Master battery switch locations

[Michael C Henry]

I have a hard to get to master switch on the positive side.It's an effective theft deterent but it also causes me to leave it on when first turning the ignition off on what is was to be a short time . Next thing time has gone by ,the fans came on and the battery is dead. saw a 289 comp car at SAI and noticed they had located the master and starter switches on a tab below the dash at center over tunnel. Looked exteremely handy. I've seen master switches on rear bulkhead between the seats. Ive noticed the locations on the NASCAR cars on the dash.
My current location isn't accessable by the driver when belted in.You can emagine being all belted in and having to ask someone to turn the switch on and they can't find it.I under stand the master switches are supposed to be accessable from the outside in an emergency. I'm looking for suggestions, pictuers and Sources.What have you done or seen that is a great idea?What would have done better next time?

[Campy]

Michaeel C. HENRY
My switch is located in the trunk mounted in my battery box. I noticed I had ample room in the box, so it seemed like a good idea. So far it works just fine. What I don't understand is that you claim that your cooling fans come on which causes your battery to drain. My fans can run for a few hours on a good charge. I suspect your battery either needs replacing, the battery is low in H2O or your charging system is not sufficiently charging. Sometimes the short trips we take have the same effect. I purchased a trickle charger from my local auto parts store and keep it plugged in when the car is garaged. I always have a fully charged battery. I never use the cut-off switch.
You may also consider tying a scarf around your steering wheel to remind you to turn on the switch.

[Michael C Henry]

It is true I don't have a large atl.But my battery is a new Optima.I have four fans on two thermostatic swtches. They don't make a lot of noise and about fourty five minutes make the battery real tired.I tried a BatteryBrain. I had every combination go wrong including wrong selector position and at last the internal connections gave up completely.I once, while siiiting in street infront of a friends house, I got involved in a conversation with a local traffic cop.I'm sitting in my car,never heard the fans running.forty five minutes later ready to leave and nothing Battery low and couldn't even jump it Had to remove the batteryBrain to jump got it to relite .The contacts inside the BatteryBrain never reset , under any cercumstancesI abandoned that.No electrcity no electric fuel pumps. If I have a little battery and can get fuel to the carb just a slight role third gear let out he clutch and it will start. I want another Master Switch,probably on the Ground side to cut battery off emergency or not.Ive thought about in the dash ,under dash on the trans tunnel ,rear bulkhead between the seats.Some where that I can reach while belted in not in danger or a hazerd ,conviently located easily identified an accessed by driver or emergency personel.

[HighPlainsDrifter]

Racing bodys want to be able to turn of your car if something bad happens. Nhra requires a master cut off switch at the rear of the car,some put it between the license plate and tail light. You can also have one on your trans tunnel for for easy reach and then take off the switch knob at the rear of the car and use it only at the track or hotel overnight.
Perry.

[427sharpe]

I placed mine between the seats on the bulkhead. Easy to route the cable, easy to access and it meets all the rules of the various racing organizations about external access. NHRA requires a small lightning bolt decal on the body, just above the switch. I had the decal reproduced in aluminum and it is relatively unobtrusive. From this position, I can turn it while seated, or from either side of the car without hassle.

[Bob Parmenter]

Hi Michael,

Hope to see you again at Red Hook on the 16th.

You can put it just about anywhere you want, but you have surmised correctly to put it on the ground circuit. It is less sensitive to amperage draw and won't require as much concern for cable size.

Now the part that will likely get me flamed!
Part of your current problem is the Optima battery. I've had several hot rod friends use them. The idea of a jell filled battery that is less sensitive to vibration and mounting position is very compelling. However, they have had similar problems as you with low power after sitting for a while. The speculation is that the battery "doesn't like" the infrequent charging cycles of a hobby car that is infrequently used. There may be a more sophisticated analysis of the problem, but that seems to be the empirical evidence. Most of us have had better service from a dry cell alternative sold under the Odyssey brand (and perhaps other names). It has many of the same "advantages" as the Optima and is smaller. As a replacement in the above referenced hot rods, with no other changes to the charging system, they have performed very satisfactorily.

Hope this helps.

[Cobra20646]

Bob,

You said, "You can put it just about anywhere you want, but you have surmised correctly to put it on the ground circuit. It is less sensitive to amperage draw and won't require as much concern for cable size. "

I think your wrong with stating that it is less sensitive to amperage draw, unless you are placing the switch other than in line with the main ground lead from the battery.

