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Thread: HELP - Fitting a Battery Isolation Switch

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    Apprentice mamonem's Avatar
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    Default HELP - Fitting a Battery Isolation Switch

    Hi,

    I'm looking to install a Battery Isolation Switch. Reading through the forums, I've determined the following. Can somebody verify my thinking is correct and point out any errors.

    I can purchase a Heavy Duty Switch with key from here or somewhere similar, and this will not only provide a locking switch but also avoid some of the wear i've heard about on the Red Key ones.

    I'd mount the switch whereever I want, BUT, most recommend near the passenger side seat as its nearer to the battery. I'd then Disconnect the +ve side of the battery and this would be extended to go to one side of the switch, with the otherise of the switch going back to the battery terminal.

    If I wanted to maintain a low current for lights etc, I could put a 5amp fuse or similar between the two terminals on the switch.

    SO my shopping list would be

    2 x Battery Extension Cables (16mm) to go from existing cable to switch and then switch to battery
    1 x Switch

    Does this all sound right?
    Rgds,

    Mark

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    Default Re: HELP - Fitting a Battery Isolation Switch

    Quote Originally Posted by mamonem View Post
    I can purchase a Heavy Duty Switch with key from here or somewhere similar, and this will not only provide a locking switch but also avoid some of the wear i've heard about on the Red Key ones.
    Note that this switch has no alternator protection - I'll come back to that. Also the 'key' isn't s multi-pattern security key, but a design common to every switch of that type made - so not really any more secure than the 'red key' types.
    Also, you really need to secure the seat box cover down - otherwise someone can just lift the lid and stick any old bit of metal across the switch terminals.
    I'd mount the switch whereever I want, BUT, most recommend near the passenger side seat as its nearer to the battery. I'd then Disconnect the +ve side of the battery and this would be extended to go to one side of the switch, with the otherise of the switch going back to the battery terminal.
    I'd expect the existing cable to reach the switch - you'll just need to remove the battery terminal. Other than that, yes it should work just like you say.
    If I wanted to maintain a low current for lights etc, I could put a 5amp fuse or similar between the two terminals on the switch.
    It's more important than that, and needs to be larger than 5A. If you ever forget and pull the switch with the engine running, or a passenger catches it with his feet*, etc, etc then you are disconnecting the battery. You don't say what motor you have, but early ones tend not to have a lot of "base load", and later ones have sensitive electronics. The battery is an essential part of the system as it absorbs excess charge from the alternator - eg you switch the headlights off and dump 10A (could easily be 20A, 30A or more with extra lights etc), the alternator takes a finite time to reduce it's output and in the meantime it is only the presence of the battery that keeps the system voltage from spiking and blowing the electronics (including diodes in the alternator).

    Realistically you need something like a 30A fuse - that should handle most 'normal' operations, but will blow immediately if someone tries to start the engine with the key out.
    SO my shopping list would be

    2 x Battery Extension Cables (16mm) to go from existing cable to switch and then switch to battery
    1 x Switch

    Does this all sound right?
    Yup

    * Caught me out once. Had a Mk1 Escort when I was at university, and a 'red key' FIA style switch in the dashboard where it was convenient to bring the battery cables through. Going up a steep winding hill in Wales with a car full of others, all on our way to spectate on a rally, it just went dead. Cut out, no power, nothing. So I'm left there, blocking an A road on a steep corner

    Took me a while to figure out the passenger had knocked the isolator out with his knee

    It did do it's job though, being black, in a black dashboard it just looked like a socket to anyone not familiar with them. And I know for a fact that someone was 'confused' by the electrics at least once - they showed their confusion by fetching all my extra wiring down from under the dash.
    110 V8 LPG, 90 2.5 Petrol (no longer turbo diseasel )
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    Mechanic PaulMc's Avatar
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    Default Re: HELP - Fitting a Battery Isolation Switch

    Quote Originally Posted by mamonem View Post
    Hi,

    I'm looking to install a Battery Isolation Switch. Reading through the forums, I've determined the following. Can somebody verify my thinking is correct and point out any errors.

