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Beware of Amazon's class t fuses

Osmethne

Solar Enthusiast
Joined
Aug 18, 2023
Messages
138
Location
Salt Lake City
So I'm looking around this forum randomly and I read somewhere of someone using an IR camera to look for hotspots in their system. I though that's a great idea. I already have one of those. Let's see how everything is doing.

FLIR_20240610_014706_578.jpg

Oh hello. What have we here?

Well this isn't good.

20240610_135259.jpg


I know what you're thinking. You're thinking I didn't tighten it down enough or I didn't crimp it correctly. But you would be wrong. The lugs are still torqued down and the wires won't come out with a decent amount of force.

20240610_142344.jpg

Around the beginning of the year I got some cheap class t fuses from Amazon. I figured they were better than nothing while I was researching things. But now I think I would have been better off not including these.

The system was still functioning normally but obviously I can't just leave it like this so I shut it all down and remove all the melted things.

Then something odd happens which it's possible it's a coincidence, the MPPTs on the inverter stopped working. Also the inverter doesn't work unless I shutdown the batteries. On top of this the inverter is an SGP IP6048 so getting a replacement is going to be like pulling teeth. I'm probably better off fixing it myself.

I do have some reputable class t's coming in from donrowe.com.
 
So I'm looking around this forum randomly and I read somewhere of someone using an IR camera to look for hotspots in their system. I though that's a great idea. I already have one of those. Let's see how everything is doing.

View attachment 221187

Oh hello. What have we here?

Well this isn't good.

View attachment 221188


I know what you're thinking. You're thinking I didn't tighten it down enough or I didn't crimp it correctly. But you would be wrong. The lugs are still torqued down and the wires won't come out with a decent amount of force.

View attachment 221193

Around the beginning of the year I got some cheap class t fuses from Amazon. I figured they were better than nothing while I was researching things. But now I think I would have been better off not including these.

The system was still functioning normally but obviously I can't just leave it like this so I shut it all down and remove all the melted things.

Then something odd happens which it's possible it's a coincidence, the MPPTs on the inverter stopped working. Also the inverter doesn't work unless I shutdown the batteries. On top of this the inverter is an SGP IP6048 so getting a replacement is going to be like pulling teeth. I'm probably better off fixing it myself.

I do have some reputable class t's coming in from donrowe.com.
The lug and the fuse should be directly adjacent, remove those washers between them. Also is there a fuse holder or is all the force on the fuse itself?

Screenshot_20240610_195702_Chrome.jpg
 
100000000000% agree with the above comments.

If they are who they say they are I'd say they should be a quality product, I have 0 experience with them and probably wouldn't use them.

Edit to add , I'm glad you caught it before bad things happened.
 
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Oh I think I see why, the lugs seem extra long so he's shimmed them with washers to get the clearance to the fuse body. Definitely better off with nothing than that
 
Yeah, I'd blame those washers long before the fuse (which could still be crap)

I see what you mean. It probably didn't help but that by itself it's sort of hard to believe it could cause this much damage.

This is the fuse btw. https://www.amazon.com/gp/product/B0BHSNYHHH/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Oh I think I see why, the lugs seem extra long so he's shimmed them with washers to get the clearance to the fuse body. Definitely better off with nothing than that
Seems possible. Maybe intermittent content could have caused it. It may not be apparent in the picture but that side with the longer lug was way worse than the other side.

ok it’s in red but what’s the temperature?

I think the flir app said 134c could be wrong on that though.
 
I know everyone's perfect way is different than another, but I am a fan of as simple as possible.

Do any of you great minds on the forum think over-fusing/switching has it's pitfalls as well? That is what I have been thinking lately when I see each failure mode posted here. Each section where you go from wire to device, back to wire has many points of failure. At some point (after the basics in my opinion) introducing additional switches, etc. just sets the whole system up for failure.

One other thing that can be a danger is short pieces of ultra stout wire. A bunch of little connections. Even if torqued, they could back themselves off, or be a bit kinked just by nature of being a big chunk of barely bendable copper.
 
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I see what you mean. It probably didn't help but that by itself it's sort of hard to believe it could cause this much damage.

This is the fuse btw. https://www.amazon.com/gp/product/B0BHSNYHHH/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1


Seems possible. Maybe intermittent content could have caused it. It may not be apparent in the picture but that side with the longer lug was way worse than the other side.



I think the flir app said 134c could be wrong on that though.
Wow!
They are clearly showing the washers wrong... That's crazy...

