Originally Posted by sixshooter
(Post 1542794)
As a reply to you and DKM:
Not resistance across the coil, unfortunately. That's the 30 to 87 resistance while contacted. And I didn't grab the new alternator to check if warm. Got a link to the relays you're using? Did you use your clamp meter to take a current measurement before the relay? |
Originally Posted by SpartanSV
(Post 1542796)
That's bananas.
Got a link to the relays you're using? Did you use your clamp meter to take a current measurement before the relay? Here's the relays: |
If the current measurement before and after the relay is similar then you can't have 151 ohms across the contacts.
I just measured a very similar relay at 0.2 Ohms across the contacts. |
I'll try a different multimeter tomorrow.
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You my just not be using the meter properly. It sounds as if you are trying to read ohms across the contacts while the fan is on. That won't work. It is confusing the Multimeter.
The correct thing is to measure the amps, and then also measure the voltage drop across the contacts. Then you use Ohm's law to the resistance: Ohms = Voltage / Amperes DNM |
Originally Posted by DNMakinson
(Post 1542810)
You my just not be using the meter properly. It sounds as if you are trying to read ohms across the contacts while the fan is on. That won't work. It is confusing the Multimeter.
The correct thing is to measure the amps, and then also measure the voltage drop across the contacts. Then you use Ohm's law to the resistance: Ohms = Voltage / Amperes DNM I just realized it was DNM and I put DKM earlier. My apologies. I certainly knew there was a K in it but it was in the middle of your last name. |
DMMs use a very small current source to create a voltage across the resisance being measured. If there is already a voltage there, it will muck the reading. I am glad to hear this is the reason for the reading you reported.
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Originally Posted by sixshooter
(Post 1542813)
You're right, I was touching 30 + 87 while the fan was engaged. I didn't realize that would make the difference to anything. For some reason I didn't think the meter was supposed to be bothered by things like that.
I just realized it was DNM and I put DKM earlier. My apologies. I certainly knew there was a K in it but it was in the middle of your last name. |
2 Attachment(s)
Originally Posted by Ted75zcar
(Post 1542815)
DMMs use a very small current source to create a voltage across the resisance being measured. If there is already a voltage there, it will muck the reading. I am glad to hear this is the reason for the reading you reported.
This is how the new wiring was done without a fuse holder. Thankfully it runs much cooler than the store bought holder. |
Originally Posted by DNMakinson
(Post 1542810)
You my just not be using the meter properly. It sounds as if you are trying to read ohms across the contacts while the fan is on. That won't work. It is confusing the Multimeter.
Bench testing the relay in the closed position with no high current leads attached yields an ohm reading of 0.1 to 0.0 on the same meter. I'll try doing the voltage drop and amperage measurement method you described in a bit. |
25.1 amps inline
High current poles on relay during operation: 14.00v 14.02v What does it all mean? |
Relay is fine
Edit: now measure voltage from relay output to fan input. 3 measurements Relay out to chassis Fan in the chassis Relay out to fan in (mV scale) All with fan running and associated current measurements |
Originally Posted by Ted75zcar
(Post 1542860)
Relay is fine
Edit: now measure voltage from relay output to fan input. 3 measurements Relay out to chassis 13.95 Fan in the chassis 13.85 Relay out to fan in (mV scale) 115.0mV All with fan running and associated current measurements Fan in the chassis 13.85 Relay out to fan in (mV scale) 115.0mV At 25.8 amps measured at fan input. |
Length of wire between relay and fan?
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Originally Posted by Ted75zcar
(Post 1542868)
Length of wire between relay and fan?
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Pick up a 40A fuse while you are at it. The relay/wire situatuon sounds fine.
Do you have a thermocouple or an IR temp gauge? |
Originally Posted by Ted75zcar
(Post 1542875)
Pick up a 40A fuse while you are at it. The relay/wire situatuon sounds fine.
Do you have a thermocouple or an IR temp gauge? |
Great. Take temperatures of the components in question after heat soak, as well as other (preferably like materials/colors) surfaces in close proximity to the areas of interest.
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