Ceramic fuses, What are they worth to ya? Options

[JamesM]

Stop making sense.

I refuse! (IMG:style_emoticons/default/biggrin.gif)



Grabbed one of the brand new Littlefuse GBCs from one of the standard electronic supply chains and gave it to my assistant Beavis for some destructive testing.

@wonkipop Im no materials scientist, but I don't think these are plastic.

Knowing we were between the temperature of burning butane and the melting point of aluminum id estimate we tested to somewhere in the 1500 degree ballpark, aka mildly warmer than you want your fuse panel to ever be. And we cooked it for a good while.

ZERO deformation, zero burning, zero melting (other than the element) only real change to the body funny enough (other than adding a nice carbon coating) was the discoloration of the more vibrant red body to looking like the faded light pink of one of the 50 year old originals. (you can see a bit of it if you zoom in) Makes me wonder if the color of the original fuses isnt actually the original color but is the color of them oxidized for 50 years.

Sure if you get a cheap knock off plastic pill intended to look like a fuse you may have some issues, but if you buy an actual fuse from an actual fuse manufacturer I suspect you might be fine. But you do you.

Vendor says the factory has 4700 of the 8 amp in stock currently so we should be good for the next couple weeks at least.

[Superhawk996]

I mean it would have been impressive enough had you done the amperage testing.

But sheesh . . . Fire testing them . . . And squeezing in a Beavis and Butthead reference.
(IMG:style_emoticons/default/pray.gif)

Now do the plastic fuses (IMG:style_emoticons/default/av-943.gif)

[Artfrombama]

My thoughts;
The aluminum fuse element over time has a dissimilar metal corrosion (galvanic corrosion) with the metal of the fuse block contacts... Viola, electrical resistance/heat. Even though the circuit isn't overloaded enough to blow the fuse, the cheepie fuse melts.

I think we all have seen fuse contacts that have overheated and turned color and lost some spring tension.

It's a poor design even with the best fuses.

[Superhawk996]

My thoughts;
The aluminum fuse element over time has a dissimilar metal corrosion (galvanic corrosion) with the metal of the fuse block contacts... Viola, electrical resistance/heat. Even though the circuit isn't overloaded enough to blow the fuse, the cheepie fuse melts.

Very plausible.

But I think goes back to what JamesM was arguing that high resistance was the source of the problem not the plastic per se? I know I’ve seen fuse blocks with plenty of questionable “patina”.

Regardless I’ve seen enough wiring done with wire nuts, electrical tape, and just twisting wires together that I’m just surprised that we still have a decent population of 914’s that has defied the abuse and the odds and continue to survive.

And for the record - put me down for some ceramic bits as a kit . . . But I’m out at $18/fuse (IMG:style_emoticons/default/lol-2.gif)

[JamesM]

My thoughts;
The aluminum fuse element over time has a dissimilar metal corrosion (galvanic corrosion) with the metal of the fuse block contacts... Viola, electrical resistance/heat. Even though the circuit isn't overloaded enough to blow the fuse, the cheepie fuse melts.

I think we all have seen fuse contacts that have overheated and turned color and lost some spring tension.

It's a poor design even with the best fuses.

We are only assuming what the element is made of based on appearance but have no idea what it actually is, could be tin, or some alloy, whatever. Again I leave that up to the material scientists making the fuses. As shown vintage littlefuses appear to use the same element material that they do today (and also dont melt) so its not even that you are looking for a period correct material so much that you are looking for a fuse from one specific manufacture who is not currently making them. If you think they are somewhat better with no actual data to show why then... cool... again you do you.

BTW my vote was that they should be 6 bucks a piece, I mean after all they are not made anymore right? Get em while you can! And then I guess just hope they don't do what a fuse was designed to do and pop cuz then you are just (IMG:style_emoticons/default/stromberg.gif) out of luck.

ohhhhh I got a an idea! Install some slightly smaller fuses inline to fuse your "show fuses" so you don't accidently blow them. (IMG:style_emoticons/default/poke.gif)

In all seriousness though its a sacrificial part, if you don't ever plan on putting 12v to your electrical system then ok, but if you actually drive your car you are going to have to come to terms with the current availability of perfectly functional fuses.

I was going to mention something about the dissimilar metals at the connections to every single lightbulb in your electrical system protected by these fuses in question, but then I worry it would cause some of you out there to loose sleep at night. Speaking of, how many of you fuse aficionados still have undamaged factory original backpad lights? I feel like people are going to notice that long before looking at your fuses. (IMG:style_emoticons/default/biggrin.gif)

[JamesM]

Regardless I’ve seen enough wiring done with wire nuts, electrical tape, and just twisting wires together that I’m just surprised that we still have a decent population of 914’s that has defied the abuse and the odds and continue to survive.

But have you seen an ignition harness fashioned out of a section of repurposed 120v indoor electrical cord?

Seriously anyone worried this much about fuses is welcome to bring me your car and ill point out all the areas you should probably be more concerned with.

[wonkipop]

Stop making sense.

I refuse! (IMG:style_emoticons/default/biggrin.gif)



Grabbed one of the brand new Littlefuse GBCs from one of the standard electronic supply chains and gave it to my assistant Beavis for some destructive testing.

@wonkipop Im no materials scientist, but I don't think these are plastic.

Knowing we were between the temperature of burning butane and the melting point of aluminum id estimate we tested to somewhere in the 1500 degree ballpark, aka mildly warmer than you want your fuse panel to ever be. And we cooked it for a good while.

