What's going on here?

[Skunksmash]

I'm having a strange electrical problem. Well, it seems strange to me at least. I did the H4 headlight bulb conversion on my 87. Bought some better headlights off ebay, and wow what a difference in night time visibility. I used those Hella brand relays, that have a fuse in them. Put them up by the battery, so they'd be easy to deal with in the event that I ever needed to work on them or anything. As you can see, they're melting. Wouldn't a short that was capable of generating that kind of heat, blow the fuses?

But it hasn't. You can see that one fuse, has just completely melted. Well, the plastic has melted off of the fuse, anyway. But the metal is still there, and still functioning. This all seems pretty strange to me. That the fuse didn't blow. They're just 25 amp fuses, for these 25 amp relays. Used 18 gauge wire, to wire up the headlight conversion. So I don't think its anything to do with the wire diameter.

[bbbc10]

Sounds like you need to upgrade ur wiring....when i put hids in mine i put in a relay harness an never had any problems with my wiring etc

[Skunksmash]

[Skunksmash]

Originally Posted by bbbc10

Sounds like you need to upgrade ur wiring....when i put hids in mine i put in a relay harness an never had any problems with my wiring etc

Well I did run all new wiring for the headlight upgrade. The old stuff just looked too old and crusty so I went ahead and replaced it.

[Mr.Chevy4x4]

What is the module right under your relays? EDIT: NVM, just realized it's your battery. It looks to me like the relays are getting extremely hot (more amperage than they are rated for?) Looks like the heat originated from the bottom looking at the one on the right. Maybe the fuse connectors are too small and are getting hot conducting the current?

Maybe get some 40/30 relays and in line fuse holders, and swap them out. Rated at 40 for startup and 30 continuous.

Mike

[69heavychevy]

I had a similar issue when I had my 69.

I had replaced all the fuses with brand new ones for piece of mind. Soon after I was melting wires but the fuses wouldn't blow (they were glass fuses).

After a few days of head scratching, I found that the new fuses weren't making good contact due to corrosion left behind by the original fuses I removed.

Cleaned up the contacts on the fuse box and problem was solved.

[Dead Parrot]

Put an ammeter on the headlight and check actual current draw. Depending on heat rating, 18ga wire maxes out around 16 amps.

Any chance the plastic is melting from exposure to battery fumes or indirect heat?

Did they melt immediately or several weeks later? If later, maybe battery fumes corroded the contacts leading to high heat.

[Skunksmash]

That is the weird thing. I have had these relays for about 2 years, and they were just fine up until about 2 months ago. I noticed a problem, and tried simply replacing the fuses to see if that would work. The headlights began cutting out here and there, so I checked the relays and found that they were melting.

I'll get my multimeter on there and see how many amps are flowing through.

[SCOTI]

Originally Posted by Skunksmash

That is the weird thing. I have had these relays for about 2 years, and they were just fine up until about 2 months ago. I noticed a problem, and tried simply replacing the fuses to see if that would work. The headlights began cutting out here and there, so I checked the relays and found that they were melting.

I'll get my multimeter on there and see how many amps are flowing through.

Relays in place & w/o issue for 2yrs & recently started this problem within the last 2 months? I would start w/what has changed in the last 2 months. That said, wire gauge seems small for the application.

[Skunksmash]

Originally Posted by SCOTI

Relays in place & w/o issue for 2yrs & recently started this problem within the last 2 months? I would start w/what has changed in the last 2 months. That said, wire gauge seems small for the application.

Still gotta get that ammeter on there, but I haven't done anything to it in that 2 month period. All I have done was fix a bad negative battery cable, that was causing a no start condition on the truck. The copper inside had become too corroded. Nothing else other than that.

[SCOTI]

Originally Posted by Skunksmash

Still gotta get that ammeter on there, but I haven't done anything to it in that 2 month period. All I have done was fix a bad negative battery cable, that was causing a no start condition on the truck. The copper inside had become too corroded. Nothing else other than that.

