Battery disconnecting switch

mnmk · Post by **mnmk** » 29 Jul 2017, 08:42

Hello.
Has anyone installed a battery cut off or disconnect switch in the engine compartment?
Is this even a possibility?
Thank you.

Georgeandkira · Post by **Georgeandkira** » 29 Jul 2017, 10:03

The battery main (red) cable comes up to the little trap door from below. The access is a little cramped.
I installed one years ago in a '72 Corolla (battery under the hood). There was a knob you unscrewed and a blade connection you pulled apart.
I rigged a dummy red cable so if someone opened the hood and remade the connection they'd get nothin'
The real starter motor cable was tucked away out of sight.
I'm so cool.

Post by **abscate** » 30 Jul 2017, 05:11

Why do we only get NJ people posting in the theft threads?

On a P2 chassis, disconnecting the battery resets a bunch of stuff like dour locks, sunroof, engine adaptives, that won't be happy. We get a lot of reports here of funkiness after battery jobs. Your ECU has to relearn its fuel/air curve each time you disconnect the battery. Your ECU also resets the emission testing cycles each time , too.

If you move three hours up the Hudson, you can leave your keys in your car, and our Governor doesn't close our beaches so he has more space.

Post by **precopster** » 30 Jul 2017, 05:51

To answer the question you can install a cutoff switch on the red cable on the way to the starter on a P2 because it branches off at the jumper point to fuses and the rest of the system. The solid red cable only serves the starter system on P80s as well so a switch in series with this cable is fine and will still allow power to computers and ignition systems.

You would need heavy terminal lugs and a crimp tool to fit the type below.

The switches that go on top of battery terminals aren't suited for the reasons Abscate mentioned above.

Georgeandkira · Post by **Georgeandkira** » 31 Jul 2017, 06:52

abscate said, "Why do we only get NJ people posting in the theft threads?"

I was living in NYS at the time. Nya, nya, nya! Kira

Post by **abscate** » 31 Jul 2017, 10:16

Georgeandkira wrote: ↑31 Jul 2017, 06:52 abscate said, "Why do we only get NJ people posting in the theft threads?"

I was living in NYS at the time. Nya, nya, nya! Kira

Oh, go sit on the beach - wait - theres no room - theres a BFWG taking up all the space.....

LOve ya, Garden Staters...and stop coming up here and wondering why you have to pump your own gas...

Georgeandkira · Post by **Georgeandkira** » 31 Jul 2017, 16:06

I'll be swinging by your neck of the woods pretty soon Steve. Looking forward to meeting you.
As far as the BFWG goes; they floated the idea of making him a sportscaster and surprisingly enough, the usual "red, white and blue and better than you" crowd rejected him.
Christie icing on the Trump cake was just too much. Cheers G&K

Post by **abscate** » 31 Jul 2017, 20:03

I'm Dr Dad this week, kids are home and Dr Mom is out, I am in Albany rest of week
K

Post by **jonesg** » 01 Aug 2017, 18:54

mnmk wrote: ↑29 Jul 2017, 08:42 Hello.
Has anyone installed a battery cut off or disconnect switch in the engine compartment?
Is this even a possibility?
Thank you.

They use a lot of those switches on boats, the ones that don't require a wrench to tighten can vibrate loose and cause trouble.
Might boil a battery or freak out diodes in the alt.
Not sure what the upside is in a car, boats rely on dual batteries.
I see marine batteries with wing nuts on the terminals, its a really stupid idea.

Post by **precopster** » 01 Aug 2017, 19:27

jonesg wrote: ↑01 Aug 2017, 18:54
mnmk wrote: ↑29 Jul 2017, 08:42 Hello.
Has anyone installed a battery cut off or disconnect switch in the engine compartment?
Is this even a possibility?
Thank you.
They use a lot of those switches on boats, the ones that don't require a wrench to tighten can vibrate loose and cause trouble.
Might boil a battery or freak out diodes in the alt.
Not sure what the upside is in a car, boats rely on dual batteries.
I see marine batteries with wing nuts on the terminals, its a really stupid idea.

If you fully understand which circuit these switches are cutting as in my post they can't possibly damage any other device. If you cut power to starter then you cut power to alternator as they're bridged at the starter. Car doesn't start with switch open so therefore you can't stop the alternator doing its job or upset the charging circuit because alternator is not turning. Switch it on then car starts and allows alternator to do it's job because the switch is closed. Simple.