Remote battery disconnect switch

The second picture (the black one with the red removable key) I've seen installed on race cars, to kill the power. In fact, in some classes, even on stock racing vehicles, that switch is required so that in the event of a crash, rescue workers have a way of killing the power externally. The first one (metal case), I haven't seen, but probably is essentially the same.

I think the trick with these switches is to make sure that they are rated to handle well more than the maximum amperage you will be putting through them. I'm sure they all list that rating. Not sure what kind of car you are looking to install it in, but many cars, like the 328s and later 308s and beyond, have cut off mechanisms built in. Of course some, like in the Mondial QVs that I've seen, are crappy twist switches that corrode and cause significant problems.

Oh, and those switches are usually installed in the negative/ground line to the battery, not in the postive cable, if I recall correctly. In the 328 I have, it's in the negative, and the green knob cut-offs that go on the battery are always installed on the negative terminal.

 

Another option is Ferrari part 139607

Many many Ferraris over the years have them as standard

 

Generally, a mechanical battery cutoff switch should always be installed in the negative ground cable. If installed in the positive cable, a short could lead to a catastrophic battery discharge/meltdown.

If you need a remote switch, consider something like this:
http://www.summitracing.com/parts/SMS-333126/

Cheaper than the Ferrari switch as well.

 

I think I remember Painless Wiring had one

 

That switch, 139607, was the type of switch that was on the Mondial QV I had. But the one on my Mondi was ancient and not was completely corroded. I simply by-passed it, which solved a lot of electrical problems in that car. I did not look for a replacement, but I assume that's it. Just curious, what does that go for? I'm sure it's not in the $10 or $15 range.

 

139607 is $114.50 at Ricambi. Ferrari tax. Lot cheaper ones (and just as good) at Summit Racing.

 

Just a couple of quick comments...

Firstly, I agree with what everyone's said so far... good advice. I think the Battery Brain is a sensible solution if you're going to remotely operate it, for the following reason:

My understanding is that the battery brain uses a wire carrying low current to switch a much larger current -- think of it as a fancy relay. This keeps the actual high-current switching component right near the battery, thus isolating more wiring from the battery and ensuring that you don't have conductors and contacts in the cockpit that would dump potentially 1000's of amps if shorted to ground. (And this latter point is why disconnecting the negative lead near the battery is preferred with the chassis at ground potential.)

I would be really concerned about having a traditional high current switch in the cockpit for that reason. There's an old saying in the reliability engineering community: "Don't confuse the unlikely with the impossible." I think you'd have to go to great pains to do the traditional disconnect switch in the cockpit and feel safe for any contingency. Another thing is terminating these big wires... hard to do it yourself as the crimping dies are big and expensive and you'll generally need a hydraulic press for those terminations.

If you do use a traditional switch, locate it as physically close to the battery as possible. I'd fabricate a custom bracket if there is presently no mounting provision. Don't skimp. Consider guarding the terminals on the switch with insulating material.

And regarding traditional switches... if you go this route do consider stuff intended for boats. I think it's a cut above most of the automotive stuff as it needs to be reliable in a condensing atmosphere and maybe salt water exposure. Defender, West Marine and other boating supply places have good switches. Note that most of these are "bulkhead" or "flange" mount... the bigger ones do not rely on a threaded tube around the switch shaft for mounting. See attached picture I grabbed from Defender's page: that's a Blue Sea Systems 550A continuous switch rated for 1200A cranking current. It's under $US 70... a bargain I think. (It's the one I'm using). Note also that with one of these near the battery you can buy short pre-terminated battery cables to connect it at any auto parts place.

Gotta dash... hope this is of some help...

Charles
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Very interesting post and good idea to use marine grade stuff.

 

I have used both of the ones you pictured, mostly the first one (it is OEM in Freightliner trucks) Works fine, I have a Perko in my boat but it is big and bulky, prefer not to use something like that in my Ferrari. http://www.perko.com/catalog/category/battery_switches/product/150/

 

Don't do this unless you thought this out. There is a difference between a battery disconnect switch and a kill switch. We use the kill switch in racing. You need to ground out the alternator in a kill switch but not in a disconnect switch. If you use a DS as a KS your car will run through the alternator and no shut off. Some modern Ferraris do not like this and suff in them blows up because ferrari electronics is so bad. So you can use the two post as a DS but you need a 4 post like this as a KS. Anything inside a car interior is usually a KS. Anything under the hood or in a remote location is usually a DS. Hope that helps.
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Craig:

If I am not mistaken, the switch that Fatbilly shows connects and disconnects BOTH positive and negative wires. This would make the most sense from a safety standpoint to have the switch inside the passenger cabin of the vehicle and would be a true disconnect switch.

