Trunk mount battery - Definitive thread on safety/legality

[dipren443]

So after doing some searching on here, I have yet to paint a super clear picture of what is and what isn't appropriate when moving a battery out back.

I would like to be able to do this once and do it right. I am certain that once my car is complete, I will definitely sign up for some HPDE's, a little autocross, open track days, etc...

So I am tapping into the collective knowledge of Pro touring.

So here are the questions...

For starters, when running an Optima, is a battery box required? Is a firewall needed between the passenger compartment and trunk?

How about external kill switches? Are they required?

I most likely will run MAD Electricals remote solenoid. From there, I don't know. Want to stick the battery right underneath the package tray, offset to the right/passenger side.

Any help and info, feel free to add it.

[Jim Nilsen]

With the cost of the Braille batteries vs Optima and the weight difference vs performance, I would seriously consider losing a litle weight and size and get the Braille. So far everyone that has one they bought from the HotRod Shop where I got mine has really been happy.

Hooking in a kill switch is always a thing to consider when doing all of this.

The choices are up to you as there are lots of ways to do it. But the battery is needed no matter what so you might as well spend $30 more if that and get the best and more.

Either the Braille or the Optima can be mounted in any position and in most all places without a battery box.

[dipren443]

With the cost of the Braille batteries vs Optima and the weight difference vs performance, I would seriously consider losing a litle weight and size and get the Braille. So far everyone that has one they bought from the HotRod Shop where I got mine has really been happy.

Hooking in a kill switch is always a thing to consider when doing all of this.

The choices are up to you as there are lots of ways to do it. But the battery is needed no matter what so you might as well spend $30 more if that and get the best and more.

Either the Braille or the Optima can be mounted in any position and in most all places without a battery box.

Dammit man... Why did you have to bring up Braille... I have contemplated switching to a Braille battery for a while. I already have a yellow top Optima, but may make the switch. That yellow top is a boat anchor. Which size Braille would you recommend?

[CarlC]

For me adding the switch was a no-brainer. It allows disabling of system power for servicing the car, acts as a theft deterrent, and is a major safety item allowing shutdown in case of electrical problems. It can be mounted inside of the trunk for stealth with a removable plunger that is external to the body.

For HPDE the battery needs to be securely mounted. I use a bracket from Speedway that works just fine and there has never been a problem from the host organizations. No other firewall besides what the factory offered was needed. There may be additional NHRA regulations that you may want to consider if you fall into the requisite category(s).

The Camaro has a small auxiliary power panel in the trunk. It has a 3A bypass for the ECM and various memories to stay intact, a breaker for the fuel pump, and another for the amplifier. Since it only ties into the battery bracket there are no additional holes drilled in the body. I'm working on an external handle/plunger that will route through a bumper bracket bolt hole that will allow turning the switch off with the trunk closed (NHRA).

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[Motown 454]

Thats a nice setup Carl . What size (Amp)switch did you use ?

[CarlC]

It's just the standard trunk mounted on/off switch offered through various distributors. My friend John gave it to me since he thought it was bad, but it was fine. Free is good!

[NOT A TA]

Does that turn the engine off Carl or just the battery? I've had trunk mounts before with a battery shutoff external mount but tech requires engine shutoff to be correct. I want to move the battery in my Firebird and want it correct this time.

[Jim Nilsen]

Dammit man... Why did you have to bring up Braille... I have contemplated switching to a Braille battery for a while. I already have a yellow top Optima, but may make the switch. That yellow top is a boat anchor. Which size Braille would you recommend?


I have the B3121 which fit in place of my Odessey. It weighs 21 lb. and is 6.8 x 5.8 or so and has terminals that can mount top and side. For $190 tax included it has it's advantages.

Really think this out before you do it. Flaming River makes a kill switch that is a push to kill instead of turn and can be set up in a lot of creative ways to enhance the theft and saftey of the car.

[Burnout1121]

Im in the same boat. I have a shutoff switch I got for free that has 2 posts, kind of like this http://www.summitracing.com/parts/TAY-1032

Im pretty sure that the car will still run if I only wire it to the battery. Can I run the alternator wire to the trunk and back so I can run it in with the battery? Or would that blow something up...I'm not very good with wiring.

[dipren443]

I have the B3121 which fit in place of my Odessey. It weighs 21 lb. and is 6.8 x 5.8 or so and has terminals that can mount top and side. For $190 tax included it has it's advantages.

Really think this out before you do it. Flaming Riover makes akill switch that is a push to kill instead of turn and can be set up in a lot of creative ways to enhance the theft and saftey of the car.

