0
04GT Trunk Mount Battery Kits SN95 4.6L Mustang Tech 3
hoamskilet relocating battery to much wire? 1994 - 1995 Specific Tech 12
Dan95-5.0 Relocating battery to trunk 1994 - 1995 Specific Tech 53
68rustang Battery in the trunk? Classic Mustang Specific Tech 11
Shakin66 Trunk mounted battery ideas.. Classic Mustang Specific Tech 18
chobracobra Battery in the trunk? Fox 5.0 Mustang Tech 11
S Trunk Battery Power Loss???? Fox 5.0 Mustang Tech 9
Similar threads