Does your car have enough of a drain to warrant disconnect switch? Or are you doing it for other reasons (fire safety, security?)

I leave my car on a battery tender type device 100% of the time (well, unless I'm driving it, I can't find a cord long enough for that) and have never had an issue. In fact it's the one of the best $50 I've spent on the car. The car always cranks when I go to start it, whether it's been 1 week or 6 months.

 

Craig,

Check the info on Battery Brain. What I saw, it mounts on the positive terminal of the battery. Not sure if you can mount it remotely in the negative line hidden off somewhere. You might want to check that out before going to the expense and bother.

 

Which cable to sever depends on the OEM set-up. When you install these you want to think chess not checkers. My initial thinking is to sever the positive. The reason is in racecars we worry about electrical fires igniting fuel especially in crashes where you are trapped in the car. If you sever the ground and the car gets bent in a crumpled mess what if some of that metal is touching the battery negative and complete the circuit or the battery shifts in the tray? You then are live electrically. This can happen on the positive too and short but it seems that the negative is more often the one that finds its way to ground most often. I think more important that which wire you cut is to cut the power as close to the battery as possible not for your convenience. You can run a pull cable into the interior to kill power at the switch. All KS have a hole in the key for this reason and it is way easier to run a pull cable into your dash than two 4Gage cables from the battery to the KS on your dash and that cable is heavy and slows your racecar down. Putting the KS nearest the battery cuts down on possible places a crash can help make a complete circuit. It is also import that you fix your fuel smell. Ferraris seem to various fuel tank issues that are fixable. For example, 348's seem to have some purge valve/charchol cansister issues and 550's seem to have some gaskets that don't like our reformulated ethanol fuels. The good news is that those issues are easy to fix.

 

Click/clack

 

Has anyone experience with a remote controlled battery disconnect switch? I assume it gets its power from the battery, so is there still a risk of draining the battery? My battery is hidden below the spare tire so difficult to reach. I've tried a battery tender, but it's a hassle and I have to crack open the sunroof to get the tender cable inside the car. A remote controlled switch seems like a very elegant sollution and I don't have to mess with the car's interior.

I'm talking about something like this:


Pricing is all over the place (from very, very cheap to expensive).

 

+1 I don’t want to reprogram the radio every time and set the clock

 

I do use a FIA certified switch.

• It is on the positive side.
• it does not toggle the starter cable
• It is bypassed for the clock
• as it is inside the cabin, I've trimmed the key so as to make it less bulky and reduce the risk of accidentaly disconnecting the battery.
• I've added a big capacitor, just in case the battery gets disconnected while the engine is on.

My car is vintage, I've had some bed experiences with the OEM Ferrari kill switch (the one with the grey key). Not sure how the new Ferrari ones compare, but the certified switch has been bulletproof so far (installed in 2008).

 

Do you have a link for that item that you posted? That looks more like something to remotely connect/disconnect a small item using only a relatively small current (not be a true battery disconnect switch capable of running the starter).

 

https://www.ebay.nl/itm/256706316294

12V Wireless Dual Remote Car Battery Disconnect Relay Master Kill Cut-off Switch

• This is a convenient battery disconnect switch system that allows remote master control to turn off your car's power system. It can prevents battery drain,also be used as an anti-theft measure.
• The remote battery disconnect switch universal for DC 12v camper trailer suv truck auto off road rv atv car motorcycle and so on.
• Easy to install,connect the red wire to the positive pole of battery, black wire to the negative pole of battery.
• Package Included: 1*Battery Isolator switch, 2*Remote Control, 2*Positive/Negative Wires, 2*Copper Sheet,1*Battery Clip,1*Bus Clamp.
• Working Voltage: 12V
• Rated Current: 200A
• Instantaneous Current: 800A

Package includes
1 x Car Battery Disconnect Switch
2 x Remote Controls
1 x Battery Clip
1 x Copper Sheet
1 x Control Cable

 

For what car? I can't see it fitting above the battery on a lot of Ferraris.

Doesn't look very robust. especially on that single copper lug side. Usually you'd need a special power crimper. What's the lug supposed to hook up to? Your old positive battery lead (floating in the breeze)?