924Board.org

[daniel]

Hi All
I am installing a bettery cut out switch and ofcourse the alternator continues to run the engine after the battery is disconected. I have found a 3 terminal plug near the battery that has the same large black wire that goes to the alternator, but when I pull it the engine keeps going.

What is the easiest way to cut the power from the alternator and where do you get the wire from??

Thanks
Daniel
_________________
Over the top of skyline, total brake failure.... hit the wall at over 200 kp/h at the dipper, so anyone who has to brake for the esses is a pussy.
1977.5 Race Car, CAMS Group S Spec
1989 944 Cabriolet

[9XX Girl!]

OK Daniel

You don’t want to "cut the power from the alternator" while the engine is running. This will cause your alternator to hit a no load situation and could burn out your alternator field windings or regulator circuit.

The only benefit of having a battery kill switch is, if you crash and squash a starter lead or a big-ish cable against the bodywork or, have fire due to an electrical fault, you can cut the power.

If you are in an accident and the fire brigade turn up to cut you out or extinguish a fire. The first thing that they do is lift the bonnet (hood), and cut the battery lead with bolt croppers.

If you cut the battery lead while the engine is running, the engine will not stall. It will continue to run as the ECU /coil etc. etc. is still being fed by the alternator (which is really an AC generator with a solid-state rectifier and regulator installed in it). The load on the alternator can change suddenly in these conditions and burn out the field windings or armature windings.

The idea of a kill switch is to reduce the risk of fire in the event of an emergency. It will no stall the engine.

I have one fitted to my car. I kill the battery before I work on any of the electrical system. It also makes it easy to disconnect all electrical stuff when you have welding done. Surge spikes from a welder can fry your electrical stuff too

Put you kill switch between your neg battery terminal and the bodywork.

Paula
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924 (84) N/A 2 ltr - 5 Speed - BLACK - Project (looking for 200BHP, any ideas!)
924 (81) N/A 2 ltr - 3 Speed Auto - SURINAM RED (Metallic) - Near Original Spec (sticking with originality)
BOTH ON THE ROAD, BOTH USED EVERY-OTHER DAY

[pocketscience]

These work well and are easy to install. I know some guys have done the trendy looking isolator switch and mounted in the glovebox etc too...




G.
_________________
Whoever said you can't buy happiness forgot about Porsche!
81 924 N/A, GTS lights, Saratoga, interior, headers, Integral cam, EFI (sold)
95 993
69 911

[CorsePerVita]

Go the mad scientist route with a huge knife switch!

KILL ZEE POWAH! KILL EET NOW! MUAHAHAHAHA!

_________________
- 1977 Porsche 924 2.0 N/A (Trackday Project)
- 1979 Porsche 924 2.0 N/A (The other daily)
- 1980 Porsche 931 (Daily)
- 1987 Lamborghini Jalpa
- 1999 Ducati 900SS

[pocketscience]

[ideola]