[tadaska]

Hi guys,

How to correctly test this relay? I'll be using my car battery electricity to make it close. I tested some other relays after watching a YouTube video but this one is different. It looks like the electricity will be going into my multimeter and I would not want to fry it. What is the correct way to test such a relay?

[tadaska]

Anyone? Want it tested before it's dark so I can put it all back together tonight. We got some rain coming tomorrow so I need that scuttle back in place to prevent any water getting in.

[tadaska]

After a bit of thinking I had an idea. I connected my car battery to the terminals 30 and 85. Then I set my multimeter to 20 volts and did tests between the terminal 30 and each of the 87 terminals. Then between the 85 and each of the 87. The 85 and 87 connections read as about 12v and the 30 and 87 connections didn't read. It's seems to me that the relay is ok but I'm no electrician. Quite the opposite. Can anyone tell me if it was a valid test?

[therealdb1]

From your description your test does not prove that the switch is opening or closing. A multimeter would show 0v across 30 and 87 regardless of the switch being open or closed because it is an open circuit.
It is an unusual relay in that the coil is not isolated from the switch which makes testing a bit more awkward.
What you could do is take the +ve of your multimeter directly from the battery terminal opposite to the one you connect to 30 and connect the -ve multimeter lead to 87. Then by applying and removing 12v across 30 and 85 as you did before you should see the multimeter going high or low depending on whether or not the relay is energised.

[tadaska]

Originally Posted by therealdb1

From your description your test does not prove that the switch is opening or closing. A multimeter would show 0v across 30 and 87 regardless of the switch being open or closed because it is an open circuit.
It is an unusual relay in that the coil is not isolated from the switch which makes testing a bit more awkward.
What you could do is take the +ve of your multimeter directly from the battery terminal opposite to the one you connect to 30 and connect the -ve multimeter lead to 87. Then by applying and removing 12v across 30 and 85 as you did before you should see the multimeter going high or low depending on whether or not the relay is energised.

Hi DB1,

Can you explain what I should do in more detail? Including what multimeter setting I should use. Reading it now it looks to me like you are telling me to do exactly what I did This is my first time using a multimeter and me no speak electricity

[tadaska]

After a bit of head scratching I came up with another test.

Red cable from the battery attached to 30. Black cable from the battery attached to 85. The circuit "flap" is now closed (connected). That means both 87 are now red cable? I set my multimeter to 20v and touch black wire to the "-" terminal on the battery and the red wire to 87. Both 87 red as about 12v.

Have I done it right?

[dragerboy]

Go on YouTube, plenty of videos of how to test a relay on there.

[tadaska]

Originally Posted by dragerboy

Go on YouTube, plenty of videos of how to test a relay on there.

This one is different from the ones I saw tested on youtube.

[nick46]

I would say the first test you did was correct. By simply applying power to pins 30 & 85 that should energise the coil and pull the contacts in. When you do this you should hear the contacts opening and closing. When they are open you will have 0V between pins 30 & 87 and likewise between pins 85 & 87. When the coil is energised and the contacts are closed I would say you should have 12V between pins 30 & 87 and likewise 85 & 87.
I may be wrong but that's how I see it.

[nick46]

You could also do a resistance check between pins 30 & 85. Set your meter to OHMS and with no power on the relay put the +ve lead on one pin and the -ve lead on the other. If that part of the circuit is complete, you should get a reading. If there is a break in the circuit you will get nothing. That will prove that part of the circuit.

[tadaska]

Originally Posted by nick46

You could also do a resistance check between pins 30 & 85. Set your meter to OHMS and with no power on the relay put the +ve lead on one pin and the -ve lead on the other. If that part of the circuit is complete, you should get a reading. If there is a break in the circuit you will get nothing. That will prove that part of the circuit.

It reads 96 ohms between 30 and 85 what does that mean?

[nick46]

I would say it means that part of the circuit is complete and as such is fine.

[therealdb1]

You are right this is not a conventional relay but it can be tested easily.
The test you have done confirms that the switch (flap) is closed with power applied but not that it opens with power off.
Connect 30 to the battery +ve as you did previously.
Set the multimeter to 20v dc and connect the +ve lead to 87.
Connect the multimeter -ve lead to the battery -ve.
At this point the multimeter should read 0v.
Leaving everything as above connect the battery -ve to 85.
You should hear the relay click and the multimeter should read 12v.
Disconnect 85, the relay should click again and the multimeter will go back to 0v.
This proves that the relay is operating as it should.

You have already checked the dc resistance of the coil at 96 ohms which sounds about right. You could do a more elegant check by measuring the relay coil current.
Connect 85 to battery -ve.
Connect multimeter -ve to 30.
Set multimeter range to 200mA or a higher range.
Connect multimeter +ve to battery +ve, the relay should click and you should get a reading of around 125mA.

If you have all of the above the relay is ok.

[tadaska]

Originally Posted by therealdb1

You are right this is not a conventional relay but it can be tested easily.
The test you have done confirms that the switch (flap) is closed with power applied but not that it opens with power off.
Connect 30 to the battery +ve as you did previously.
Set the multimeter to 20v dc and connect the +ve lead to 87.
Connect the multimeter -ve lead to the battery -ve.
At this point the multimeter should read 0v.
Leaving everything as above connect the battery -ve to 85.
You should hear the relay click and the multimeter should read 12v.
Disconnect 85, the relay should click again and the multimeter will go back to 0v.
This proves that the relay is operating as it should.

You have already checked the dc resistance of the coil at 96 ohms which sounds about right. You could do a more elegant check by measuring the relay coil current.
Connect 85 to battery -ve.
Connect multimeter -ve to 30.
Set multimeter range to 200mA or a higher range.
Connect multimeter +ve to battery +ve, the relay should click and you should get a reading of around 125mA.

If you have all of the above the relay is ok.

Thanks DB1, will get that relay out again tomorrow and test it as you described so I'm 100% sure it's ok.