QWKDTSN Posted March 29, 2001 Share Posted March 29, 2001 Hey guys. I'd like to install a battery shut-off switch sometime on my Z. It's been reccommended several times to me recently and just seems like cheap insurance. I'd like to be able to shut off the battery without having to pop the hood. It seems like I'm always connecting and disconnecting the positive terminal while working on the car. What I was thinking was this: would I be able to mount a shut-off switch to the inner fender near the battery and be able to access it by sticking my hand in through the wheelwell? I know I'd have to drill a hole. I guess my question is, is this logical, or should I just install one on the interior (longer wires) or one of the terminal-mounted ones (having to pop the hood)? I know a guy with a battery switch on a Buick drag car that's mounted near the taillights (battery in the trunk). This just seems sort of pointless to me, because it's a streetable car. He drives it everywhere. If someone wants to steal it, the battery switch is very noticable. Having it hidden up inside the fenderwell near the battery makes sense to me. What do you guys think? Quote Link to comment Share on other sites More sharing options...
pparaska Posted March 29, 2001 Share Posted March 29, 2001 I relocated my battery to the package self, just behind the passenger seat. I ran the positive cable from the sealed battery box, through a cover plate for teh tool box opening on that side, to a battery cut-off switch mounted down in the tool box. Then the cable comes out of the forward bulkhead of the tool box. The switch is mounted on this forward bulkhead. The switch is a real pain to get at, so it's a bit of a security measure having it like this. I just reach behind the passenger seat and can turn it on/off and take the removeable key with me. Not to worry, I have other safegaurds if someone gets around the switch that are very well hidden. Only my wife and father know where those are . I know you want to keep from having to pop the hood, but here's an idea. For a battery in th stock location, how about this: Mount a battery cut off switch in the firewall, down in the high foot well area on the passenger side, but out of the way of where someone could hit it with their foot. Have the handle in the interior and the terminals of the switch would be on the firewall in the engine compartment. That way you could run a short cable from the battery down to the switch, then from the switch to the starter. There would be no to tiny increase in cable length this way. I think you fender well idea would be good as well. JMO, ------------------ Pete Paraska - 73 540Z - Marathon Z Project pparaska@home.com Pete's V8 Datsun 240Z Pages Quote Link to comment Share on other sites More sharing options...
Owen Posted March 29, 2001 Share Posted March 29, 2001 If it's a drag car, your friend probably has it for safety reasons at the track. Either that or he thinks it's cool. Owen ------------------ http://www.homestead.com/s30z/index.html Quote Link to comment Share on other sites More sharing options...
QWKDTSN Posted March 29, 2001 Author Share Posted March 29, 2001 Hmm, thanks for the suggestions Pete. I'm trying to stay as stock on the car as I can right now (stock interior minus seats, stock battery location, stock fuel tank, etc) because the car I bought was so clean in that regard I can't bring myself to chop it up. That's also why I can't bring myself to drop in a V8 yet I'll take a look at the firewall inside the car and underhood and see if I can find a good location for a switch. The only problem with mounting it in the wheelwell is that my car is going to be LOW when my struts are done and there's not going to be much room room to reach in above the tire Quote Link to comment Share on other sites More sharing options...
DavyZ Posted March 29, 2001 Share Posted March 29, 2001 Nion, I have seen cutoff/kill switches built in to the cigarette lighter element! It looks ordinary and "stock" but does its job! Recently a friend of mine had his Toyota Corolla twin cam (rwd) stolen. He just picked another one up and made a kill switch from one of the many electrical buttons on the console. Using pre-existing buttons, switches, or even the cigarette lighter idea keeps our interiors and exteriors intact and less conspicuous. Hope this helps. Quote Link to comment Share on other sites More sharing options...
Andrew Bayley Posted March 29, 2001 Share Posted March 29, 2001 Interesting question. I've been thinking of moving the battery to the back myself, but I don't like the idea of a mandatory cut off switch at the drag strip. The following is from the 2000 NHRA rule book: From General Regulations 8:4 MASTER CUTOFF Mandatory when battery is relocated. An electrical power cutoff switch (only one) must be installed on the rearmost part of each vehicle and be easily accessible from the outside of 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 the switch is "push/pull" type, "push" must be the action for shutting off the electrical system, "pull" to turn it on (huh huh, pull to turn it on ). Any rods or cables used to activate the switches prohibited. Switches must be located behind rear wheels on rear engine dragsters. Quote Link to comment Share on other sites More sharing options...
