19 replies to this topic

[minisilverbullet]

It's probably been damaged by overloading. It should be well within spec running just one element, try a new one and see if it works.

Just tried a 40a relay, and get the same issue.

[Dan]

Running one element and it's buzzing? Where is the relay coil earthed to and is it reliable? Is it a diode or resistor protected relay?

[minisilverbullet]

Got this sorted! Thanks for sticking with me Dan! 

 

The car had been sitting a while in the garage, and I do remember it struggled to start. I googled "buzzing relay" and found that one cause is the voltage was below the latch voltage of the relay from google: "The relay will start to buzz when the magnetic field the coil generates get so weak that it's barely enough to overcome the return spring on the contact arm (this is all inside the relay).". the voltage was just below 9.5v. 

 

​Anyway I put the battery on charge. In the meantime i wired a new feed wire from the solenoid to the relay using 84/03 6mm wire good for 42 amps (previously i used 3mm wire, which prob wasn't up to the job for both circuits ,but as said before it buzzed even with one circuit connected). 

 

Earthed the relay using 3mm wire (rating 27.5 amps) and then used the same 3mm wire to each side of the windscreen. I have ran both these sides to the same pin on the relay. I this ok? The relay is a 40a and fused. 

 

​I earthed the windscreen using 3mm wire from the centre wire.

 

Does all this sound alright? 

 

​Anyway took the battery off charge and tested the wiring and it is fine. doesn't buzz etc. I guess this was the battery being low? or maybe it was the new 6mm wire i added. 

[Dan]

It was probably a combination of both, the high load of the elements in parallel would have really hammered the battery. I assumed you'd be testing this with the engine running I'm afraid so I'm sorry I didn't mention it, you will kill the battery really fast with that thing running and the engine off though! The elements in series didn't make it buzz remember.

Remember if you've done it that way the earth at the centre is carrying the load of both elements, it still sees the full 34A. Other than that it sounds fine. Relays tend to be short lived near their rated capacity, personally I'd probably run it on a separate 30A for each side but if you've already done it then leave it (apart from the common earth) as it's safe and will work. You just might have to replace the relay frequently. There is a website that sells really high quality relays that bear their rated load well but I can't remember what it is.

[minisilverbullet]

I will replace the earth wire with the 6mm wire then.

I could of bought a 50a relay, I guess I should have, I watch the relay carefully.


Thanks again.