ZERO deformation, zero burning, zero melting (other than the element) only real change to the body funny enough (other than adding a nice carbon coating) was the discoloration of the more vibrant red body to looking like the faded light pink of one of the 50 year old originals. (you can see a bit of it if you zoom in) Makes me wonder if the color of the original fuses isnt actually the original color but is the color of them oxidized for 50 years.

Sure if you get a cheap knock off plastic pill intended to look like a fuse you may have some issues, but if you buy an actual fuse from an actual fuse manufacturer I suspect you might be fine. But you do you.

Vendor says the factory has 4700 of the 8 amp in stock currently so we should be good for the next couple weeks at least.

hats off to you mate. nothing like an empirical test.
the cores sure pass that. (IMG:style_emoticons/default/beerchug.gif)
real deal.

[wonkipop]

My thoughts;
The aluminum fuse element over time has a dissimilar metal corrosion (galvanic corrosion) with the metal of the fuse block contacts... Viola, electrical resistance/heat. Even though the circuit isn't overloaded enough to blow the fuse, the cheepie fuse melts.

I think we all have seen fuse contacts that have overheated and turned color and lost some spring tension.

It's a poor design even with the best fuses.

We are only assuming what the element is made of based on appearance but have no idea what it actually is, could be tin, or some alloy, whatever. Again I leave that up to the material scientists making the fuses. As shown vintage littlefuses appear to use the same element material that they do today (and also dont melt) so its not even that you are looking for a period correct material so much that you are looking for a fuse from one specific manufacture who is not currently making them. If you think they are somewhat better with no actual data to show why then... cool... again you do you.

BTW my vote was that they should be 6 bucks a piece, I mean after all they are not made anymore right? Get em while you can! And then I guess just hope they don't do what a fuse was designed to do and pop cuz then you are just (IMG:style_emoticons/default/stromberg.gif) out of luck.

ohhhhh I got a an idea! Install some slightly smaller fuses inline to fuse your "show fuses" so you don't accidently blow them. (IMG:style_emoticons/default/poke.gif)

In all seriousness though its a sacrificial part, if you don't ever plan on putting 12v to your electrical system then ok, but if you actually drive your car you are going to have to come to terms with the current availability of perfectly functional fuses.

I was going to mention something about the dissimilar metals at the connections to every single lightbulb in your electrical system protected by these fuses in question, but then I worry it would cause some of you out there to loose sleep at night. Speaking of, how many of you fuse aficionados still have undamaged factory original backpad lights? I feel like people are going to notice that long before looking at your fuses. (IMG:style_emoticons/default/biggrin.gif)

correct re element. some cheapos have been reported to be aluminium, but all may not be. hard to know what proppa ones are but its bound to be thought through even if silver.

bosch went to brass copper in the 90s when lead got banned.
they used to use lead/tin which was very good and worked well with the fuse contacts in the board in terms of corrosion etc.

i really don't know when it comes to the latest silver ones.
i'd guess if the cores are good ala flame test then the filaments with them are similarly serious. (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/biggrin.gif) the fuse material is proppa stuff too. (IMG:style_emoticons/default/beerchug.gif)

anyway i believe you and thats a good source of fuses you have. (IMG:style_emoticons/default/beerchug.gif)

-----

folks just got to watch out for the countefeit stuff from you know where. (IMG:style_emoticons/default/biggrin.gif)

[JamesM]

hats off to you mate. nothing like an empirical test.
the cores sure pass that. (IMG:style_emoticons/default/beerchug.gif)
real deal.

To many years as an engineer and working QA, I hate to let things rest without having actual data. This seemed like the quickest way to get some.

Now we know, Littlefuse still makes good GBC fuses. These were brand new from Dijikey so nothing out of the ordinary.

TBH there was a small part of me hoping they were crap because watching one melt would be sort of fun too. So if anyone knows of any fuses of suspect quality feel free to send them my way for testing.

[wonkipop]

hats off to you mate. nothing like an empirical test.
the cores sure pass that. (IMG:style_emoticons/default/beerchug.gif)
real deal.

To many years as an engineer and working QA, I hate to let things rest without having actual data. This seemed like the quickest way to get some.

Now we know, Littlefuse still makes good GBC fuses. These were brand new from Dijikey so nothing out of the ordinary.

TBH there was a small part of me hoping they were crap because watching one melt would be sort of fun too. So if anyone knows of any fuses of suspect quality feel free to send them my way for testing.

i don't think i have any (IMG:style_emoticons/default/stromberg.gif) box fuses lying about in the workshop here to give the flamethrower to, but am tempted now to see if i can get hold of some at autobahn/et al to give them a test.

mikes got some plastic ones in a bag somewhere he transfers the copper/brass off.
when he is around tomorrow i'll see if i can get one from his stash for a test. (IMG:style_emoticons/default/biggrin.gif)

[bdstone914]

This is why you don't want thermoplastic fuses.
This is the result of what will happen to the plastic on the relay board when the fuse to terminal resistance is high. The board melts and the terminals discolor and distort.
I have seen this on several relay boards I have restored.

[JamesM]

This is why you don't want thermoplastic fuses.
This is the result of what will happen to the plastic on the relay board when the fuse to terminal resistance is high. The board melts and the terminals discolor and distort.
I have seen this on several relay boards I have restored.

That is also the highest current circuit on the car and maybe the most common to dead short to ground given it also feeds the AAR. Definitely don't want high resistance there. Seen quite a few melted there. Not sure its due to a bad fuse though as i have never seen a plastic fuse in a 914. Still wouldn't want one there though.

The riveted design of the relay boards doesn't help either

[Artfrombama]

The riveted design of the relay boards doesn't help either

Neither does the tiny surface area that contacts the fuse