Heated Windscreen

If your screen has only two lugs/connections, then one of them will be earthed to the body somewhere, so only one relay is needed. If the cable is warm, it is a sure sign it is undersized. Also, warm connections imply poor contacts. Having said all that my old H plate RRC never demisted/defrosted/ deiced itself anything like as quick as the work's 1st generation Modeo. That was brilliant, the RRC by comparison was a load of c**p.

Gordon

A relay could be said to have these basic functions.

To allow the switch to be fitted near anywhere without the penalty of voltage drop due to the power circuit being as short as possible.

They allow a power circuit to be shared.

The switch doesn't have to carry the same high current as the device it feeds.

If you are fitting a new dedicated power circuit between battery and screen it makes no difference where the relay goes along that circuit.

PS. Remember and fit a suitable fuse as close to the battery as possible.

Sorry, i meant 2 +ve and a -ve in the middle.

A fuse will be fitted. Dont know what size though, as i dnt actually know how much it will pull

ISTR that the heated screen pulls something like 40amps ....

There will be one in the original installation - or a circuit breaker - so that will give clue?

Warm cable or terminals is not good. Means that the energy is being dissipated in the wrong place.

Not sure I follow what you actually have. A DII's heated screen is split left and right with each half being fused at 45A. I think you really need to find out what the load is then see what relays you can find to switch that load. Personally I think one for each feed would be best, assuming that there are two feeds not one and an earth return.

Not particulary relevant except you could feed both relays with one short and really big wire if in near the battery. Don't forget protection (fuses).

Is this heated screen a non-standard add-on? If not I'd expect to find the wiring, protection and relay(s) (or places for 'em) already there?

In news: snipped-for-privacy@mid.individual.net, Mark Solesbury wibbled :

Should make absolutely no difference, what will affect it is thin cables and/or a lousy earth connection. My money's on the latter.

Thats the 1st cable i will replace, with the original setup.

:)

Its got 2 +ve's and one -ve in the middle

Yeah, it has been retro fitted to my 90

Before applying the shotgun approach - why not check that the original cable is up to the job or not? You'll find cable ratings and descriptions here.

My money says the original installation is fine and you have a faulty connection somewhere.

In that case I'd go for 2 relays one in each feed (finding a 90A relay might be troublesome, indeed 45A might be interesting). Also check that the centre ground is well made and a short a lenght as possible to the vehicle chassis.

So you didn't put man enough cable in the first time around. B-)

Can you get at the earth terminal on the screen easily(ish) if so try a jumper straight off the battery.

Not by me - by the bell end that had it before me... Ive found more wires joined together with black tape than id like !!!

At least this is only 12v, though currents and thus I^2R losses are higher but I've found mains wires twisted together stuffed into a red plastic wall plug and wrapped in tape...

I didn't know there was such a thing - not on a Landy anyway ! But have just googled it and found this article on fitting one.

Steve