Jim,

I have all winter to do this. That is precisely why I posted this, I most definitely want to do this right. I HATE doing things twice.

This the one you are talking about?

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[CarlC]

It only kills power to the battery. However, since the fuel pump power is wired directly from the main switch, and if the 3A bypass is disabled, turning off the main switch will also turn off the power to the fuel pump.

[Jim Nilsen]

Jim,

I have all winter to do this. That is precisely why I posted this, I most definitely want to do this right. I HATE doing things twice.

This the one you are talking about?

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Yes it is.

[Jim Nilsen]

Im in the same boat. I have a shutoff switch I got for free that has 2 posts, kind of like this http://www.summitracing.com/parts/TAY-1032

Im pretty sure that the car will still run if I only wire it to the battery. Can I run the alternator wire to the trunk and back so I can run it in with the battery? Or would that blow something up...I'm not very good with wiring.

If you run the wire from your alernator to your battery instead of to your starter and put the kill switch between the positive cable and the rest of the car, the alternator cannot give power to the car once the switch is turned off.

The Flaming River kill switch has terminals that will kill the power to the field on the alternator if needed.

I have a one wire alternator and this setup works good to kill the car.

There are so many ways to wire this kind of system up and the biggest hurdle is the wiring harness you may already have and how to make it work as a system without running another mile of wire to do it.

[MonzaRacer]

i used a painless master switch, and used it to cut the battery ground,,,, killed car instantly.
I simply had my 8ga alt wire ran to solenoid on fierwall,made my own starter jumper and ran a 2/0 from solenoid to starter I had double insulated 2/0 from hatch mounted battery to solenoid and also used piece of heater hose and some split loom and a hole grommet for battery positive cable through firewall to solenoid.
if you cut all grounds (except memory items) car will die.
My ground was 2/0 from batt neg to switch , then switch to clean chassis ground. also added several ground from block to chassis(unibody as it was a 77 Monza) if you interrupt positive,the alt can still make circuit to ign,killing negative and no complete circuit.

[Jim Nilsen]

i used a painless master switch, and used it to cut the battery ground,,,, killed car instantly.
I simply had my 8ga alt wire ran to solenoid on fierwall,made my own starter jumper and ran a 2/0 from solenoid to starter I had double insulated 2/0 from hatch mounted battery to solenoid and also used piece of heater hose and some split loom and a hole grommet for battery positive cable through firewall to solenoid.
if you cut all grounds (except memory items) car will die.
My ground was 2/0 from batt neg to switch , then switch to clean chassis ground. also added several ground from block to chassis(unibody as it was a 77 Monza) if you interrupt positive,the alt can still make circuit to ign,killing negative and no complete circuit.

Some tech rules do not allow the ground to be used to break the circuit because in an accident torn wiring can make the ground in their eyes. I have never believed it would ever make a sufficient ground but I didn't write the rules and MAD enterprises has fought with the NHRA over it a long time ago. It really does work and is a lot easier to wire that way but the reason for the fancy solenoid from MAD was to make it all work according to the rules.

The Flaming River switch if installed in the rear of the car might actually kill everything in a rear impact as it is a push button and not a rotating switch.

[amargari]

Jim is correct. You can not use a negative disconnect to shut down the car. I used the heavy duty summit switch. I wish I had purchased a switch with dual terminals that would shut down the main power as well as the alternator.

[67 455 Bird ragtop]

Double check your specific tech specs on cutgoff switches. I'm pretty sure some, NHRA, require a PUSH type kill switch only to be used and must also kill the motor.

[amargari]

The following are from the 2008 NHRA Rulebook:


8:1 BATTERIES

All batteries must be securely mounted. Must be of sufficient
capacity to start vehicle at any time. Batteries may not be relocated
into the driver or passenger compartments. Rear firewall of .024-
inch steel or .032-inch aluminum (including package tray) required
when battery is relocated in trunk. In lieu of rear firewall, battery
may be located in a sealed .024-inch-steel, .032-inch-aluminum, or
NHRA-accepted poly box. If sealed box is used in lieu of rear
firewall, box may not be used to secure battery and must be
vented outside of body. Relocated battery(s) must be fastened to
frame or frame structure with a minimum of two 3/8-inch-diameter
bolts. (“J” hooks prohibited or must have open end welded shut.)
OEM-located batteries without complete OEM hold-down hardware
must be secured to OEM battery box/tray using the same 3/8-inchdiameter-
bolt hold-down method described in previous sentence.
Metal battery hold-down straps mandatory. Strapping tape
prohibited


8:4 MASTER CUTOFF
Mandatory when battery is relocated or on any vehicle running
9.99 or quicker. An electrical power cutoff switch (one only) must
be installed on the rearmost part of each vehicle and be easily
accessible from outside the car body. This cutoff switch must be
connected to the positive side of the electrical system and must
stop all electrical functions, including magneto ignition. The off
position must be clearly indicated with the word “OFF.” If switch is
“push/pull” type, “push” must be the action for shutting off the
electrical system, “pull” to turn it on. Any rods or cables used to
activate the switch must be minimum 1/8-inch diameter. Plastic or
keyed switches prohibited

Hope this helps

[WS6]

does SCCA require a positive side kill switch or will one on the ground be acceptible?

