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#31 florin metal works

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Posted 07 May 2017 - 10:37 PM

Save yourself all the above grief by disconnecting the battery BEFORE working on the car ( & the near £140 above)  Your electrical fault only involved one wire from alternator to battery the rest   was themal damage because the alt/battery wire tried to carry several hundred amps, therefore your fuses/alternator/starter should all be O.K



#32 Thrashed

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Posted 07 May 2017 - 10:55 PM

Save yourself all the above grief by disconnecting the battery BEFORE working on the car ( & the near £140 above)  Your electrical fault only involved one wire from alternator to battery the rest   was themal damage because the alt/battery wire tried to carry several hundred amps, therefore your fuses/alternator/starter should all be O.K


Thanks Bob. That's what I am hoping but getting them tested for free just to be sure. Defineatly a lot of thermal damage and everything seems to be ok. Just want some piece of mind

#33 Thrashed

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Posted 07 May 2017 - 11:00 PM

There are some cheap and nasty FIA master switches out there. The contacts don't stand up to constant abuse but they will take starter current for a modest, low-amp starter... but nothing too monstrous. You'll be ok because you don't have to wire it up to conform to motorsport rules, so you can run the battery live to the starter and just use the switch to isolate the feed to the alternator/main loom if you wish...
 
Make sure you wire it up properly though, using a soak resistor or the switched circuit to isolate the ignition, otherwise your car will just carry on running when you pull the switch in an emergency.
 
I won't google and link for you, you can do that yourself I'm sure ;)
 
If you want something more reliable longer-term, I would recommend one of these instead... the conventional Autolec type switch has cost me a finish on 2 rallies in the past, but the ETA has not let me down since. Well worth the money, but for road use probably overkill.... as with all these things, you makes you choice/etc ;)


Thanks Dan. Probably going to stick with a 'normal' FIA switch. It's only a road car but now thinking where is the best place to put it? Under the bonnet or on the outside so I can get at it easy without having to take the bonnet of. Not knowing anything about these is guess the key is removed when it is on allowing power through or does the key have to stay in at the time?

#34 Bob Tucker

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Posted 08 May 2017 - 12:01 AM

key stays in to run, removes when cut off. Since i had run the battery to starter cable via the switch

at first, i just connected both terminals to the same post on the new switch.


It always takes longer to put it right than do it right.


#35 stevedohc2b

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Posted 08 May 2017 - 05:08 AM

Steve please don't use only a jack axle stands a must.
If getting under any car and a good shake to check is firm first.

A jack only is for wheel off at road side only.

glad the damage is not to bad.

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#36 brumster

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Posted 08 May 2017 - 07:26 AM

Thanks Dan. Probably going to stick with a 'normal' FIA switch. It's only a road car but now thinking where is the best place to put it? Under the bonnet or on the outside so I can get at it easy without having to take the bonnet of. Not knowing anything about these is guess the key is removed when it is on allowing power through or does the key have to stay in at the time?

 

Well, it depends what you intend to use it for. I mean, I avoided stating the obvious/rubbing salt in the wound(!), but really when doing serious maintenance work, you should just disconnect the battery anyway, so if all you want to achieve is safer working on the car then save yourself some cash and just use a 13mm spanner ;)

 

But, assuming you're going this whole FIA key route for some other reason then...

1) Extra security feature : put it wherever is convenient but really, I wouldn't bother, just put a switch in something like the ECU/coil/fuel pump line. It's more covert and harder to circumvent. FIA keys aren't exactly hard to route around and I bet most thieves looking for that sort of car just carry a spare key anyway.

2) Safety (isolate car in emergency) : put it somewhere you can reach when strapped in.

3) Isolate battery because of "leaky" device somewhere draining battery : well, fix the leaky device :) but failing that, you can stick it pretty much anywhere that is convenient.

 

2 is really the only reason I can see to fit one of these to a road car, but it is rather overkill...


Edited by brumster, 08 May 2017 - 07:26 AM.