pparaska Posted March 29, 2001 Share Posted March 29, 2001 Yeah, I've had long discussions with the guy at M.A.D. Enterprises about that assinie rule. I understand the need for the safety crew to be able to kill battery power to the car. But what's really stupid is the rule says it must be on the POSITIVE side cable. That's the stupid part. Usually the switch is situated in the back of the car where if it got punched in, the terminals on the switch might find themselves grounded out on some nearby sheet metal - instant high current short, and a high possibility of a fire or exploding battery or acid spewing. The guy at M.A.D. Enterprises (can't recal his name, but M.A.D. are his initials) thinks it would better to put the cut-out switch on the ground cable. I agree, it carries just the same current as the positive one, and is just as effective to cutting power if interrupted (assuming ALL circuits are fed through this cable and none before). So if you cut the ground side of the circuit, it's just as good. (Ignoring the alternator powering the ignition, which you need to handle with a special switch or relay anyway.) The benefit is that if the car gets in an accident and the switch terminals hit sheet metal, you have no positive to ground short, just a ground to ground short, which in the worst case means that the switch will then be ineffective. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted March 29, 2001 Share Posted March 29, 2001 While we're on the Battery subject, has anyone else entertained the Idea of putting one of those Optima batteries in one of those tool boxes behind the seats? I was kinda eyeballing it, although I ended up with a large amp Interstate battery under the hood still. Just an idea to kick around. Lone Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted March 30, 2001 Share Posted March 30, 2001 I'm with Pete - somewhat. Putting it on the hot side seems weird to me. If it gets punched in it will certainly short on something and if it wasn't a bad accident before the hot wire grounding will make it serious! However, if it's in the back and gets punched while it's on the ground wire it'll still be bad - it'll short to ground and the switch will be ineffective. If it has to be used it won't work. My thought had been to mount it ON the battery box and run a rod out the back for a push OFF type lever. However the rules quoted seem to say that rods aren't allowed! IMO the shorter th ewire run before the switch the better and if the switch can be placed in the driver's reach then it should be! My sealed box is mounted just in back of the tool boxes in the center of the car over the rear axle. I did this for handling mostly as putting it in the rear corner seemed wrong. I also couldn't fit my box securely there with my fuel cell where it's at. I've been looking very hard at the various switches, most especially the Flaming River one, but now that you mention it I seem to recall that MAD had some good ideas too. I'll have to hunt their site up and see what looks good. Oh - I too considered sinking a box into the tool well. RX7 folks do this often with teeny tiny batteries (can provide URLs). However cranking power might not be what we'd want on a cold evening or heatsoaked motor I've not yet bought a battery, a switch, or wired my box up. Suggestions needed here too... Quote Link to comment Share on other sites More sharing options...
Guest RON JONES Posted March 30, 2001 Share Posted March 30, 2001 Most Race Cars that have trunk mounted Batterys also (not street cars that race at the track)run one wire Alternators that just run a lead to the positive side of the battery.The main reason for this switch is to shut the motor off.If the shut off switch is conected to the Negative side,when you shut that switch off,Your Car will still be running.On My first visit to the race track with My old Malibu,They made Me start the Car at Tech and They made sure the Car shut down when that switch was shut off.I didn't Have a one wire ALT. in that Car,but I did Have a relay hooked up so the Car did shut Down.The reason For the switch to be at the back of the Car is for Them(NHRA) to easly get to it.I know a few Guys that have two switchs,One on the back of the car,and one near the Driver. [This message has been edited by RON JONES (edited March 29, 2001).] Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted March 31, 2001 Share Posted March 31, 2001 Thanks Ron, I wondered about the car not shutting off. The MAD folks sell a relay setup for just that purpose. IMO it's a pretty good idea for th etrack to test it the way they did - very smart and better than sticking you with the "rules" that might not be best. I've not yet got an alternator and am waffling on that too. One wire just sounds so easy! It's not like I'll have an idiot light anywhere much as I migh tlike one. Quote Link to comment Share on other sites More sharing options...
DavyZ Posted March 31, 2001 Share Posted March 31, 2001 Regarding the Optima battery--oh yea, that's the one for me. I have had it with leaking batteries etc, on some of my past cars (and the 260Z--rust, rust, rust) and will fork out the $$$ for an Optima. I have not done the cutting, but I will sink it in the center (or right side) where there's room back there. I took a look at Mike Knell's set up on the "mule" and the sunk battery in the back looks really good. I was shocked at the apparent room underneath for a relatively large item like a battery. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted March 31, 2001 Share Posted March 31, 2001 Cool, you got to see the much read about mule huh? Thats pretty cool. There are alot of things that are not crystal clear in the JTR manual, but I'll tell you, overall, its really well written and the swap pretty well engineered. Mike Knell/JTR really did a good job with it. Lone Quote Link to comment Share on other sites More sharing options...
