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oldtuckunder

Chattering relay

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Hi electric guru's got an odd problem and wondered if anyone had experienced similar.

Just wired up an auxiliary fan switch in friends car,  it has an electric fan via a relay and inline thermostat. I have taken a spare power supply to a new relay, taken the feed to 85 and then an earth via a switch on 86, piggy backed the supply to 30 and taken the feed to the fan off 75. When you turn on the switch the relay chatters for a second or two as the fan starts and then shuts up. If you turn the fan on and off several times the chattering gets shorter, may be down to three or four clicks. Leave it 5 mins and it goes back to full chatter.

Have tried a spare relay unfortunately it is identical to the first and bought at the same time, so it could be a faulty relay batch.

I haven't done anything stupid have I? (well lets be clear I know I have done a lot of stupid things, but in this particular case?)

Alan

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No eletronic guru, I, but a fan of the 'Net and all it can bring.    And a quick Google reveals that Relay Chatter IS a thing, and has causes, effects and cures.  

EG "If the control voltage drops below the specified minimum operating voltage, the relay may chatter. This rapid on and off cycling of the contacts occurs continuously for several seconds, causing excessive heating of the contacts and resulting in severe damage to the relay contacts. This low-voltage chatter condition occurs due to the insufficient pull of the magnet at low voltages to overcome the spring forces that are needed to operate the relay effectively." https://www.appliancedesign.com/articles/91388-switches-relays-cut-the-chatt

So I'd check that your new wiring is delivering full battery volts to the control circuit.   After that I'm as ignorant as the Professor of Ignorance, and Know-Nothing U!   But thereare several other sites to explore.

JOhn

 

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Duh, for somebody who can overdose on Google searches, how come I didn't on this one, I'll put it down to the heat.

Anyway good link, probably the info I need, Thanks

Alan

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