The change within the last 2months was w/the grounding. What was the 'fix'? Sounds like that affected things.

[Skunksmash]

It was only corroded at the very end of the cable. So I cleaned it all off pretty well, and wam bam the truck starts right up. Probably need to completely replace the cable, but I know what the cause is now, and I'll get to the cable later on.

But I should say that this melting was starting to happen before that battery cable issue. Could still be related, but I don't think it was anything I did to the cable, since it was going on a bit before that. The cable issue I fixed last week.

[SCOTI]

Originally Posted by Skunksmash

It was only corroded at the very end of the cable. So I cleaned it all off pretty well, and wam bam the truck starts right up. Probably need to completely replace the cable, but I know what the cause is now, and I'll get to the cable later on.

But I should say that this melting was starting to happen before that battery cable issue. Could still be related, but I don't think it was anything I did to the cable, since it was going on a bit before that. The cable issue I fixed last week.

Corrosion at the end of a batt cable usually means it's also within the cable. The more corrosion, the greater resistance. The greater resistance could be what impacted the 'smallish' wire size used. I would replace the cables w/2gauge or larger & use 14ga for the relays as well.

[Skunksmash]

So its possible the bad negative battery cable, could be causing the whole issue?

[SCOTI]

Originally Posted by Skunksmash

So its possible the bad negative battery cable, could be causing the whole issue?

Poor quality connections stress electrical systems. That stress can/will show up where a weak link is. Check w/board member gmachinz about what wire size he utilizes on his headlight relay systems for better insight.

At the least, replace any cable that indicates corrosion w/the biggest upgrade you can. Try to keep POS & ground cables equally sized & you can never have too many grounds. For reference, I have 4ga grounds front to back on my dually on each frame rail: 2@ core support, engine block, & the cab (1 @ each side/rail for each). My battery to frame ground is sized the same as my POS cable (1ga). Overkill? Yep. Ground/electrical issues? Nope.

[wilkin250r]

It's doutbful the negative battery cable is was the problem. Yes, it has some effect, but your typical automotive starter is about 500 amps. 25 amps is nothing. Even if your battery connection is so corroded it won't allow your starter to turn, you can still usually pull 25 amps off that terminal.

I'm more worried about the amperage in general, and your wiring. I don't know exactly what type H4 bulb you are using, but if it's a high-output, you might be pulling 100 watts, which is about 10 amps@12V.

I'm not sure how you're wired, if you have dual headlights or not, but if you have two of them, and you're pulling 20 amps, add some losses into the system, you could be very close to the max rating of that relay, and certainly higher than 16 gauge wiring. A lot of your heat might be coming from your wires, as copper is an excellent conductor of heat.

[Skunksmash]

Got some time to work on the truck today. Yes one of the wires, a hot wire, is getting very hot (temp). IR gun says 116 degrees, after being on for only a few minutes. The rest of the wires all say 75 degrees. The main wire getting too hot, is the long wire that I have running between the two sides of the truck. One wire powers the other side's headlights as well.

Hot wire on the battery was getting a little warm too, but I'm not sure if that's normal.

[Skunksmash]

Another thing I found:


One of my cheapo chinese headlight bulbs has completely crusted over with rust. The base of the bulb, is severely corroded. But NOT the electrical contact points. Maybe this is what I get for buying the cheapest headlight kit ebay has to offer. It came with 4 new headlights, that looked really good. As well as 4 new bulbs. To help hold the bulbs in, there is a rubber cap on the back of each headlight, which is about 3 inches in diameter. Each of those 4 caps is pretty badly melted, where it gets close to the bulb.

The bulb that I'm referring to with the rust, apparently melted its rubber backing cap so badly, that it began to allow moisture onto the base of the bulb. And the rust began aggressively eating up the base of the bulb. I have no idea if this could be related to my melting relay problem, though. The rusty bulb was still working fine.