DavyZ Posted April 1, 2001 Share Posted April 1, 2001 The mule was my first V8 converted Z ride...I nearly wet my pants from the experience. This was when Mike Knell put out his first edition of the manual (I still have it too!) and he let me drive the car--I didn't make it past 3rd gear--he thought it was pretty funny! Now, many moons later, I am building my own V8Z. I caught the bug and it has never gone away. I really want to finish my car and drive the sucker! David Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted June 8, 2001 Share Posted June 8, 2001 This question of where to put the switch has really been bugging me. I'm in the midst of wiring mine and about 10minutes after picking up the last bit of wire I need to run in order to hook the switch to my HOT side I finally realized why using the negative is better. Duh, I'm an idiot, doubly so since I just bought cable I migth not need! Switch on back of car - good idea. Can be reached by workers in an accident, meets SCCA, NHRAIHRA regs, yadda yadda. However, every foot of "live" hot wire is an accident waiting to happen. IF it ever grounds anywhere it will weld itself and begin sucking amps as it heats to amazing temps - unless the battery explodes first! So, switch on HOT side is bad! It increases the footage of HOT wire. In an accident, worst case, the switch is going to get trashed! If it's on the negative side it will simply ground and become ineffective, if it's on the hot side it will simply end up being a ground and the switch won't work. Still might be a fire but the chances are no worse really than if the switch wasn't there to begin with. Ya', not supposed to pass tech but most tech will consist, maybe, of hitting the switch and seeing if the car dies or not. I must be thick as when we had the conversation above this didn't click. Now I have 10feet of #0 wire to complete this wiring job that I might not need. When you plumb the switch to the ground side you can simply run a jumper right to the body of the car and not all the way to the front of the car (sigh). I think I'll measure and see if I can use this wire as my hot side and then use the old stuff as a ground. It's not as thick but for a ground I don't think that will matter. Run it to a few places off the switch in one run, strip of some insulation in a few spots, ground wherever I want along the run. Heck double it up if I need more amperage handling. If I do it with two pieces in parallel to the switch I can even get a pair of heavy duty breakers in case the car is in an accident and a really heavy load gets pulled from the unswitched run. Make any sense? Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted June 8, 2001 Share Posted June 8, 2001 I remember reading it somewhere, but can't recall where, but they used like a threaded rod ran through the back panel of the car that connected to the cut-off switch? They screw the rod on for the event and pin it or lock nut it, and then remove it for street driving, the only thing left is a small hole for the rod which could have a plug put in it. Not sure of the legalities for NHRA or whatever, but I think it was rather a clever idea. Regards, Lone Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted June 8, 2001 Share Posted June 8, 2001 That's an NHRA rule - if you use a rod it must be "push off" for th esafety crews. However to do this and still make it accessible to the driver easily I'd have had to mount it TO the batteyr box which is right between the tool doors. The problem there IMO is that I end up with one LONG rod into the car that sort of distrupts any storage room I've got. Strut bar back there is bad enough! I'm going with two switches. One will be mounted in back off of the ground circuit. The other will be on the hot side within reach of the driver, in the tool tray ala Pete's idea, and will reduce the length of HOT wire run in the car. Where this is sort of difficult is in the realm of trying to sneak a circuit or two out of the switches for an alarm and radio! If I use fuses on both leads then hitting the switch in back while the motor is running will put all of the juice through the fuse and likely pop it. In the case of the car sitting with the alarm on the fuse shouldn't blow and flipping the switch won't disable it. An option would be to run dedicated wires to the alarm and maybe the radio to maintain my stations (shrug). Still thinking this through but I believe it'll be safer unless someone can poke holes in it. Second switch is on the way, these puppies aren't cheap when you buy them in amperage ratings high enough to actually support things properly! Waa! Quote Link to comment Share on other sites More sharing options...
pparaska Posted June 8, 2001 Share Posted June 8, 2001 Jim, I ran a dedicated 10 gage wire from the always-hot side of my cut off switch to the radio area. I connected it to the always-hot terminal on the switch using a 12 gage fusible link (always use a fusible link at least 4 numbers larger than the wire size). Quote Link to comment Share on other sites More sharing options...
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