Headlight switch getting HOT

[msggunny]

With the lights on the switch is getting rather hot, as is the hot wire coming into the switch.

Im running the Hella conversion too.

Any ideas? Do i need to run a relay(s), if so where should i put it in relation to the switch or lights? (closer to the switch or closer to the lights)

Thanks.

Richard

[SafeAirOne]

It's often the sign of a corroded connection where all those electrons are squeezing through the last little bit of metal that is still making good contact, especially on a high-amp circuit like the headlights. Also the sign of a short in the system, overloading the wiring.

My bet is with the bad or dirty contacts/connection.

[Nium]

P=IE

What Hella conversion on what Rover?

The formula for power (watts) is...

Power (watts) = I (amps) x E (volts)

If your wire and switch are getting hot then you are probably drawing to many amps thru the switch and wire; barring corrosion causing excessive resistance. Any company is going to use the minimum size wire for the stock assembly and I'm sure Rover is no different. I looked at the Hella lights on RN and all seemed to be in the 55W range with the Stage 1 being 60W and that's per bulb. So a pair of bulbs would be 110W which at 12V works out to be 9.17A. That's a fair amount of juice. On high beam for the Stage 1 that'd be 120W (a pair) at 12V that's 10A. 14 AWG wire should be good for up to 15A and 12 AWG for 20A. I believe I've read somewhere the switches are designed to handle 10A. I tried finding the stats on the stock lamps but only found that their 12V, not very helpful.

A relay would be a good idea 'cause then your switch would only handle the amps to sustain the relay and the relay would handle the juice for the headlights. Just make sure to get one that will handle the power your looking to put thru it. Doesn't matter which it's closer to, switch or lights, just as long as it's accessible and in an area where heat dissipation isn't an issue. Keep the length of wire as short as possible to reduce the natural resistance in the wire.

Before all that double check your connections and grounds to make sure they aren't corroded like SafeAirOne pointed out. On older switches you can take them apart to check for corrosion and apply a little dielectric compound to help cut down on resistance.

Cheers!

[amcordo]

Relay

A relay is always a VERY good idea for something that uses a lot of power (like the headlights, or an electric radiator fan). The goal on a high power connection should always be to shorten the length of wire that's carrying the energy. If you've got less wire then there's less room for a serious problem like a short to occur.

The rover is one of the easiest vehicles to run wire on - consider placing a relay (either a water-resistant one, or a relay encased in a weather box) in the engine bay near the lights. You'll be safer for it!

[jb_]

A relay is always a VERY good idea for something that uses a lot of power (like the headlights, or an electric radiator fan)

IMO there are two choices: a relay or a fire.

[SafeAirOne]

Missed the bit about the Hella conversion, which is presumably the 60w/55w hedlamp upgrade. I'd agree-Get a relay or a fire extingisher.

I'm surprised that a relay isn't part of the kit like it is for the offroad lights, which also use 55w bulbs.

[SafeAirOne]

Trying to find a reference on TeriAnn's website for another post, I came across this info that applies here: http://www.expeditionlandrover.info/halogenLamp.htm

[msggunny]

Great! Thanks for the info, i am pretty sure i need to clean/replace the switch and do the relay upgrade.

More stuff on the "to do" list, thankfully i dont drive her at night often and i have a fire extinguisher too!

[NickDawson]

A relay is always a VERY good idea for something that uses a lot of power (like the headlights, or an electric radiator fan).

I second the relay approach - the relay on my electric fan went out and I wired it straight through the switch, it also got pretty warm (12 gauge wire BTW).

When I looked at the hela kit, RN suggested the relay solution. I've been eyeing that kit myself and am curious to hear more about how you wired it and how they are working out

[kevkon]

The best route imho if you are adding electric loads to your rover is to get a modern fuse block. These usually have relay ports as well as the more modern fuses. You can get these new from Painless or used from a salvage yard/ EBay. Gives you plenty of room for expansion so you don't end up with a wiring mess and relays all over the firewall.

[Nium]

Wire Ampacity

Just a clarifier 14 AWG wire is good for 15A but for auto applications no more than 80% of that should be drawn so 14 AWG shouldn't have more than 12A and 12 AWG at 80% of 20A would be 16A.

Shocking!