    I can purchase a Heavy Duty Switch with key from here or somewhere similar, and this will not only provide a locking switch but also avoid some of the wear i've heard about on the Red Key ones.

    I'd mount the switch whereever I want, BUT, most recommend near the passenger side seat as its nearer to the battery. I'd then Disconnect the +ve side of the battery and this would be extended to go to one side of the switch, with the otherise of the switch going back to the battery terminal.

    If I wanted to maintain a low current for lights etc, I could put a 5amp fuse or similar between the two terminals on the switch.

    SO my shopping list would be

    2 x Battery Extension Cables (16mm) to go from existing cable to switch and then switch to battery
    1 x Switch

    Does this all sound right?

    Sounds about right... But, I would use at least 35mm Battery Cable and probably a 15amp fuse for the alarm, radio memory, parking lights, etc...


    Paul.
    Paul.

    1989 Arles Blue 2.5TD 110 Hardtop
    1999 Epsom Green Discovery II 4.0 V8i 'XS'



    Land Rover Connectors & Terminals

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    Default Re: HELP - Fitting a Battery Isolation Switch

    IFAIC you are wasting your time fitting anything other than a FIA battery master switch. Unles you want to burn your alternator out if the switch gets knocked off accidently..
    Key wear ? Who gave you that stupid idea ?? Of course what would I know having fitted an FIA awitch in 2003 and still using the same key daily.

    The FIA switch is the only switch that CAN'T be overridden.

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    Default Re: HELP - Fitting a Battery Isolation Switch

    Quote Originally Posted by mmgemini View Post
    IFAIC you are wasting your time fitting anything other than a FIA battery master switch. Unles you want to burn your alternator out if the switch gets knocked off accidently..
    There are other ways ...
    Key wear ? Who gave you that stupid idea ?? Of course what would I know having fitted an FIA awitch in 2003 and still using the same key daily.
    It is actually a real issue. Surprisingly it's the metal bit that wears - the little brass pin. Last time I had one getting a bit weak, I knocked the pin back and turned it round a bit. When they wear, contact becomes a bit erratic, and they burn out the resistor as it stays powered on with the key in.
    The FIA switch is the only switch that CAN'T be overridden.
    That is complete rubbish - I'll show you how to override one in seconds if you like, with absolutely no special tools.
    110 V8 LPG, 90 2.5 Petrol (no longer turbo diseasel )
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    Default Re: HELP - Fitting a Battery Isolation Switch

    I've recently installed one of VWPs Security Isolator switches which has a "proper" key which is removable so there is no chance of knocking it off accidently. The switch is inside my lockable cubby box with the terminal connections between the bottom of the cubby box and the seat box cover, try getting to that to bypass in a hurry
    1994 300tdi Defender 90 Hardtop
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    Default Re: HELP - Fitting a Battery Isolation Switch

    Quote Originally Posted by SimonHobson View Post
    There are other ways ...

    It is actually a real issue. Surprisingly it's the metal bit that wears - the little brass pin. Last time I had one getting a bit weak, I knocked the pin back and turned it round a bit. When they wear, contact becomes a bit erratic, and they burn out the resistor as it stays powered on with the key in.

    That is complete rubbish - I'll show you how to override one in seconds if you like, with absolutely no special tools.
    I'm home all weeked. please call ansd shew me. Nobody else can and I certinlty can't.

    Although as I said and keep saying what would I know about any of this including eight years rally car preparation.

    Of course the keys are SO expensive. Well they are afor sombody on 100 a week paying 60 tax......

    NOTHING IT SEEMS.

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    Default Re: HELP - Fitting a Battery Isolation Switch

    Quote Originally Posted by mmgemini View Post
    I'm home all weeked. please call ansd shew me. Nobody else can and I certinlty can't.
    We are talking about the same thing aren't we ? Item BISALP (second one down) from this page. That's what most people I know would associate with 'FIA' switch.

    If it isn't, then please show us what you do mean by 'FIA' switch.