Again, glad you caught it before bad things happened.

It would be pretty nice if you cut it open for the community so we can see what the insides are like...
 

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I know everyone's perfect way is different than another, but I am a fan of as simple as possible.

Do any of you great minds on the forum think over-fusing/switching has it's pitfalls as well? That is what I have been thinking lately when I see each failure mode posted here. Each section where you go from wire to device, back to wire has many points of failure. At some point (after the basics in my opinion) introducing additional switches, etc. just sets the whole system up for failure.

One other thing that can be a danger is short pieces of ultra stout wire. A bunch of little connections. Even if torqued, they could back themselves off, or be a bit kinked just by nature of being a big chunk of barely bendable copper.
I'm far from a great mind compared to some here, but I agree overdoing it could have pitfalls, every connection adds resistance; regardless if installed properly and PM'd properly there should be zero issues.
 
I see what you mean. It probably didn't help but that by itself it's sort of hard to believe it could cause this much damage.
It definitely is. Steel is a bad conductor (compared to copper).
There are other posts on here with melted fuse holders/connections caused by this exact issue.
 
Also, that thick washer between the cable and fuse looks like lock washer. Those only work when directly in contact with the nut. Even then they barely work.
 
I know everyone's perfect way is different than another, but I am a fan of as simple as possible.

Do any of you great minds on the forum think over-fusing/switching has it's pitfalls as well? That is what I have been thinking lately when I see each failure mode posted here. Each section where you go from wire to device, back to wire has many points of failure. At some point (after the basics in my opinion) introducing additional switches, etc. just sets the whole system up for failure.

One other thing that can be a danger is short pieces of ultra stout wire. A bunch of little connections. Even if torqued, they could back themselves off, or be a bit kinked just by nature of being a big chunk of barely bendable copper.
No, I am happy with my triple redundancy (contacor, fuze, breaker), but I’m not trying to pass current through steel either.

With a proper crimp, you don’t have a bunch of little wires; they are cold welded together.
 
I had something very close to that fuse and holder from Amazon. Sent it back because of recommendations from members on here.
After ordering Blue sea fuse holders, I realized just how poorly made the cheap ones were.
 
So I'm looking around this forum randomly and I read somewhere of someone using an IR camera to look for hotspots in their system. I though that's a great idea. I already have one of those. Let's see how everything is doing.

View attachment 221187

Oh hello. What have we here?

Well this isn't good.

View attachment 221188


I know what you're thinking. You're thinking I didn't tighten it down enough or I didn't crimp it correctly. But you would be wrong. The lugs are still torqued down and the wires won't come out with a decent amount of force.

View attachment 221193

Around the beginning of the year I got some cheap class t fuses from Amazon. I figured they were better than nothing while I was researching things. But now I think I would have been better off not including these.

The system was still functioning normally but obviously I can't just leave it like this so I shut it all down and remove all the melted things.

Then something odd happens which it's possible it's a coincidence, the MPPTs on the inverter stopped working. Also the inverter doesn't work unless I shutdown the batteries. On top of this the inverter is an SGP IP6048 so getting a replacement is going to be like pulling teeth. I'm probably better off fixing it myself.

I do have some reputable class t's coming in from donrowe.com.
Why is there 2 washers under the lug.. not cool even for a good blue sea ClassT setup…
 
I see what you mean. It probably didn't help but that by itself it's sort of hard to believe it could cause this much damage.

This is the fuse btw. https://www.amazon.com/gp/product/B0BHSNYHHH/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1


Seems possible. Maybe intermittent content could have caused it. It may not be apparent in the picture but that side with the longer lug was way worse than the other side.



I think the flir app said 134c could be wrong on that though.
Not to pile on. But I hope you understand that what you have done is a big deal.
 
Wow!
They are clearly showing the washers wrong... That's crazy...

Again, glad you caught it before bad things happened.

It would be pretty nice if you cut it open for the community so we can see what the insides are like...

Yeah I recall sort of wondering what the order of these fasteners was supposed to be. I was a while ago. I guess I figured it was best to go with what the documentation said.
 
There is a lot of ways to say "weakest link in a chain" but this one is good, and makes you think.

From a reliability of systems chapter in a book by Jaroslav Menčík
A practical conclusion is that “the reliability of a series system is always lower than the
reliability of any of its components”


You have a chain of wires, switches and fuses in series (in my opinion, the less the better). The worst component inserted into that chain makes the whole series of parts as good as that component, minus the failure rate of the other components as well.
 

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