theduck
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| posted on 14/4/14 at 03:30 PM |
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Battery cut off
Not for my kit but thought you guys would best to ask. I want to add a battery cut off to a car as an additional security measure and ideally wanted
to cut off just the starter. Can you recommend a suitable switch? Would there be any problems doing it this way?
Thanks in advance.
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theprisioner
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| posted on 14/4/14 at 03:51 PM |
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"this way" can you be more specific?
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http://austin7special.blogspot.co.uk/
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whitestu
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| posted on 14/4/14 at 04:00 PM |
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I've got one of these as it stops someone switching the hazards and lights on when I leave the car, plus it offers another, albeit small,
additional hurdle for a would be thief.
[img]
 
Description
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You could always just switch the starter solenoid.
[Edited on 14/4/14 by whitestu]
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theprisioner
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| posted on 14/4/14 at 04:18 PM |
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I used to have one of these several times, it will take the starter current. For track days I fitted one on the dashboard as a kill switch although
you have to have aux terminals so you don't kill the alternator should you operate it with engine running.
One of the key advantage is it makes your battery last longer in the winter as the standby current from the ECU and alarm systems etc is cut. But this
is a significant problem on some/most modern tin tops as the radio and things loose their memory. Some cars you cannot get into the boot open without
the battery connected.
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http://austin7special.blogspot.co.uk/
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britishtrident
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| posted on 14/4/14 at 05:07 PM |
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quote:
Originally posted by theduck
Not for my kit but thought you guys would best to ask. I want to add a battery cut off to a car as an additional security measure and ideally wanted
to cut off just the starter. Can you recommend a suitable switch? Would there be any problems doing it this way?
Thanks in advance.
If you just cut the starter they will just push start it.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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theduck
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| posted on 14/4/14 at 07:20 PM |
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quote:
Originally posted by britishtrident
quote:
Originally posted by theduck
Not for my kit but thought you guys would best to ask. I want to add a battery cut off to a car as an additional security measure and ideally wanted
to cut off just the starter. Can you recommend a suitable switch? Would there be any problems doing it this way?
Thanks in advance.
If you just cut the starter they will just push start it.
Good point!
Cutting additional circuits isn't a problem as will be circa 40years old.
Would putting th switch on the battery earth be ok?
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theprisioner
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| posted on 14/4/14 at 07:33 PM |
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If it is just an isolator then earth is fine, apparently you are supposed to disconnect the earth first (as recommended by some manufacturers), never
known why, perhaps one of the guru's can comment here. Configured as an FIA/MSA engine off it needs to be +ve as there is a ballast resistor
switched in for the alternator wind down.
http://sylvabuild.blogspot.com/
http://austin7special.blogspot.co.uk/
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SteveWalker
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| posted on 14/4/14 at 08:37 PM |
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I thought that the earth first was just for disconnecting the battery by undoing its terminals. The idea being that if while you are using a spanner
to release the clamping bolt, you catch it on the bodywork or the engine, it doesn't matter. Once the earth is off, it doesn't matter if
you do the same while removing the live connection.
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theduck
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| posted on 14/4/14 at 09:22 PM |
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quote:
Originally posted by theprisioner
If it is just an isolator then earth is fine, apparently you are supposed to disconnect the earth first (as recommended by some manufacturers), never
known why, perhaps one of the guru's can comment here. Configured as an FIA/MSA engine off it needs to be +ve as there is a ballast resistor
switched in for the alternator wind down.
Thanks, I will do it that way then. It really is just has an extra anti theft device as I am now slightly paranoid having had a car stolen after they
broke into our house and took the keys. I figure if it happens again this might be enough to confuse them and not lose the car!
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SteveWalker
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| posted on 14/4/14 at 09:26 PM |
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I'd be tempted to fit a timed relay for the ignition and fuel pump and a hidden switch. Without knowing about it, they'd start the car,
maybe just about set off and then the engine would cut out. Hopefully they'd think that there was something wrong with it and abandon it.
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Canada EH!
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| posted on 14/4/14 at 09:34 PM |
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Nothing draws attention like a car sitting in the middle of the road.
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unijacko67
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| posted on 14/4/14 at 10:34 PM |
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While there are a few knowledgeable chaps on this thread could I ask what the best way of fitting the fia swich for log book compliance.
I already understand the main live cable should be swiched via the isolator and the alternator should be earthed.
Do I earth the alternator live via the smaller terminals to send that wire to earth when the switch is in the off position.
Also will there just be one live/charge wire from the alternator that I need to earth via switch/off as I believe the Honda S2000 has a fancy charge
system or is there an easier way.
I have also been told that it can be done at the ecu so I'm a bit confused and don't want to cause any damage.
Any help and advise will be greatly appreciated.
http://www.kittenkitcar.co.uk
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theprisioner
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| posted on 15/4/14 at 08:44 AM |
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The hazard you are trying to protect against is the alternator going o/c while the engine is running. This causes high voltages to be produced by the
alternator. To protect against this an extra set of contacts switches in a ballast resistor to protect it on run down (when switched off). The extra
set 2 pair) are a normally open set of contacts and a normally closed set and should be wired as follows:
 
FIA switch
Obviously the contacts to the resistor are normally closed when the key is out or in the off position.
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http://austin7special.blogspot.co.uk/
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daveb666
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| posted on 15/4/14 at 10:13 AM |
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If it's just anti-theft then why do you need to go to the effort of switching the major circuits?
Just fit a flip switch (or two) under the dash; one for your fuel pump, and one for your ECU (or similiar).
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DW100
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| posted on 15/4/14 at 12:02 PM |
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If you are going to fit the cut off in the earth lead think about it carefully as if you get it wrong and try to start it the engine could try to find
an earth path through something like the throttle cable.
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unijacko67
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| posted on 15/4/14 at 09:18 PM |
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quote:
Originally posted by theprisioner
The hazard you are trying to protect against is the alternator going o/c while the engine is running. This causes high voltages to be produced by the
alternator. To protect against this an extra set of contacts switches in a ballast resistor to protect it on run down (when switched off). The extra
set 2 pair) are a normally open set of contacts and a normally closed set and should be wired as follows:
FIA switch
Obviously the contacts to the resistor are normally closed when the key is out or in the off position.
I take it the contacts are open on the other two terminals (ignition to coil) when the key is out. Done most of it tonight and fitted the resistor,
but havent done the ignition to coil wire as yet and it does indeed run on.
http://www.kittenkitcar.co.uk
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theduck
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| posted on 15/4/14 at 09:28 PM |
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quote:
Originally posted by daveb666
If it's just anti-theft then why do you need to go to the effort of switching the major circuits?
Just fit a flip switch (or two) under the dash; one for your fuel pump, and one for your ECU (or similiar).
Because the battery cut off style switches have a removable "Key" which i can keep separate to the car keys
quote:
Originally posted by DW100
If you are going to fit the cut off in the earth lead think about it carefully as if you get it wrong and try to start it the engine could try to find
an earth path through something like the throttle cable.
Thats also a good point. Will seek further advice once I have decided on and purchased a car.
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snowy2
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| posted on 15/6/14 at 06:02 AM |
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My first kit car was in 1986 and i fitted a battery isolator as well as hidden switches for security and i used to fit them to my kit cars for quite a
while afterwards. i dont bother any more. the fact is that kit cars are rarely stolen, its one of the major reasons why our insurance is so low.
sometimes you are the pigeon, most of the time the statue.
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