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Battery Cut-Off Switch


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#1 Pavel

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Posted 25 January 2005 - 10:47 PM

Any ideas how much these things normally can take (current wise)? I'm looking for an ignition switch and if all my electrics that come on with ignition are switched on im looking at around 60 amps if not more, and I have yet to come across a flippy switch and/or regular relay that can handle that much...

Any ideas what I should do? 2 relays in parallel would work but only if the electrics arent switched on when turning on ignition, since the 2 relays wont switch on at the EXACT same moment, which will probably burn one of them out if done several times.

#2 Dan

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Posted 25 January 2005 - 11:01 PM

You can get high current relays. 70A or 180A. They are just the same, but the load terminals are bigger so you can't put them in a standard socket. I use Vehicle Wiring Products. Linky Link!

#3 Wil_h

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Posted 27 January 2005 - 01:08 PM

A standard isolator switch (Deamon Tweeks MW002) is rated at 100 amp continuous. And I guess will take plenty more than that for starting.

60 Amps though, that's a lot, have you got a big stereo?

My car only takes 2.5 Amps to run. and a max of 14.5 Amps with all the lights on and the rear heater and fan on.

I guess you will be using a better alternator and bigger battery.

Wil

#4 Pavel

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Posted 27 January 2005 - 05:55 PM

Only the coil takes 9 amps :thumbsup:
Lights, 4 fog lights, 2 rear fog lights, and a bunch of other things.

Anyway I may have solved my problems by using a starter solenoid form a metro lol :] Should do the job!

#5 Dan

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Posted 27 January 2005 - 05:57 PM

How do you manage that Will? Even the just rear screen, fan and two sealed beam lamps on dip will draw more juice than that and that ignores the sidelights, tail lights, dash lamps, ignition, stereo, instruments.......

#6 Wil_h

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Posted 28 January 2005 - 09:30 AM

Well that's what I measured coming out of the alternator. and measuring voltage and corrent levels is my job.

I only measured the 'thick' brown wire, but I think the other are a supply to the alternator/ warning light and the other is the earth. I'll check the diagram later.

The coil can no way take 9 amps.

I reckon 15 Amps seem about right, maybe 20 at a push.

I'll have a think about what I measured and get back to you.

Wil

#7 bluebottle

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Posted 28 January 2005 - 11:46 AM

Only the coil takes 9 amps :lol:
Lights, 4 fog lights, 2 rear fog lights, and a bunch of other things.

Anyway I may have solved my problems by using a starter solenoid form a metro lol :] Should do the job!

you must get a hell of a lot of pea soupers in cyprus to need all those fog lights!

#8 Pavel

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Posted 28 January 2005 - 11:59 AM

Front fog lights for trips to beach house at night (2-3 cars on the road, no lights), approx 50 mile trip. Rears are because there's some right arses that tailgate A LOT.

#9 Dan

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Posted 28 January 2005 - 12:10 PM

Both the heavy gauge brown wires from the alternator are supply, the earth is the engine block!

You've only measured 1/2 of the load! :saywhat:

5 amps for ignition and 30 amps with the lights on is a lot more believeable.

And yes the coil does draw a peak of about 9 to 12 amps when sparking, but it's intermittent remember so it averages out to about 4 or 5. Takes a lot of juice to provide 30,000 volts you know.

#10 Pavel

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Posted 28 January 2005 - 12:14 PM

Dan youre the pro sparky! Is there anything wrong with using a starter solenoid as my ignition relay?

#11 Dan

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Posted 28 January 2005 - 12:26 PM

Yes, starter solenoids are not designed for continuous duty. It'll overheat the coil in the solenoid and start smoking after about 10 minutes! :saywhat:

You need a relay I'm afraid, or use a kill switch if you want to do it manually. But those FIA kill switches are a pile of junk. They are elctrically up to it, but not physically. They aren't designed to be used as an ignition switch and they do break fairly quickly with regular use.

#12 bluebottle

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Posted 28 January 2005 - 06:14 PM

i'd agree with dan on the FIA kill switches not being up to regular use!.......i had one fitted to my car when it was rewired, and now to get it to work i have to wiggle the key to get power!




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