myothercarsa2cv Posted July 25, 2013 Share Posted July 25, 2013 Getting bored of disconnecting the battery and reconnecting it every time I use the car, and now little brother is insured on the car (yikes) I'd like to fit a switch under the bonnet to isolate the battery and save it from draining. Little brother will probably kill himself if he touches anything electrical so a switch should make things a little safer. Thinking of bunging one of these in line with the positive terminal - will that completely isolate the battery and stop any kind of drain? Is there any possibility that the switch will throw and fry everything? How should I mount it? I don't think the cables will stretch to the bulkhead, so it will have to go by the battery. Advice very much appreciated! Link to comment Share on other sites More sharing options...
Leadership Team SLR No.77 Posted July 25, 2013 Leadership Team Share Posted July 25, 2013 Why not just fit an FIA cut-off switch ..... Link to comment Share on other sites More sharing options...
Roger Ford Posted July 25, 2013 Share Posted July 25, 2013 Why don't you want to fit a proper FIA switch? Cost? Were you intending to chop the existing lead and fit new terminals? It's very much NOT easy to fit terminals to main battery leads. So it would seem that you're better connecting your existing battery lead to this and running a new lead to the battery. Which means it could mount in the bulkhead. Except that if you have a Banner or similar, your battery lead probably has a 6mm ring connector on it, and the switch will need 8mm or maybe 10mm (or imperial equivalents). So it's not an easy job. And you'll also need to remember not to use it when the engine is running as it doesn't have the "dump resistor" that a proper FIA switch has. Link to comment Share on other sites More sharing options...
7ERRY Posted July 25, 2013 Share Posted July 25, 2013 John call me i have a fia switch 😬 Link to comment Share on other sites More sharing options...
AntR Posted July 25, 2013 Share Posted July 25, 2013 I use one of these: http://www.amazon.co.uk/Battery-Cut-Off-Switch-Universal/dp/B007C7CJT4/ref=sr_1_1?ie=UTF8&qid=1374761259&sr=8-1&keywords=car+battery+cut+off+switch Connect to negative terminal and it stops battery drain - quick and easy! Link to comment Share on other sites More sharing options...
Area Representative Golf Juliet Tango Posted July 25, 2013 Area Representative Share Posted July 25, 2013 I would fit an FIA switch. Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted July 25, 2013 Share Posted July 25, 2013 John ..... I have a taper drill bit that will make a big enough hole for the switch. Fitted mine in the bulkhead above passenger knees. Out of sight but easily accessible to the driver. Now home every day if you need a hand ! Link to comment Share on other sites More sharing options...
myothercarsa2cv Posted July 25, 2013 Author Share Posted July 25, 2013 Thanks all. Ian, do you have the FIA switch as well? I have a tapered drill bit somewhere... I'll let you know if I can't find it. Of course you're welcome to help fit it anyway No reason not to go for the FIA switch (you can get them reasonably cheaply), but I know that I or my brother will lose the key at some point! I also get the impression they fail a lot. Whatever I use, I want to keep the extra wiring to a minimum - I've currently got the intercom and cigarette lighter wired directly on to the battery (I'm not perfect!) as well as the starter lead and brown wires, so want to keep the need to extend these to a minimum. I don't compete, so no need for anything more fancy than something to break the circuit. AntR, I think that would worry me as I have a full metal cage holding the battery down, wouldn't want it fouling! Link to comment Share on other sites More sharing options...
makingff Posted July 25, 2013 Share Posted July 25, 2013 Quoting myothercarsa2cv: AntR, I think that would worry me as I have a full metal cage holding the battery down, wouldn't want it fouling! #potentialstupidquestionalert# Why would having a battery cage make a difference? It's the negative feed so earthed anyway? Looks like a good solution to me! Simon Link to comment Share on other sites More sharing options...
tbird Posted July 25, 2013 Share Posted July 25, 2013 John if you don't mind going under bonnet to isolate, These work quite well and are cheap and cheerful, had one on last Audi as it had a battery drain I could not find. Don't fit the fused link if you want to totally isolate. *redface* Sorry AntR read post butdidn't follow link 😔 Tim Edited by - tbird on 25 Jul 2013 21:27:58 Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted July 25, 2013 Member Share Posted July 25, 2013 How are you connecting and disconnecting the battery at the moment, and does it live near a mains socket? Jonathan Link to comment Share on other sites More sharing options...
myothercarsa2cv Posted July 25, 2013 Author Share Posted July 25, 2013 JK - I just remove both leads and pop the battery to one side. Sometimes its near a plug, sometimes it isn't I thought about investing in a conditioner, and I might still do that, but for those times where no plug is around, I probably need the switch. makingff, not stupid at all. I didn't read AntR's post I was thinking it should attach to the positive, hence the fear of shorting on the cage. Happy to go under the bonnet, it's not exactly a chore on a 7 😬 P.S. How did everyone extend the wiring? Cut and solder? Replace with longer lengths? Crimps? Edited by - myothercarsa2cv on 25 Jul 2013 22:51:22 Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted July 26, 2013 Member Share Posted July 26, 2013 You've probably considered this already, but would a conditioning charger and a socket under the dash address your needs? Jonathan Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted July 26, 2013 Share Posted July 26, 2013 Missed your earlier question ...... I have a very very cheap switch with two keys from CBS online. Any decent car spares shop will make up new fat cables with suitable eyelet connectors for you. Link to comment Share on other sites More sharing options...