I always thought that the switch was to totally disconnect the battery from the cars electrical circuits. In this regard, it would make no difference if the switch was placed in either the positive or negative lead of the battery. The only concern would be to have a switch rated to handle the starter motor current demands, which are very demanding.

OR..... maybe I'm wrong in my thinking here. Are the switches only killing the engine, in which case they only have to disconnect the ignition circuits? Still effective for safety and theft deterent.

- Jim -

MICHAEL,

THE FIRST QUESTION THAT I HAVE IS "WHY ARE YOUR FANS RUNNING FOR FORTY-FIVE MINUTES AFTER SHUT-DOWN???" YOU NEED TO CONSIDER AT WHAT TEMPERATURE YOUR FAN CONTROL THERMOSTATS ARE OPERATING. UNDER ABSOLUTE WORST CONDITIONS, IN AUGUST, MINE MIGHT RUN FOR THREE OR FOUR MINUTES AFTER SHUT-DOWN.

I AGREE WITH BOB P.-- THE OPTIMA BATTERIES ARE REALLY "QUIRKEY" (AN OBVIOUSLY TECHNICAL TERM). THEY ARE DESIGNED FOR "DEEP CYCLING" BUT NOT TOO DEEP . I USE A BANK OF THREE OPTIMAS TO POWER MY TRAILER. AFTER RE-CHARGING SOMETIMES I HAVE POWER AND SOMETIMES I DON'T. ON A SCALE OF 1 TO 10 MY SATISFACTION LEVEL WITH OPTIMA IS ABOUT A 6.0. (THAT'S ON A "GOOD" DAY - WHEN I HAVE POWER).

BOB ALSO MENTIONED THE ODDYSEY BATTERY. I HAVE ONE IN MY ERA COBRA. MY SATISFACTION LEVEL IS 10.0. THEY ARE JUST A LITTLE PRICEY BUT THEY ARE SMALLER AND BUILT LIKE A BRICK. IT SEEMS THE MORE YOU ABUSE THEM THE BETTER THEY LIKE IT.

NOW FOR BATTERY SWITCHES: THE PRIMARY PURPOSE OF A CUT-OUT SWITCH IS TO DISCONNECT "ALL" OF THE BATTERY POWER FROM THE SYSTEM AS A SAFETY CONSIDERATION - - INCLUDING IF NOT ESPECIALLY THE FUEL PUMP(S). FOR THIS REASON YOU WANT THE "SAFETY" CUT-OFF SWITCH LOCATED IN THE "HOT" LEAD OF THE BATTERY AS CLOSE TO THE BATTERY AS YOU CAN GET IT WHILE STILL KEEPING IT ACCESSIBLE TO THE DRIVER WHILE STRAPPED IN. IF YOU WANT A SWITCH FOR "SECURITY" PURPOSES YOU CAN INSTALL A SECOND ONE IN A HIDDEN LOCATION. THE SAFETY SWITCH SHOULD ALSO BE ACCESSIBLE TO THE PASSENGER AND TO RESCUE PERSONNELL. BY ALL MEANS IT SHOULD CUT-OFF THE FUEL PUMPS. IT'S ALSO A GOOD IDEA TO INSTALL AND "IMPACT SWITCH" IN THE POWER LEAD TO THE FUEL PUMP SO THAT IN THE EVENT OF A COLISION THAT MAY RENDER THE DRIVER UNCONCIOUS OR INCAPACITATED THE FUEL WILL NOT CONTINUE TO FLOW THROUGH A RUPTURED LINE. FIRE IS AN UGLY THING AND A GASOLINE FIRE IS THE PRINCE OF UGLY. THEREFORE A SECOND BATTERY TO OPERATE THE FUEL PUMP(S) IS NOT RECOMMENDED.

Y'ALL HAVE A REALLY GREAT DAY,

BLACKJACK

[Roscoe]

I have an Optima in the trunk with a large cutoff switch. I connected a rod to a "T" handle which runs through the rear wall into the cockpit. Shuts the whole thing down.
Roscoe

[Back in Black]

In the trunk...it would certainly slow down a car thief on the street, long enough for moi to arrive, upon the remote page from the alarm. The alarm must be on a seperate circuit of course.

The info on the batteries is good to hear. As soon as I get a chance, my turnkey will get an Oddessy battery.