I didn't even think to include a kill switch with my design. I did however not keep the 2/0 starter feed live 100% of the time. I have a 6ga wire off the alt for that but it has a circuit breaker on it for safety.

[67 455 Bird ragtop]

What I plan to do with my cut off switch is to have two different tail light housings. One for street and one for the track. The track one will have a hole in it for the cut off switch rod to pass through. This way it's legal for the track but no one will be able to disable my car when driving it on the street. Just my .02.

[rb70383]

Can anyone get a wiring diagram for the new chargers? Their battery is in the trunk from the factory. I'm curious as to the factory's approach to doing this.

[amargari]

The Charger's wiring most likely isn't that special. If you are not looking to be NHRA legal then you do not have to mount a rear cut off switch. That is the added complexity for this swap. If you didn't need the switch, you would just run a ground wire and a large 1/0 gauge wire to the starter and be done with it.

[WS6]

The Charger's wiring most likely isn't that special. If you are not looking to be NHRA legal then you do not have to mount a rear cut off switch. That is the added complexity for this swap. If you didn't need the switch, you would just run a ground wire and a large 1/0 gauge wire to the starter and be done with it.

Which leaves a nice wire with power on it constantly that will do amazing damage if it ever contacts ground. Whether you're trying to pass tech or not, always do a remote relay setup like MAD electronics sells so that the starter wire isn't powered the whole time it's running the length of the car. It's a safety issue even on the street. JMHO

[rb70383]

See I was just reading about Mad's trunk battery kit with the solenoid. That is exactly how I am going. I am wondering if the factory is going the same or leaving a live wire the whole chassis. If so any extra protection for it? I am completely rewiring the Challenger from scratch. It will have ignition switched relays to power sections of the fuse block. More like the modern cars of today. I am also going to eliminated the fuse panel under the dash and incorporate it into a PDC under the hood. Sorry for the minor thread hijack

[amargari]

Trey,
I hear you. That's how I set mine up. I was just commenting on the stock new cars system. They can get away with it because I am sure they engineered the car to have a trunk mount battery. They then crash tested the car with the battery and wiring.

[H2Ogbodies]

Another thing to remember is if you have a fuel cell, the car has to have a fire barrier seperating the cabin area from the trunk. When I did my last system, I had main charge lead from the alt. (4 gauge) running to the shut-off along with the positive cable from the trunk. Then, I ran a 6 gauge wire to a 150 amp circuit breaker which then ran to a master power junction. from there, I tied in all my IGN. on +12V leads. Of course it all went through a fuse/relay center but you get the idea. I added an extra 1-gauge positive cable to the front so I could build a remote positive/negative jumper terminal lugs in case I ever needed them. I build my own wiring schematics but I use a lot of Taylor parts....all stuff is USA made so I support them. MAD is good stuff too though-i've talked with Mark a lot on charging theories in the past. Construction equipment is all broke on the negative side so yes, it works just as good...I think the NHRA just sees a once in a million shot of something happening...lol.

[Jack67]

This is an informative thread, thank you.
What is the best path to snake thru from trunk to starter?
Anyone ever use the rocker box?
Thanks in advance
JP

[LowBuckX]

I just finished my trunk and trunk mount battery set up .I used a Moroso sealed battery box (yes steve finally) 2 gauge from bat to ford solenoid then to starter. main feed is 6 gauge from batt to Battery brain (see pic) to 140 Amp breaker to junction on firwall. Box is sealed and vented to outside. Im getting 14.07 volts charging at the battery. Ground is 2 ga all the way to starter then ground straps from body to motor and body to batt in rear.

The battery brain is a bad a$$ feature. I found a cool as hell place to have the disconnect button. I gutted my cig lighter and put the button in the bottom of socket then inserted lighter back into hole. now I can push the cig lighter in to connet or disconnect the batt...

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[1969CamaroRS]

Anyone know if for the Mad Electrical Remote starter solenoid does it matter the mounting orientation? As in can you mount that thing any which way (upside down or sideways)?

Thanks,