6 pole cut off switch and clock/radio memory - impossible?

[pitsqrd]

I have been searching the forum for a couple hours and can't find any indication anyone has been able to install a 6 pole cut off switch and still able to maintain clock radio memory and or alarm when the switch is off (i.e. battery pwr cut off).

I tried installing a 3 amp in line fused wire directly from the + batt post to the input line (bottom of fuse at fuse box) of the clock to by pass the switch. The clock continued to operate when the switch is off and disconnects the battery, but after about a minute or so, the grounding resistor attached to the #1 terminals of the switch intended to absorb the alternator spike gets extremely hot. I am fairly sure this is because there is a current path from the 3 amp fused wire I installed from the + battery post to the clock back through the #1 terminals the resistor and to ground.

In a general internet search I found several people saying a 3-5 amp in-line fuse across the main switch terminals (the terminals that cut the + side of the batt, when switch is off) would work, but I think they were using a cut off switch that does not have the alternator spike protection terminal (pole) in the switch that is connected when the switch is in the off position.

Has anyone been able to hook up a 6 pole batt cut off switch as shown below and still maintain the clock, radio memory and alarm when the switch is in the off position?

Thanks in advance

[winders]

Well, you are trying to do something which goes against the whole point of the switch.

What you need to do is put a diode between where you splice in the +12v wire and the wire going back to the rest of the car's electrical system. The diode, installed in the correct orientation, will allow current to flow to the clock but not back past the diode. I would splice the =12v from the battery+ terminal after the fuse in the fuse panel.

Here is a crude text diagram:

              Wire to battery+
                     |
                     |
                     |
CLOCK------------------------------Diode--------------------Fuse Panel

I am not an expert on diodes so you will want to work with someone who knows what they are doing with diodes to get this all correct.

[dad911]

Instead of using the switch to ground out the system and cut ignition, use it to turn off the fuel pump relay, that will still cut the engine.

[HorstP]

Originally Posted by dad911

Instead of using the switch to ground out the system and cut ignition, use it to turn off the fuel pump relay, that will still cut the engine.

That answer does not seem to make sense to me. Whatever you do to kill the engine, you still want to disconnect the battery. That + killing the engine is the whole purpose of the switch. And whenever you disconnect the battery, you want to add the grounding of the positive rail to save the generator.

[911pcars]

That switch type is required for most racing bodies; externally mounted to kill the vehicle's electrical system in case of a track collision and without driver assistance. If that's the purpose, you don't want to override it with bypass circuits.

If, however, you want to use that switch to keep selected circuits active during storage, the suggestions are okay. However, shunting charging current from the alternator is not a concern in a typical Engine OFF storage environment.

However, you can accomplish the same result with a simpler $4 battery post cutoff switch from Harbor Freight. Use the enhanced type or upgrade it so it includes a low current, fused bypass circuit to maintain current to radio preset and clock circuits.

Sherwood

[rbogh901]

Originally Posted by 911pcars

However, you can accomplish the same result with a simpler $4 battery post cutoff switch from Harbor Freight. Use the enhanced type or upgrade it so it includes a low current, fused bypass circuit to maintain current to radio preset and clock circuits.

Sherwood

How do you prevent battery drain from sources other than radio/clock?

[HorstP]

or more to the point. Running a fuse in parallel to the battery post cut-off switch makes it totally useless.

[911pcars]

Originally Posted by rbogh901

How do you prevent battery drain from sources other than radio/clock?

Normal or abnormal battery drain?

Normal current drain shouldn't exceed 6 milliamps. or thereabouts. If normal current drain discharges the battery (clock, radio presets, alarm system, etc.), I would examine each of these and determine if any of these individual circuits is using excessive current at rest.

If the at-rest system current flow is abnormal, there's a malfunction in the elec. circuit. Find threads explaining/finding "parasitic current drain" using an independent search engine (better results than Pelican's. Preface with "Pelican current drain ......").

If the battery discharges overnight, disconnect the ground battery cable and place a battery maintainer on the battery between uses until the malfunction is diagnosed.

Sherwood

[RSBob]

Uh, how about running separate fused + wires to your clock and radio directly from the + battery terminal? Too simple?

[winders]

Originally Posted by RSBob

Uh, how about running separate fused + wires to your clock and radio directly from the + battery terminal? Too simple?

Excellent suggestion. I was thinking, after I made the diode suggestion, that he might as well hook straight to the battery and bypass the regular car wiring altogether. Didn't have a chance to post that....you beat me to it.

[Walt Fricke]

Devices you rewire so they come from the battery plus side, either directly from the battery, or from the battery side large pole on the cut-off switch, ought not to have a sneak path back to the alternator/main current feed side of the electrical system. You'd just have to be careful that the positive sides of these don't connect elsewhere to that side of things. Because the only current source for the resistor ought to be the residual current coming from the alternator as it winds down.

It kind of defeats the purpose of the kill switch, though, if you leave other wires hot with the switch off. The switch is there for corner workers to turn off the engine (if it hasn't done that itself, or you haven't turned the key off), but also - once that is done - to reduce to a minimum the length of any wire still "hot." Ideally, only the wire from the battery to the switch would be a residual source of short circuits and thus of ignition sources.

[911pcars]

Originally Posted by winders

Excellent suggestion. I was thinking, after I made the diode suggestion, that he might as well hook straight to the battery and bypass the regular car wiring altogether. Didn't have a chance to post that....you beat me to it.

Lacking confirmation from the OP, it sounds like this "race switch" is not for a dedicated track car, unless smooth sounds from the audio system are an integral element in clicking off fast lap times.

Piling on additional circuit wires onto the battery post is poor electrical practice. That's why there's a fuse box, to apportion like accessories with a common fuse along with other circuit fuses in a central box/location.

The simple cutoff switch I mentioned earlier uses a low current bypass wire and inline fuse that bridges the cutoff switch in order to provide low amperage electricity to the system clock, radio presets, etc. Since the fuse in this circuit reflects the low current flow, an attempt to crank the engine with the switch in the OPEN position will blow the fuse as a result of high starting current attempting to flow through the bypass circuit to the starter.

Sherwood