[Michael C Henry]

The decal is a great idea > Who supplies that?My current master switch is on the positive side on firewall reach up under the dash and flip it .But I cant reach it after getting all belted in,What a PAIN.
Currently I'm planning on putting a Master cutoff switch on the trans tunnel where I can access it easily in full view but on Negative side of the circuit.That way A flash from a short wouldn't be a problem in the event of the trans or something else moving. Why would you get away with a smaller cable on negative side of a circuit ?What goes out has to get back in. The smallest cable any where in the circle would become the limiter.They call it a circuit.
Can you emagine all the switches a guy would have to set or check if every sanctioning body were obliged?

[SuperHart]

I placed my battery master switch in the trunk attached to the battery tray. Since I have carpeted trim panels on the sides of the trunk to hide the battery there is a small access hole in the panel to insert the red plastic "key". My switch kills ALL power from the battery EXCEPT the theft alarm. I switch off the battery, remove the "key", lock the trunk, and arm the alarm which has a perimeter sensor and voice warning. Then I can sit back and dare someone to try and mess with my cobra.

I admit that placing the shutoff in the trunk is somewhat inconvenient but it seemed much safer if I plan to leave the car unattended at any time.

[Okiesnake]

How is the cut-off switch on either the positive or negative side of the battery going to kill the motor if the motor is already running? The alternator will keep providing power and complete the circuit. You can completely disconnect and remove the battery once the motor is started and the motor will keep running. Granted you won't be able to re-start it.

[Bob Parmenter]

Michael,

You are correct, it is a circuit. There are some other considerations too. Assuming our discussion here revolves around a rear mounted battery, due to the design of our cars, the longer cable will be the power cable (+) as it goes, usually, to the starter/solenoid, the shorter is the ground (-) since it will go directly to the chassis (usually somewhere near the batt location). The chassis acts as part of the return "cable". Assuming good connections at each electrical consuming device to ground, the chassis offers very low resistence. Given the shorter distance from the battery gound terminal to the chassis, you can get by with less size cable. Larger is better, but not necessarily required. Second, the greater amperage draw is on the power side (e.g. starter). Some of the energy is used by the device to do it's job ( converted to work & heat), thus less energy going back.

Further thought on components working after the cutoff switch is opened; does your power cable have a smaller "pigtail" coming of the terminal ahead of the cutoff switch? If so, that would continue to supply juice even though the main cable is interupted. BTW a cutoff switch in the ground cable loop would open the circuit through the battery for that pigtail as well, disabling the device.

[HighPlainsDrifter]

Okiesnake;
What you need to do is take the output of the alternator [large red wire] and run it to the battery side of the master cut of switch,then when you turn it off, the engine will shut of instantly.
Perry.

[Okiesnake]

Thanks HighPlainsDrifter.

[niles]

Excellent comment on positive switches.
I was planning to put it on neg side; inorder to shut down a running motor.

Am I missing something? It would seem to me that if the neg side of the battery is not attached to ground, the current would have so place to flow?
thx
gn

[Michael C Henry]

You can break the circuit any place you desire.If you put it on the negative side and it is not bypassed for items like the alarm it is as absolute as the positive would be. The up side for the neg is if you inadvertantly short it nothing happens .No sparks or great arks. Then the positive side is supposed to be routed through switches before going on to the devices and evntually to ground and back to battery.

[cobrashoch]

I'm a bit confused here.(what's new?) I have been NHRA racing for years and have always put the exterior kill switch to the negitive side straight off the battery. On my cobra, the battery(s) are in the trunk and I have two switches that need both closed to make the car go. One is on the bulkhead between the seats and the other is below the trunk, middle and outside. Either switch will kill the engine because the MSD box is wired to the negitive via the switches.
Under no circumstance can I think of why I would wire the kill switches to the positive side. My logic is simple.
In a bad wreak, as I have seen ,(and expierenced) the postitive wires everywhere will still make ground and cause shorts. I.E.- fires. If you totally remove ground nothing works and nothing can short. I also have a tipover kill switch that will kill everything if the car gets 90 degrees or bottom side up. Again wired to the negitive side.
Anyone for the positive side argument? I may be missing something here. I have been wrong before on this stuff.

cobrashoch

[Michael C Henry]

I'm looking at Summit and Jeg's both nolonger offer the switches w/the removable red handles .What do you think happened?