© Christian Arriero001-remote-batter-disconnect-kill-switch-install-painless-power-cutoff-optima
Painless Performance's battery disconnect switch is an easy way to protect your hot rod from battery drains and even theft.
With our hot rods, gasoline gets all the glory, but t hey also need electricity to run, and as we add more and more bells, whistles, gadgets, and accessories to the mix the electrical side of the equation becomes even more critical. In some cases these electrical items consume a little power even when the ignition is off. Now, if you drive your car or truck daily, that's not an issue; but if it sits between events, you might have a surprise next time you try to go for a drive: a dead battery. Installing a battery disconnect switch to kill the car's power is an easy solution to the battery draining while the ignition is off. The good news is that it's a pretty easy project to knock out.
© Christian Arriero Like with everything, there are choices to make. If you want the disconnect switch to be near you, for use in an emergency, then you could opt for something like this remote disconnect with emergency switch (PN 30205) from Painless. The kit comes with a 250-amp solenoid, push button, and hardware. It's not NHRA approved, but it's a good safety item if you track your car. Keep in mind this isn't a good option for storing your car since the solenoid draws 2.5 amps when engaged, so if left engaged it will drain your battery over time. Doing some research will keep you from wasting cash on the wrong type of master disconnect switch.
© Christian Arriero If you want to use the disconnect as hidden kill switch that can also isolate the battery for storage, then Painless offers a remote disconnect with a latching solenoid (PN 30206). With this type of solenoid there is no risk of accidentally draining your battery, so it's great for everyday use. The kit uses a 100-amp continuous-duty solenoid that is activated by an easy-to-hide switch. The solenoid is weatherproof so it can be mounted anywhere.
© Christian Arriero The simplest to install and least expensive option is this master disconnect switch from Painless (PN 50710). It has a continuous rating of 175 amps and a surge rating of 1,000 amps and is sold with and without the mounting plate. These are spliced into the battery cable, and flipping the mechanical switch "cuts" the cable. They can be mounted in the positive or negative side of the battery run. The switch isn't waterproof, so it needs to be out of the weather. This is what we'll be using for our install.
© Christian Arriero Should the Kill Switch Be Hooked Up to the Positive or Negative Side?
Super Chevy Week To Wicked 1969 POL Camaro build from start to finish!
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The internet loves to argue over whether it's better to hook up a master disconnect switch to the negative or positive side of the battery. Many stock-car rule books call for the switch to be on the negative side, while the NHRA demands it be on the positive side. So if you're putting in the switch to pass tech, you're going to want to do some reading of the rules before you start.
Some prefer to put the switch on the negative side for a safety reason. The theory is that the exposed terminals on the back of the disconnect switch could contact metal in a crash causing a short (and possible fire). This isn't a concern with the negative side since it's already grounded to metal. Of course, you can mitigate the risk of using the positive side by doing the install right.
© Christian Arriero No matter which side you choose, you'll need battery cables. Oh, don't cheap out here. We've seen a "bargain" battery cable that, when you cut it open, was junk with a really thick outer casing to make it look heavy gauge. This kit from Painless (PN 40105) came with 16 feet of positive and negative 1-gauge insulated copper cable. If your battery is going in the engine bay, they have an 8-foot kit, as well.
© Christian Arriero As you may have guessed by our cable selection, our battery is being mounted in the trunk, and that's also where we'll be putting our master disconnect switch. First up is getting our battery cable from the starter to the trunk, and for that we need a hole.
© Christian Arriero OK, safety talk time. It should be obvious, but when dealing with wires through metal it's imperative that you always protect those wires with a grommet. We've seen wires and even battery cables through bare holes, and it's just a few good rubs from a short and possibly a fire.
© Christian Arriero How and even where you mount your disconnect switch is up to you. We chose to fabricate a small L bracket and mount it in the trunk of our 1957 Chevy project, near the battery.
© Christian Arriero The positive cable was fed through the grommeted hole (to the starter), and we figured out where to make the cut. Measure twice since if you cut the end too short you're not going to be all that happy.
© Christian Arriero They make really cool battery cable snips, but a cutoff wheel works just as well.
© Christian Arriero After trimming back the insulation and sliding on a piece of heat shrink, we could put the copper lug in place. On short cables like this, it's important that the lug be clocked correctly since the cable is too stiff to twist very much.
© Christian Arriero Some people solder their lugs, some use pneumatic tools, but we love our hammer crimpers. There are a ton of different ones on the market, but they are inexpensive and do a great job securing the lugs to copper cable.
© Christian Arriero We've had ours so long in the MotorTrend Tech Center that we don't even remember where we got them. But they work great and even leave a positive or negative mark embossed in the crimp.
© Christian Arriero We could then slide up the heat shrink and hit it with our heat gun.
© Christian Arriero As you can see, we nailed the length and the clocking for our battery-to-switch positive cable. Now we just had to install copper lugs on the other cables.
© Christian Arriero For the negative side of the battery, our plan was to ground to the frame under the car. Like the positive side, we drilled a hole in the trunk floor, installed a grommet, measured how long a cable we needed, made a cut, and hammered on a lug with some shrink wrap.
© Christian Arriero We then passed the negative cable through the floor to where we had drilled a hole in the frame.
© Christian Arriero Yeah, we could have used a large-tapping screw, but a nicer method is to tap the hole and use a bolt.
© Christian Arriero According to Painless, the number one problem with electrical projects is bad grounds. So make sure there's bare metal under the lug and that you have the best possible metal-to-metal contact. If you want to protect the bare steel on the frame from rust, then use a dab of dielectric grease between the frame and the copper lug.
© Christian Arriero To secure our Optima yellow-top battery in the trunk of our 1957 Chevy, we grabbed this billet hold-down from Eddie Motorsports. Remember, if you are doing this to pass tech, then you need to read your specific rule book on trunk-mounted batteries since some sanctioning bodies require sealed battery boxes and might have other installation requirements.
© Christian Arriero We finished off our project by covering the positive battery cable to the starter with some of Painless' Powerbraid black covering. And just like that, we're done. With this system we'll be able to easily isolate the battery when the car is in storage to prevent any battery drain. Since the trunk locks, it's also a decent theft deterrent.
© Christian Arriero Remember, there are lots of ways to skin this proverbial feline, so figure out the best place for you to mount your master disconnect switch. It could be to the side of the trunk like in our '57, or you could figure out a bracket that lets you mount it to the battery like we did on this 1969 Camaro project. The important thing is to pick the master disconnect switch type that's best suited to your needs and to make sure all the crimps and connections are as rock-solid as possible.
SOURCES:
Eddie Motorsports
888.813.1293
eddiemotorsports.com
Painless Performance
800.423.9696|
painlessperformance.com
Optima Batteries
888.867.8462
optimabatteries.com