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Which kill switch 75 or 100A


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As per title, looking at fitting a Durite kill switch with on/off removable key. There seems to be a choice of x2 75amp or a 100amp rated which do i need for a 300tdi 90 it has no winch just standard electrics?

Cheers for any advice or help Mutley

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The bigger the better.

Remember that it needs to be a 4-terminal switch - 2 big ones for the battery and 2 smaller for the ignition/FIP-solenoid - you also need an alternator "dump" resistor otherwise if you activate the switch with the engine running at significant RPM then the alternator's disconnected from the battery so its output has nowhere to go and this can wreck both the alternator and other electronic devices with over-voltage spikes.

Look for something described as a "FIA" battery switch for details.

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Ok please forgive my ignorance, but as i understand it a 300tdi can be bump stated? If this is the case is it worth the extra trouble of conecting the lill switch up to the FIP?

And what is an alternator "dump" resistor?

cheers

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A 200/300TDi can be bump-started but it needs the FIP stop-solenoid plunger removing first.

As standard, a 200/300TDi, once started, will continue to run if the battery's disconnected - the alternator provides power to the FIP stop-solenoid to keep the fuel supply going. (Other electrical systems like radios, satnavs etc may be damaged if you do this because without the battery being connected the alternator's voltage can cary widely).

Bump-starting is not what kill-switches are about though. They're about stopping the engine safely.

The proper isolator-switches - 4-terminal ones - have, as well as the big terminals for the battery/starter circuit, 2 small terminals you wire in series with the ignition/ECU [on petrol engines and common-rail electronic injected Diesels] or the FIP solenoid [clockwork diesels] so when you turn the switch it kills the engine as well as isolating the battery. This reliably kills the engine and is mandatory for most forms of competition - a marshal *must* be able to stop the engine and isolate the battery from outside the vehicle in case of emergency (such as when you've had an "off" into the shrubbery, you're now upside-down in a ditch and the driver/co-driver are unconscious or dangling from their harnesses like confused orang-utans).

The alternator "dump" resistor provides somewhere for the volts to go in the time between the switch being triggered and the engine actually stopping, so the over-voltage from the alternator doesn't wreck your electronics.

You can mount the switch anywhere you like - aim to minimise the length of additional thick cable you need to use - and use a 'pull' handle which looks like a bonnet-release cable with a red T-shaped handle - fitted to the outside of the vehicle to activate the switch. External handle should be suitably marked: http://d121tcdkpp02p4.cloudfront.net/clim/28823/Battery-isolator-external-pull.JPG

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Ok, ok I've been "TOLD!" the FIA one it is!.......

Thanks for the well informed reply Tanuki, as the Defender is never used in competitions and the kill switch was just for security purpose I don't think I need the pull handle?

Can you point me in the right direction of a good dump resistor to use and where I might get one from plus how much of a head ache will this be to install ie so it cuts out the FIP and keeps the alternator safe, is it follow diagram or do I have to scratch my head (which still hurts from wiring in the spot light bar)???

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Yes just get a standard "FIA" compliant master switch - which should include the dump-resistor - and wire it as designed.

You don't need the external marshal-controllable T-handle-and-cable if you're not running in any RAC MSA sanctioned events. I'd put the kill-switch on the face of the seat-box (assuming your battery's under the seat).

Remember that a "kill switch" that disconnects the battery also disconnects any alarm/immobiliser you may have fitted!

A lot of better alarm/immobilisers (I think this is a requirement of anything "Thatcham" approved) have a separate built-in battery to operate their sounders - and will treat a sudden disconnection of the main vehicle battery as "tampering" so they'll sound-off.

Disconnecting the battery will also lose you any saved presets and the time on your radio.

For security a proper alarm/immobiliser's better than a kill-switch. A proper immobiliser *and* a Rottweiler is better still.

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If it's just for security, you don't need a kill switch, you just want an isolator. I would look at the Albright isolator solenoids, they're not much money and it means instead of having a great big kill switch everybody can see fitted only where you can route thick battery cable to, you can have a little switch of your choosing fitted wherever you like.

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If it's just for security, you don't need a kill switch, you just want an isolator. I would look at the Albright isolator solenoids, they're not much money and it means instead of having a great big kill switch everybody can see fitted only where you can route thick battery cable to, you can have a little switch of your choosing fitted wherever you like.

Next time you see my Defender. See if you can find the FIA switch fitted on mine.There's nothing big IMO about 3/ 8 " X about half inch.

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If you run the positive from the alternator direct to the battery or battery side of the switch it solves all the above problems. As when you flick the switch the alternator power is going to the battery not the stop solenoid or anything else thus the engine dies.

Mike

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