Battery isolator switch with ignition cut-off.

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Ruari

Ruari

Active Member
Posts
281
Location
North Ayrshire
I have no idea where to post this on the forum, but hey ho...

Does anyone have a wiring diagram for the Battery isolator switch with ignition cut-off. As approved by the FIA.
A tried to google it but all I get is it should come with the swith - well I'm rewiring the whole vehicle and found alot of dodgy connections and trust NOTHING allready in it.
 
just wired mine up fully. I have run a bulb with the resistor as sometimes the resistor fails leaving you with a chance of knackering an alternator. if the bulb does not light and engine die then go off you need to check that the resistorbulb is connected might save the alt.
 
For competition peace of mind a flick of the switch does three operations.

The problem is the ignition feed on our motors comes from the starter main live. This is fed permenantly by the alternator when the engine is running. isolating the battery will allow the engine to run on the power it produces from the alternator. so but putting the ign through the kill switch the feed from the perm fed live point on the starter is interrupted and engine shut down.

Flick of the switch does:

1 Isolates the main battery,
2 Turns off the Ignition,
3 allows any current being produced by the alternator to go to ground via the resistor (my case resistor and light) this is to stop any current being left with nowhere to go but back through the alternator.

Things to watch out for are: FIA switch is only rated at 100A Continious. so forget putting even the smallest winch through it. you need a seperate switch which is ok but for comp use you need a single operation kill switch that kills everything in 1 operation.

This means you need linkage to both switches so one operation turn both off together or some put a swing bar on it so the swing bar operated both switches.
 
I have two switches on both my 90 road motor and my lil 80 inch. The 80 I need to link both switches together via ball joints and rods so the kill switch cables will kill everything.
 
For comp use they scruteneers like to see it as close to the battery i.e short as possible main batt lead as possible as that remains the only live wire when the cut off switch is switched.

cut off switch handy when your hanging from your harnesses upsidedown
 
DISCOVERY1-DAZ said:
I can see the benefits from having 1 fitted if you do competitions and trials.

Daz
Click to expand...

I have fitted one to each of my LR's for over 25-years, even those not involved in competion (including my wife's MGB). They are a very good idea on any vehicle for both a safety & security.
Items such as alarms and an interior light can be rigged up through a low ampage fuse so you don't have to do without electronic security or light which is a real issue on these dark evenings.
The key (a big red thing) is on a karabiner which attaches to my normal keyring so it is never separated from the normal keys when not in position.
 
Cheers chaps.
I was thinking of running a 2nd battery which would only do the winch. I was then going to use a smart split charger to charger either battery bank. The smart charger is connected direct to each battery with the alt. charge going into the middle terminal. Thus it misses out the isolator and as I see it when you shut off the battery, any excess volt / current wil go into the battery. This should be ok shouldn't it?
 
What I didn't realise is the isolator has:
Main contacts normally open
pair of spade ternminals normally open
pair of spade terminals normally closed.

Open terminals are feed from battery to the whole car
Open spades feed the coil pack & my fuel pump.
Closed terminals are to discharge any feed from the alternator to prevent damage to its diode pack. i.e stop it getting knackered
 
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