Ian B Posted July 26, 2013 Share Posted July 26, 2013 John, if you fit the simple (non- FIA approved) switch the Ian suggests, in the negative feed from the battery, there will be less wires to extend. Fitting it in the position Ian has (when he copied mine ) will probably mean you only need to get one negative lead made up from an auto-electrical place with a lug on each end Link to comment Share on other sites More sharing options...
myothercarsa2cv Posted July 26, 2013 Author Share Posted July 26, 2013 Thanks all and thanks Simon for the email. There is the obvious danger of using the key when the engine is running if I fit it in the negative lead, and I don't intend to use it for that, but what if the switch fails? There is lots in the archives about switches breaking... And does just disconnecting the negative completely isolate the battery? JK - a conditioner is unfortunately no good when I'm not near a plug socket, so I'll need a switch anyway. Link to comment Share on other sites More sharing options...
Leadership Team SLR No.77 Posted July 26, 2013 Leadership Team Share Posted July 26, 2013 Quoting myothercarsa2cv: There is lots in the archives about switches breaking... I've had 2 Sevens, both have had FIA switches fitted from new. The first I sold at 10 years old and it was still on the original switch, my current car is 14 years old and is still on the original switch .... there's 2 sides to every story Stu. Link to comment Share on other sites More sharing options...
Roger Ford Posted July 26, 2013 Share Posted July 26, 2013 Quoting myothercarsa2cv: There is lots in the archives about switches breaking... I'm not convinced it's that common. I've never known one fail in any of our race cars. Perhaps it happens when they're not used very often. And does just disconnecting the negative completely isolate the battery? It does if it's the only thing connected to the negative. If you've anything else wired directly to the negative (intercom, cig lighter socket) then you'll need to make sure you haven't inadvertently "double-earthed" them. Easy to check with a multimeter - check there's no continuity between the chassis and the negative terminal when the main lead is disconnected. Link to comment Share on other sites More sharing options...
CharlesElliott Posted July 26, 2013 Share Posted July 26, 2013 Just attach the FIA switch to the eyebrow over it. Link to comment Share on other sites More sharing options...
SUPERLIGHT91 Posted July 26, 2013 Share Posted July 26, 2013 FIA switch is the best idea - I had a lesser non-FIA copy on my 911. To cut a long story shot the switch failed, and caused me no end of diagnostics problems. moral of the story is - fit the best you can to start with when it comes to electrical, and take time fitting it as professionally as possible to save you headaches in future. good luck. Link to comment Share on other sites More sharing options...
mattmurdock Posted July 26, 2013 Share Posted July 26, 2013 Another vote for the FIA switch - I have two keys, so one is always left somewhere safe in the garage in case I manage to lose the one I have with me :). Link to comment Share on other sites More sharing options...
MartinH Posted July 26, 2013 Share Posted July 26, 2013 I fitted an FIA switch from CC over the winter. To do it properly involves more wiring and soldering than you'd think and also a bit of hacksawing of brackets out of the way (on my SV) but its a satisfying job once its done. I was also worried about loosing the switch key if I was out (or some scrote nicking it) so I have a spare hidden inside the car somewhere that I can get to if required while I am out. Also be aware that the switch sets from CC seem to have a different spec key to the rest of the world (i.e. all the spares you can get at auto jumbles and Stoneleigh etc. I bought a spare from Stoneleigh but had to shave down the diameter in order for it to fit in my hole Link to comment Share on other sites More sharing options...
SUPERLIGHT91 Posted July 27, 2013 Share Posted July 27, 2013 For all you reading this with experience of fitting these. I noticed this morning my brother's car has an under-dash non FIA (but similar style) isolator switch which is: a) bulk head fitted b) fitted in line with the negative lead (as opposed to the positive) He only uses it to isolate the battery in winter, but I'm wondering if this would cause any power issues or concerned running in line. As it happens he is suffering the K-click after every drive, and I'm wondering if this isolator's switch in-line is contributing in anyway to a resistance problem? Speaking of resistors, I recall the Caterham FIA switch used to come with a resistor to connect to the body in some way. What purpose does this serve on an isolator connected in the correct way (ie to the positive battery terminal)? Thanks Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted July 27, 2013 Member Share Posted July 27, 2013 Resistance isn't futile Jonathan Link to comment Share on other sites More sharing options...
MartinH Posted July 27, 2013 Share Posted July 27, 2013 Wiring and resistor explained in the 7 FAQ Link to comment Share on other sites More sharing options...
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