Relay Life for Relay #2

After some 10 days of continuous operation the test board flash memory was full with over 2 million cycles of data at a constant 2 Amps using a constant current generator. Below is a picture of the actual relay, nearly destroyed when it was removed from its original PCB.

 

I chose this recovered relay because it was damaged. It was surprising that despite the abuse during removal the results, below, show there was no real degradation over 2 million cycles at the rated contact current capacity. Perhaps 30 volts at 2 Amps would give a different result compared with 12 volts at 2 Amps. But for now I am completely satisfied that this relay, of which I have recovered dozens, will be a suitable basis for use as a 50 watt 6m changeover relay.

 

To put this in context the ADC returns a reading of 214 for 0.685volts. For each cycle 16 readings (the graph was wrongly label as the sum of 8 readings) of the voltage across the relay contacts is taken, summed, and stored for the analysis. So a sum of say 200 means there was 40 mV across the terminals. With 2 Amps passing through the contacts that means the resistance was 20 milli-ohm (0.020 ohm).

That is probably enough from me on the subject of relay life. I'm satisfied that operated within the specified ratings a relay, even when recovered, is not going to wear out. All you have to watch out for is  relays re-printed with over-stated specifications sold by the Chinese on Ali-express etc. Similar to the ludicrous ratings printed on 18650 lithium batteries they sell.

73's