    If it is, then I'll render it inactive (ie the vehicle drivable) in a few seconds with no special tools, slightly longer with a spare key. They aren't sold as a security device (though they will slow someone down who doesn't know it's there), they are sold primarily as a safety device for motorsport.
    110 V8 LPG, 90 2.5 Petrol (no longer turbo diseasel )
    See my website for info on LPG conversions

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    Apprentice mamonem's Avatar
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    Default Re: HELP - Fitting a Battery Isolation Switch

    Crikey! I've started some healthy debate here. So in summary, and to clarify some confusion that I now have

    1. Use a VWP Security Isolator Switch - Ref 60520 - as it has a proper Key, this is slightly better than the Red Keys which depend on usage I suspect, can wear at the little pin side

    2. Ensure the Battery is LOCKED and not accessible so that they can override the Key

    3. Using (1) provides no Alternator Protection, the alternative is either an FIA Switch OR a 15amp-30amp fuse ?? Not sure I'm correct here, so pls add

    4. Battery Cable?? The standard appeatrs to be 16mm (see here) , I've seen booster cables at 25mm and somebody has recommended 35mm!!! Which do I choose.

    Thanks for all the help!
    Rgds,

    Mark

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    Default Re: HELP - Fitting a Battery Isolation Switch

    Quote Originally Posted by mamonem View Post
    Crikey! I've started some healthy debate here.
    Isn't that always the case
    3. Using (1) provides no Alternator Protection, the alternative is either an FIA Switch OR a 15amp-30amp fuse ?? Not sure I'm correct here, so pls add
    Correct. The fuse needs to be big enough that it won't blow under normal circumstances, but will blow if you try to start the engine through it. If the fuse blows, then you lose your alternator protection.
    4. Battery Cable?? The standard appeatrs to be 16mm (see here) , I've seen booster cables at 25mm and somebody has recommended 35mm!!! Which do I choose.
    There is no 'correct' answer there. Ignore current ratings, they aren't relevant to the short bursty nature of start motor loads. It's a trade off between cost, weight, and voltage drop - longer or thinner cables have more volt drop, more volt drop = less performance from the starter. If the original cables (don't forget you need to consider both positive and earth) are 16mm then there's little point using 35 for the small extra you'll be adding. You'll have at least 4 foot or more of cable by the time you add it all up, so adding another 6 inch or a foot isn't going to cause any major problems. I'd probably use 25mm, and if you've any doubts (or are suffering from a 'lazy' starter) then consider replacing any 16mm cable with 25mm - I think 25mm is likely to have been standard on early models anyway (I haven't measured it).
    110 V8 LPG, 90 2.5 Petrol (no longer turbo diseasel )
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    Default Re: HELP - Fitting a Battery Isolation Switch

    Mark. My FIA switch is mounted at the front of the passenger seatbox with the switch it'self in the battery box. Not the best of places as it does interfere with the battey. It's a bit too close to the battery for my liking.

    It is not easily seen by anybody. In fact you wouldn't know it was there.

    AFAIK it can only be switched on with the key provided, spare keys are available.


    I've looked at my key today. It gets used nearly every day. It is removed every time the vehicle is parked. So it can be in and out five or more times a day. Yes even in my own drive way I remove the key. I can see no marks on the plastic key or on the metal pin after all these years of usage, I fitted the switch June 2003, I'd like to know where tis worn key bit originates from.

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    Apprentice mamonem's Avatar
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    Default Re: HELP - Fitting a Battery Isolation Switch

    I saw the wear comment on a site on google, suspect its an isolated incident.

    For the Alternator Protection ones, I'm a little concerned about the four pins and finding the right fittings for them.

    One goes to the Resistor and to earth, that's ok

    Where do I find the right connections for these:
    1. vehicle side live feed?
    2. Coil?
    3. Ignition

    Don't want to get the wrong ones, or end up not being able to find the right connections.
    Rgds,

    Mark

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    Default Re: HELP - Fitting a Battery Isolation Switch

    Quote Originally Posted by mamonem View Post
    I saw the wear comment on a site on google, suspect its an isolated incident.
    It is real, I've seen it first hand. My mates Series III was randomly cutting out on bumps, and I found out that the resistor was burned out. I figured the switch wasn't being held in far enough, thus not reliably keeping the ignition on - and found the brass pip was worn. I just pushed the brass pip out, turned it round, and refitted it. I was expecting the plastic 'ramp' to also be worn, but that wasn't the case.
    For the Alternator Protection ones, I'm a little concerned about the four pins and finding the right fittings for them.

