battery disconnect switch

[Sho Amo]

In able to run at my local track, im going to need a battery disconnect switch since my battery is in the trunk. From what ive heard im going to need a switch that is visible from the outside of the car.

what i want to know is has anyone done this to a daily driver car and made it somewhat hidden and accessible? I was thinking about running it behind the license plate but i feel like it would stick the plate out too much.

ive been looking at these types.
http://store.summitracing.com/partd...925143+4294859645+4294859644+115&autoview=sku


This is my current battery setup

 

[SHOZ123]

I believe you will also have to feed the alternator field wire off of this switch too. This is to make sure the engine dies when the switch is turned off.

 

[dodgebusta]

Saw this done with another type of car don't see a reason why it wouldn't work for a sho. Get a second tail light assy, and mount the disconnect switch in it. Have pigtails comming out of the light assy so you can connect one end to the battery and the other end to the wire you take off of the battery. Also by the looks of it you need a battery box. Just got get a marine black battery box and you should be fine there also.

Just remember to use a large enough cable 0/0 or 2/0 should do.

 

[SHOZ123]

Might need a metal battery box though. I use #2 wire in my '97 for the last 5 years. 0/0 or 2/0 is way too big really and just needless weight.

 

[dodgebusta]

Might need a metal battery box though. I use #2 wire in my '97 for the last 5 years. 0/0 or 2/0 is way too big really and just needless weight.

NHRA says you must have a battery box, does not specify metal or plastic. Just have to have a secured battery box. And gauge is personal opinion, if you go larger you can't be wrong, if you go smaller you can have at the very least melted wires, at the worst no more car. For the price difference, I would go larger cable, weigh on the side of safety.

 

[Sho Amo]

i was hearing about that too. ive got a new battery now its an advanced auto brand battery. im not sure wether it has to be sealed or not but i really should do that just in case.

Darn safety. i also have to buy a fire suit and blow down tube since im running nitrous now.

 

[SHOZ123]

Just saying about the box as I went to a track that would not allow plastic boxes.

As far as the wiring goes it is may be personal preference but certain electrical standards are pretty well thought out and serve their purpose.

 

[Sho Amo]

well i hope i dont need a metal box. the plastics are only $9
This just made me happy.
http://store.summitracing.com/partd...&N=700+4294925143+4294862977+115&autoview=sku

 

[dodgebusta]

Just saying about the box as I went to a track that would not allow plastic boxes.

As far as the wiring goes it is may be personal preference but certain electrical standards are pretty well thought out and serve their purpose.

WOW, I've done quite a few tracks that just want you to follow NHRA rules, although i think you do need metal if you run alcohol or nitrous, don't quote me on that. Also every track will be different and they are allow to make their own rules, so anything is possible

Also just found this in my ul standards elec book (since i'm at work right now) Here goes:
2ga is rated for 300amps, max of 400amps.
0/0 is rated at 700 amps, max of 800 amps.
0/2 is rated at 1000 amps, and max of 1100 amps.
0/4 is rated at 1200 amps, and a max of 1400 amps.

So just going off of that is what I would base my wire decision off of.

 

[Sho Amo]

good info.

 

[Mr Anonymous]

New England Dragway has the same requirement (which anyone attending the convention and planning on running at Street Night on Wednesday should be prepared for if you have a re-located battery).

I think that you could sink some kind of recessed box in the panel behind the license plate with the switch that would allow you to conceal it with the plate.

I agree with Paul that to make this work properly, interrupting the alternator field power should be part of the design. I am willing to bet however that most tracks don't actually test the functionality of the switch...

 

[dodgebusta]

I am willing to bet however that most tracks don't actually test the functionality of the switch...

Actually I have only every seen somebody tested once. And it WORKED~!

Agreed for the Alt, um have seen guys do a fuel cut out off of this too, really popular way of shutting the car completely down also keeps the fuel away from the engine incase of fire.

Heard once that BIR was going to make a rule to have a master battery disconnect and a fuel disconnect switch on anything that was pulling 12sec's or less.

 

[St Louis SHO]

You are correct! That's the grey area... It doesnt even have to be hooked up. :wave: Gateway Int'l only checks to see if it's there.

