JoelP
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| posted on 26/5/04 at 05:10 PM |
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fuses and foglights
hello all. nearly finished on the wiring, just two more small problems.
number one, i just got the headlights working, with a 10A fuse for dips and another 10A fuse for mains. They both popped on the first test. Using 20A
fuses, all is now well. But i was just wondering if it was expected for a pair of 55/60w bulbs to break 10A fuses: P=VA so 120w=13xA, which must be
around 9 amps drawn. Should 9 amps be able to bust a 10A fuse? i appreciate its a close one. EDIT: just thought, if the battery was a bit flat the
current would've been closer to 10 anyway.
T'other problem is the fog lights. Am i right in thinking that these can only operate on dip or main beam, but not on sides only? the way i had
it initially was working ok off the side light relay but that obviously isnt how its meant to be, but since i have seperate dip and main relays that
would involve diodes to link both to the fog relay. (i am using standard sierra switch gear where the two relays are operated by the switch earthing
either of bn/y and bn/w for each. would have had a diode up to each wire, so that the fog relay could earth thru them but without cross linking them)
im now trying to use the earth from the top of the light switch to do the relay, using its 'double-throwness' to keep it sperate. with
this set up i would have two relays in series (fog and dip/main) hence each would only get 6Vs.
So this bring me to my question: Would this still be enough to close the relay, or is the full 12V needed? apparently its around 150mA to close them,
though i dont know if this is relevant here.
failing that, is there an easy way to get the fogs switched without having the original dimdip relay?
thanks for bothering to read this far, much appreciated.
[Edited on 26/5/04 by JoelP]
Beware! Bourettes is binfectious.
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stephen_gusterson
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| posted on 26/5/04 at 06:27 PM |
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relays usually need about 70 - 80% of rated voltage before they will pull in, and will release about 50% of rated voltage.
There was debate on here before about fogs only being on when headlights are on, but my understanding - that i have seen on my cars - is that they
should only be on if the mains or dips are on.
I dont quite understand why you are trying what you suggest with the relays.
In my setup, I used the original granada light switch. This has two positions (not inc off).
First position supplies sidelamps front and rear, and the dash board lamps. The second position does same, but also provides a feed to the headlights.
I cant remember quite how the dip switch is wired - think its switching to ground? Whatever - there are two relays which are switched via the feed
from the dip switch.
In this case, just connect a FURTHER relay to the feed to the dip switch. Put the contacts of that relay in the feed to the fog lamp, via the lamps
own fog switch.
If you put the fuses for the headlights in the feed FROM the dip switch, it doesnt draw current for the rear lamp thro their fuses.
In this way, if you dont have the main lights on, you dont get a fog lamp on. (common power to beams relays also turns on fog lamp power isolation
relay)
Another simpler way is to use a big f^&k off switch for the lights, and take the feed directly from the light switch beams position.
In my design, the light switch only powers relays to the main lights, and the fog relay.
As far as your lights blowing a 10a fuse, that shouldnt happen.
Fuses are not precision devices. I dont know the actual rating for a car fuse, but as an example, you can expect a typical fuse to run for an hr or so
at several 10's of percent over rating before it goes. Its big surge loads during shorts that makes em pop right away
atb
steve
ps - if this reads crap, let me know and I will draw you a sketch
[Edited on 26/5/04 by stephen_gusterson]
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JoelP
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| posted on 26/5/04 at 06:56 PM |
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quote:
Originally posted by stephen_gusterson
First position supplies sidelamps front and rear, and the dash board lamps. The second position does same, but also provides a feed to the headlights.
I cant remember quite how the dip switch is wired - think its switching to ground? Whatever - there are two relays which are switched via the feed
from the dip switch.
on the sierra system, the first click of the light switch send power down a grey wire to light up the side lights and other related lights. The second
click connects up an earth from the other side of the column. This earth is where the dip and full beam relays come thru, and it is the dip switch
that selects which one is on. There is also another perminant earth to allow the main beam to be flashed on.
since these two wires have already come thru a relay (one from the dip relay and one from the main beam relay) if i put another here it will be in
series and only 6V.
quote:
In this case, just connect a FURTHER relay to the feed to the dip switch. Put the contacts of that relay in the feed to the fog lamp, via the lamps
own fog switch.
wouldnt the fog light still not work on main beam, if it was activated by the dip beam feed? perhaps this is why i should've used more of the
original circuitry... off for a look in the book of lies.
Beware! Bourettes is binfectious.
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Peteff
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| posted on 26/5/04 at 07:00 PM |
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Just take a feed from your dip relay to the switch for your rear hazard. That will satisfy the SVA requirement and it's simple. It doesn't
have to work on main.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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JoelP
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| posted on 26/5/04 at 07:01 PM |
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sussed it steve, cheers! earth the fog switch after the dimdip switch and before the light switch. Offsky to do it now!
Beware! Bourettes is binfectious.
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David Jenkins
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| posted on 26/5/04 at 07:07 PM |
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Fuses blowing:
When a filament bulb is cold it has a fairly low resistance - it's only when it gets hot that it has its 'proper' resistance. So,
when you apply the current to a cold bulb it will be taking a fair bit more current for a fraction of a second.
You have 2 alternatives - use a bigger fuse, as you have done, or struggle to find 'slow-blow' fuses that will take the initial surge.
The first option is easier, and is the normal approach. A 20A fuse is fine for protection of headlamp circuits (it's what I've got).
rgds,
David
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JoelP
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| posted on 26/5/04 at 07:27 PM |
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Cheers david. I read petes post too late! i've made it work just fine on both dip and main beam. I suppose its logical that the fog light
needn't work on full beam as you dont use it in fog anyway! But sod it, its a technical excercise and i beat the bugger!
thats it folks, all the wiring finished except number plate lights and dash lights, and of course the warning lights. Piece of wee really
funny thing though, months ago i made a list of 15 things i needed to do to finish the car, now ive done most of them i somehow have a list of 20
things to do. neverending tasks...
Beware! Bourettes is binfectious.
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givemethebighammer
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| posted on 26/5/04 at 09:55 PM |
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quote:
Originally posted by JoelP
T'other problem is the fog lights. Am i right in thinking that these can only operate on dip or main beam, but not on sides only?
can't find any info on this SVA reg anyone got the original details ?
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James
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| posted on 27/5/04 at 09:57 AM |
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Joel,
So then Joel, how do you fancy a trip to Guildford to wire mine up!
Failing that- if you could just post a link to where you've done your step-by-step online guide to wiring a Pinto'd Locost I'll just
follow that! 
Well done!
James
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JoelP
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| posted on 27/5/04 at 04:02 PM |
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id love to come down james, but id probably die of old age before i got there! tis a long way down there...
really is easier than it sounds, doing the wiring. Have you got that link/attachment i posted ages ago? by a guy called phil bradshaw, it sums up
everything relevant. shout if you havent got it.
Beware! Bourettes is binfectious.
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James
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| posted on 28/5/04 at 10:28 AM |
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Shout!
James
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JoelP
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| posted on 28/5/04 at 12:25 PM |
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hope this works...
http://www.locostbuilders.co.uk/viewthread.php?action=attachment&tid=8749&pid=67352
ignore the attachment, its buggered...
[Edited on 28/5/04 by JoelP]
Beware! Bourettes is binfectious.
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