It's still odd to me it only gets hot upstream of the relay, at the relay itself, and nowhere else, even if that wire is much larger diameter. But I don't have an EE.

I went ahead and bought a AC/DC amp meter from Amazon for $30 because of Deal Days sale:


One day it will be used.

 

I would kindly remind you of post number two in this thread, Steve.

Specifically the sentences talking about physical obstructions to the fan and free rotation and such.

"I would start with the fans, to see if there are any physical obstructions keeping them from rotating freely.
Next, I would check how much power (amps) they are drawing.

These two steps would eliminate the biggest source of power consumption if they check out fine."

 

You are correct, as usual.

It turned easily by hand and I didn't have an amp meter yet so I did what I could. The fan must have something wrong internally to draw so much more startup energy than it once did. The fan was the most expensive piece to replace at $125 plus shipping. The 80a relay was only $4. I already had the 10 gauge fuse holder in my box of electrical connections. I'm glad the other components are now upsized for reliability regardless of the extra trouble I went to.

 

Impulse buy of the day.

 

Spal advises using 40 amp fuse and 40 amp relay with this fan! Running draw is 18 or 21 maximum depending upon where you read, and I know startup is higher.


Really surprised they use 14 gauge wire.

 

Did you use their wiring kit and it was 14 gauge the whole way? Or was it just a short length of wire off the motor that was 14 gauge?

 

I did not buy their kit. Their wire is at least 24 in from the fan motor. I will hopefully get a closer look at the new one tonight. I'm reasonably confident my 10 and 12 gauge wire with 80 amp relay will be more substantial.

Is it possible my 30 amp fuse was just never large enough and that created heat in just that wire and relay? Do not know if that's possible.

 

Weird stuff can happen when you restrict large currents.

During the runup to the 2016 presidential election, when I was working in New York, one of our news vans was out at the Democratic National Convention in Philly. Due to a snafu in the booking, the venue provided us with ashore-power connector that we didn't have the proper cable for. (It was a 3 phase, 50 amp circuit, and the truck expects single-phase 120v 30A.) Rather foolishly, the truck operator cobbled together a collection of adapters and cables which allowed him to plug in the truck, and part of this consisted of a 20 foot extension cord with a 15 amp plug and rating, I think it was an 18 AWG cable.

Anyway, he fires up the truck, gets the air conditioner going, raises the satellite dish and fires up the transmitter, and basically just starts doing truck stuff. And it works for a while. Then he starts to smell something. Something burn-ey.

Long story short, the 30A power receptacle on the side of the truck was melting. The 15A extension cord was also in poor shape, but the big 30A twist-lock plug going into the side of the truck was sagging about 20° from horizontal, and smoke was coming out of it.

I have utterly no idea what caused that.

Humorous coda: when you're parked inside the secure area at the Democratic National Convention, surrounded by FBI and Secret Service, you don't want smoke to be coming out of your vehicle. That makes the men with the guns nervous.

 

A fuse is just a short wire that burns. Wire ampacity is somewhat rated similarly - it's not that copper burns if you go over X amps for a certain gauge, the sheath melts. PVC covering melts much lower than TXL. 14ga is perfectly sufficient for a foot at 20a sustained if the sheathing doesn't melt. Smaller gauge does accrue higher resistance - that resistance is converted to heat.

The main critique I have of your setup is your crimper - I'm not a fan of stake crimpers - they're very inconsistent, tend to pierce coverings, only really contact a small area that leaves the rest of the wire open to oxidation. A ratcheting crimper is betterer - repeatable crimps that compress a larger area, won't pierce the heatshrink buttsplices I like to use (oxidation), better conduction. I suspect you've got a bad joint on the relay - and that heat is conducting down the line somewhere.

I'm pretty much guessing at this point though - mostly because of my hatred for stake crimps.

 

I Googled ratcheting crimper and I think I own one. I didn't buy it, I inherited a bunch of electrical stuff from a guy who installed home audio and electronic systems for many years. I've got boxes of thousands of crimp connectors, most of them red ones with various ends to be screwed down or otherwise connected.

I also inherited a telephone receiver that has a couple of clamps on wires hanging out of it. I guess you could go up to someone's exterior phone box and make long-distance calls.

 

https://www.summitracing.com/ga/parts/ttn-11477 is what I currently have after my original one wore out. https://www.harborfreight.com/30-pac...ors-66729.html are in my box for less-critical joints, https://www.delcity.net/store/Perma!...12022.h_812023 have a longer barrel and better seal.

 

When I was in high school, a friend and I did exactly this. We typically would open the green can in the neighborhood, rather than hitting individual houses.

I also kind of agree w/ gooflophaze about your crimper. It's not impossible to make a good crimp with the one you have, but using a ratcheting crimper makes it easier and more pleasant. I own two of them. (One at home, one at work.)

 

Old fan running- 21.5 amps
New fan running- 22.4 amps

Resistance across relay- 151 ohms
Resistance across fuse and its wire (measured at relay and main 80a fuse output)- 22 ohms

Fuse wire temperature around 245 degrees Fahrenheit during continuous operation of fan. 80a relay also hot. All other wires good temp.

Power entering main 80a fuse 13.8-14v.

Fan ground wire to chassis was replaced with 10 gauge now.

I'm not sure what the max temperature of the relay, wire, or fuse holder might be but it seems warm.

Heading to Lowe's for the reccomended crimper. Not sure what to do otherwise. Maybe I'll increase the size of the high current lead from the relay to the fan to 10 gauge.

40 amp fuse is holding.

I'm lost unless this type of heat is in the realm of acceptability. Totally lost.

 

Those resistance measurements are whack. 20A through 151 ohms would be ~3000 volts.

Do you have any local friends who are EEs or electronics technicians?

This honestly shouldn't be this complicated.

 

I'm guessing that was the coil reading. 1.1 watt coil is sensible.

EDIT: However, if across the contacts, one does not know if contacts are fritted or not, so a low voltage measurement is not valid. Much better to measure current and voltage drop on a set of closed contacts. Especially Silver Tin Oxide.

EDIT(2): 22 Amps should not blow a 30A fuse, whether slow or fast acting. IIRC, your fuse did not blow on start-up or locked rotor, but after fan was running for a minute or so.

Is Alternator hot?

 

This seems wrong.

Assuming 14v and 20a, that's 280 watts being dissipated across the relay. While this is less than the output of the sun, it's quite a bit more than any normal relay could sink without bursting into flame.

I'm not exaggerating here. 280 watts across the contacts of automotive style relay would cause it to melt, and emit smoke and fire.

 

That's obviously the resistance across the coil. Totally reasonable value.

 

Switched to the other 80a relay (it was a two pack) and measured an identical 151 ohms when contacts closed and fan running. Not normal?

I changed the fuse holder wire segments out and ran a new 10 gauge wire (employing better crimpers) from the fuse block to the 40a fuse and from the 40a fuse to the 80a relay.

I employed a new 10 gauge wire from the relay to the fan utilising macho crimpers.

I moved the fan ground wire (already 10 gauge) to a different chassis location and made use of a star washer to ensure excellent contact. I also re-squoze the crimp.

Tested.

Fuse wires not nearly as hot to the touch. Fuse itself gets warm but that's expected, I guess. Relay gets good and warm but not as bad.

Startup for fan measured at 31amps for a flash and then steady at 22 amps.

I'm trying to decide if this is workable. If it keeps working and there's no fire = solution?

Should I just send it?

 

The gravity of this reality is not lost on me.

 

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.