 

[SHO92]

Maybe tracks have gotten more strict over the years, but I've never had a switch on my cars, which both have had the battery in a plastic box in the trunk. I haven't been to the track in several years now but they only required the switch if you were racing. If you were just there for test and tune, they just checked to make sure the battery was secured.

What do they do about BMWs that all have the battery in the trunk or under the rear seat from the factory? The Lincoln LS has the battery in the trunk too.

 

[sho_ted]

if they follow NHRA tech rules it most be in an NHRA approved box or there must be firewall betwwen trunk and passenger area.

 

[gmorrell]

Unless the tech inspector is actually going to trace wiring to verify a battery lead disconnect, here's a suggestion:

Don't disconnect either of the battery leads. Unless you're very careful, this can create a load dump situation where the collapsing alternator field puts an 80V spike into the vehicle electrical system.

Instead, consider interrupting power to the fuel pump and the switched ignition +12V to the ignition coil pack and the engine actuators. When these circuits are opened, the engine will stop right now, and you won't created any load dump transients.

 

[SHOspazz92]

My local race track does not even have a tech inspection. I could race with 3 dead hookers in the trunk and no one would know.

-Sam

 

[Eric VerValin]

WOW, I've done quite a few tracks that just want you to follow NHRA rules, although i think you do need metal if you run alcohol or nitrous, don't quote me on that. Also every track will be different and they are allow to make their own rules, so anything is possible

Also just found this in my ul standards elec book (since i'm at work right now) Here goes:
2ga is rated for 300amps, max of 400amps.
0/0 is rated at 700 amps, max of 800 amps.
0/2 is rated at 1000 amps, and max of 1100 amps.
0/4 is rated at 1200 amps, and a max of 1400 amps.

So just going off of that is what I would base my wire decision off of.

What is the name of the "type" of wire used in battery cables? I was trying to do some math on that the other day. Does it have a name on it anywhere? THHX, THHN. ?
All the ones I've ever gotten were blank, which makes me think Advance sells Chinese wire.

 

[dodgebusta]

What is the name of the "type" of wire used in battery cables? I was trying to do some math on that the other day. Does it have a name on it anywhere? THHX, THHN. ?
All the ones I've ever gotten were blank, which makes me think Advance sells Chinese wire.

I pulled that directly out of a UL Electrical Standards book, that we have at work. I don't recall seeing a wire type. But I would assume the standard copper. But I also forgot to note that if you go with a "welding cable" style, i don't feel those figures would work, because they are a higher quality wire with larger amounts of insulation around them.

But like I said i pulled it out of a UL standards book, I assume they figure it out for minimum cable standards. So some cable of the same gauge may have higher ratings than this, but to be UL listed these are the standards.

 

[Eric VerValin]

THHN is an alphabetism or initialism which stands for "Thermoplastic High Heat-resistant Nylon-coated." THHN is a designation for a specific insulation material, temperature rating, and condition of use (suitable for dry and damp locations) for electrical wire and cable

THWN is an alphabetism or initialism which stands for "Thermoplastic High Water-resistant Nylon-coated."

Well, here is where I started... most commercial applications that I have done, are THHN. Now when I've had to wire up some large air handlers, its often damp inside, so they use THWN. The second is a LOT more expensive, the strands are smaller, and the coating is a lot more "rubbery". Thats the stuff I used when I wired up my fog's to a new relay.


I've always noticed a fine strand on automotive cables, but I also know it will need to be an oil resistant, heat resistant, also something that wont dry out after time. Just some "regular" wire isn't good enough. I was kind of trying to see if I could find a large bulk roll of it thru my supply house, and make my money back selling some cheap (nice) cable to others.

But the guys at the desk will look at me funny if I say "primary wire" lol ? Its just a term electrician's never use, unless we're wiring up a transformer..



Edit: I just remembered something else.... there may not be a designation for it, because there is 0 electrical code enforcement on vehicles, with the exception of government service vehicles (ambulance, fire, police), and Recreational Vehicles.

I work with the NFPA, and remember reading that a while back. And have not seen any updates to it yet. I guess they just lay the liability on the automakers, not the wire manufactures.