I want to fit yellow halogen bulbs and I believe that I will need to fit a relay to protect the switch from damage. As Manuel used to say in Fawlty Towers - "I know nothing!" so...

What is a relay?

How are they rated or are they all the same?

Where can I buy them?

Where do you put them?

Diagrams, or detailed instructions suitable for the hard of wiring are welcome.

its a 'lectric switch

they are rated by the ammount of current they can handle....15A is what you want 2 of em

motor factors maplins and the like

in yer pocket, then bedside cabinet before the other 'alf makes you move em
(bulkhead is usually most convenient)

but the relay is only half the story you need as fuse as well, you can get relays with built in fuses(fused relay)

wire comes from switch and goes to switching ternminal on the relay, then to earth

from the battery 12 v goes to the fused relay or goes to relay via fuse, then from the relay to the existing wire to the lamp.

there is enough spare wire in the system when you disable the dim dip fiasco to do the whole thing, youll also need 8 or more insulated female lucar crimps to do the job


so when its all done the switch only handles a tiny current that throws the switch in the relay and turns on the 10a or whatever the lamps draw

you need one for dipped and one for main

sean

Old-Nail,
to back up the advice Sean's already given, this site has got plenty of detail, including figuring out how to identify the various terminals on the relays.

< http://freespace.virgin.net/tommy.sandham/relays.htm >

It's worth noting the comments about crimped connections vs soldered and if you haven't got a soldering iron, I'm sure that I noticed some in Aldi earlier this week.

The section describing how rapidly the efficiency of a bulb drops with lowered supply voltage is quite an eye opener...

ken

Thanks fella's. I'll give it a go sometime soon. If I fit the halogens without relays for the time being am I risking armageddon or no?

Possibly, possibly not. Does the switch get warm currently?

I'd make one small change to the wiring diagram at the end of the link Ken posted...



I'd put the fuse between battery & relay, not t'other side. As for the fuses, a normal spade terminal fits perfectly onto the leg of a modern-style blade fuse.

Ta very much. I'll have to sit down and study those instructions in the hope they might sink in.

Adrian,
if you're suggesting using only one fuse feeding both relays and that fuse blows, that's a 'Oh look, no headlamps, where did the road go?' sort of moment.

With the original setup, if one circuit goes down, you can still switch to the other...

ken

Not necessarily... Still one dip fuse, one beam fuse - just before the relays instead of after. I'd rather have as many of my badly bodged connections fused as possible - so the fuse goes as near the battery as possible.

So these relays, might I already have some in the form of those used on the now defunct dim dip set up? Are those what I need? if so I do have a couple doing nothing, then I just need to figure out where to wire them in as my wiring loom isn't as standard.

no armageddon

and the relays for dim dip are switch over relays rather than on or off, can be done but sticking in these
make life easier and the fuse protects everything tho id put in a blue 15a fuse

Sean