Warm relays

[nathanlee]

I didn't want some of the bigger pulls (anything above 5amp) running directly through my cheap-o switch panel, so I've ran the potentially larger draws through separately fused automative relays. Now, I've not really been pulling much current through them but they're warm.

One is running the 12v LED driver and has been running well under an amp.

The other has been left on accidentally, but shouldn't be using anything as it's on the autopilot circuit which is currently open as no AP plugged in.

Is this normal? Seems like a giant waste of power to me.

 

[nigelmercier]

A 12V relay will be about 100Ω, so will consume about 1.5W.

 

[nathanlee]

A 12V relay will be about 100Ω, so will consume about 1.5W.

Well there's an example of "a little knowledge..."

There's me thinking I was being sensible by not trying to ram 10amp+ through the switch panel when everything is switched on. I think I might have to return to the drawing board on that idea. I didn't bother to check, just presumed the current used to power a relay would be entirely minimal. D'oh!

 

[nigelmercier]

I think it is minimal, it's only about 0.1A. It's only when you consider the wattage that you realise that there will be some heat, about the same as an indicator lamp.