#37 Thrashed

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Posted 08 May 2017 - 08:07 AM

Hi Stephen

 

This is one area I am very paranoid about.  I jack the car up and then chock the rear wheels and I have a set of ramps that I then fit under the front wheels.

 

I learned the lesson from my uncle who got trapped for 3 hours under a lotus elan when he was younger after a jack slipped.

 

Stupid thing about this incident is that it took me longer to jack the car up than it did to check the sump bolts! 



#38 Thrashed

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Posted 08 May 2017 - 08:10 AM

Dan, really it is about option 2.  1 I have enough security, secret starting process and removable steering wheel, option 3 isn't a problem the car had.

 

Can they be wired so that off is on and on is off, so that I don't have to leave the key in?

 

If I am every doing anything major I always undo the battery, so just for emergencies really.



#39 brumster

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Posted 08 May 2017 - 09:24 AM

Can they be wired so that off is on and on is off, so that I don't have to leave the key in?

 

No. The main, high-current circuit (there are 2 large screw terminals on them) is isolated only when the key is in the off position (or removed of course) and there is no way to change this.

 

There are then 4 spade connectors on them for two further switches - one is "N/C" (normally connected) when the switch is in the on position, and the other is "N/O" (normally open) when the switch is in the on position.

 

The idea is that you use the "N/C" switch to route the live to your ignition/coil through - so that when the switch is turned off, the ignition is immediately isolated.

The "N/O" switch is used to run your alternator live* through the switch, through a large soak resistor and then to earth. This resistor is beefy enough to take a big current for a short period of time, so it drains the charge from the alternator once the battery is isolated. This may not be apparent why but it's very important - remember once running, a car relies on the alternator to provide power so isolating the battery won't do any good - the alternator will continue to provide current and your car will carry on running even with the key removed :). The soak resistor puts a brief load onto the alternator to drain enough current to cut the ignition and stop the engine... or cut the coil pack as above. I tend to do them both as a "belts and braces" type affair :)

 

* : I don't mean your alternator live solely through it; I just mean tap off the permanent live side of the switch. So you just run a small wire from the alternator-side big terminal on the switch to this spade, through the switch, through a big resistor, and then to earth.


Edited by brumster, 08 May 2017 - 09:38 AM.


#40 Thrashed

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Posted 08 May 2017 - 10:38 AM

Dan, found this diagram.  Is this how you're suggesting fitting the switch?

Attached Files


Edited by Thrashed, 08 May 2017 - 10:40 AM.


#41 brumster

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Posted 08 May 2017 - 11:35 AM

That's the puppy! You can replace "ignition coil" with coil pack or the power feed to the ECU, if the ECU supplies it directly - will effect the same thing normally.



#42 Thrashed

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Posted 08 May 2017 - 01:27 PM

Dan.  I still have a pintosaurus, so nothing fancy like ECU's for me to worry about.  I just have a box of tricks that does ignition timing.



#43 Thrashed

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Posted 08 May 2017 - 03:59 PM

Well, think I might go buy a lottery ticket as I am the luckiest person around at the moment.

 

Just had the starter and alternator back from the electricians and they are both in perfect working order!  Would never have thought they would have survived but they have.

 

Just waiting for the new wires and connectors to turn up and then I can start the chopping!

 

Thanks for all the help and support.



#44 theduck

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Posted 08 May 2017 - 04:19 PM

Brilliant news!



#45 brumster

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Posted 08 May 2017 - 04:19 PM

You think about it, electricity tries to find the quickest/easiest way to earth... it sounds like you grounded the chassis to the permanent live on the alternator. So current flowed from the battery down the power wire to the alternator terminal, then straight down your engine mount or whatever. The heat from the melting wired obviously started to meld all of the surrounding wires into one another but - here's the thing - unless any of them offered a "better" route to ground (ie. lower resistance) then it's highly unlikely that any significant current went down them - and potentially through anything of value, doing damage. Stuff like ECUs - including your fancy ignition module thing - should generally have short circuit/reverse polarity protection in them; it would be pretty shoddy of the manufacturer to not include stuff like this. So... yeah... just offering some comfort, you may not be too bad with this.