    One goes to the Resistor and to earth, that's ok

    Where do I find the right connections for these:
    1. vehicle side live feed?
    2. Coil?
    3. Ignition
    The terminals are in pairs.

    One pair is open with the key in - those connect a load resistor between the vehicle main supply (usually Brown wire) and earth. There are many ways to connect it, but the simplest is to take a lead from the vehicle side of the main battery contacts to one terminal, and take the other terminal to the resistor and then to earth. Many years ago I was wiring one for a friend and he'd lost the resistor - so I wired to the brake lights as the nearest load to connect to (it was on the rear corner of a Mini), the brake lights flickered between pulling the key and the engine stopping.

    The other pair is closed with the key in - these must kill the engine when opened (that's the "FIA Requirement" of an "FIA Switch"). Again, there are many ways to wire this, but by far the simplest is to take two wires to the coil, pull off the coil positive (supply) wire, connect it to one wire from the switch, and connect the other wire to the coil positive terminal. On a diesel, do the same thing with the stop solenoid wire.
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    Default Re: HELP - Fitting a Battery Isolation Switch

    Quote Originally Posted by SimonHobson View Post
    If it is, then I'll render it inactive (ie the vehicle drivable) in a few seconds with no special tools, slightly longer with a spare key. They aren't sold as a security device (though they will slow someone down who doesn't know it's there), they are sold primarily as a safety device for motorsport.
    You might as well give up now Simon. Mike doesn't listen to reasonable arguments on this matter, or quite a few others come to think of it!

    Mike, please answer a question for me. If you fell off a 1000ft cliff and only suffered minor bruises and lacerations would you...

    (a) Tell everyone that falling off a 1000ft cliff is not life threatening as you've done it yourself and survived, so go right ahead and JUMP!

    or

    (b) Say "I was lucky in my case as I survived, but I wouldn't recommend jumping off a 1000ft cliff as it will most likely kill you"


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    Default Re: HELP - Fitting a Battery Isolation Switch

    Quote Originally Posted by sgl322 View Post
    You might as well give up now Simon. Mike doesn't listen to reasonable arguments on this matter, or quite a few others come to think of it!

    Mike, please answer a question for me. If you fell off a 1000ft cliff and only suffered minor bruises and lacerations would you...

    (a) Tell everyone that falling off a 1000ft cliff is not life threatening as you've done it yourself and survived, so go right ahead and JUMP!

    or

    (b) Say "I was lucky in my case as I survived, but I wouldn't recommend jumping off a 1000ft cliff as it will most likely kill you"

    When I find a battery master switch that cuts the engine as well as the battery that is better than the FIA switch I've used for these last few days without any problems I'll push that one.

    Until then as I've said I know nothing about these switches to read your comments.

    I've use FIA switches for more than a few days ...

    My Morris Minor Rally car in 1976.
    My Imp. The same switch canibalised from the Morris in 1979 and 1980' Yes it did a couple of rallies.
    Then into my Avenger then inti my Sunbeam.

    I have asked Simon to shew me how to overcome and FIA switch and shew me a worn key.
    So far he has declined.

    I find your camments out od sync with this post.

    Of course like somebody on another forum who became and "EXPERT" on overland matters you fall into the samer catagory as he does to me.

    SIMON AS IT HAD BEEN BROUGHT UP YHA I'M OUT OF ORDER SHEW ME A WORN KEY. SHEW ME HOWE TO OVER RIDE AN FIA SWITCH.
    P{OT YOUR MONEY WHERE YOUR MOUTH IS BOTH OF YOU PLEASE.

    I'm home this wekend. I have filled my Defednder up tyoday to go away next week. Sorry I can't afford to travel over to the otrher side of the country as I've spent all my months money today filling up.

    SIMON
    To save you money.
    How about meeting at Southwaite Services between 10 and 11 am Monday 5th October. I'll travel over the A66 instead of the A69,

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