Printable Version of Topic

Click here to view this topic in its original format

914World.com _ The Paddock _ Battery cut off switches

Posted by: CG-914 Jun 2 2020, 02:30 PM

I want to instal original Bosch cut off switches, like on the original 914GT. One on the tunnel and one under the windshield driver side.

Does anybody have directions for the wiring?
Do you run from the battery all the way up front and back to the starter?

Attached Image

Posted by: stownsen914 Jun 3 2020, 05:40 AM

One thing to note about the older two pole style cutoff switches is that they don't protect your alternator if you ever need to shut off the engine while the car is running. The voltage spike from the alternator still spinning after the battery is taken out of the circuit can ironically ruin the alternator.

Posted by: windforfun Jul 19 2020, 06:25 PM

This is excellent input. Smart, smart, & smart. From an EE perspective, I would keep it to one switch with short wiring (no pun intended). You have to run the battery cables like you suggested. I suppose a relay might work if it can handle the current. Can the coil be switched off instead?

Posted by: BillC Jul 20 2020, 07:08 PM

If you want to have a single cutoff switch but multiple places from which it can be activated, take a look at the Cartek GT cutoff switch. It's a solid-state switch that uses normally-closed, momentary-off switches to activate or reset. I put one on my Spec Boxster, and it's been great.

Pegasus Auto Racing sells them:
https://www.pegasusautoracing.com/productdetails.asp?RecID=24996

Or, if you don't mind ordering from the UK, Demon-Tweaks has them cheaper, including shipping:
https://www.demon-tweeks.com/us/cartek-gt-solid-state-battery-isolator-kit-242156/

I ordered mine from Demon-Tweaks, and it took just over a week to arrive, but that was pre-pandemic.

You can also order extra switches from either site.

If you want the look of the old-style cutoff switches, you could modify them internally to act as a momentary-off switch to trigger the cutoff.

Also, the Cartek GT has a positive output lug that cuts off 1/10 sec before the main cutoff. I use it to drive a relay that turns off my ECU before everything else is shut off. You could use it to drive a relay to connect/disconnect the alternator output instead.

Posted by: mlindner Jul 22 2020, 09:04 AM

I installed mine in the rear over the old battery location, battery will be in the trunk. Best, Mark

Posted by: infraredcalvin Jul 22 2020, 01:23 PM

Mine is in a similar location behind the sail panel on passenger side, battery is in the trunk. The only downside is when I get in the car, buckle up and realize I’d forgotten to switch on... then is when I wished I had one in reach of the drivers seat.