Automotive Fuse Comparison with a Milli-Ohm Meter

John from Ogden Educator Posted   Latest  
Demonstration
Electrical
Parts

If you thought all automotive fuses were of the same quality, think again! We compare four fuse brands using a Hioki RM3548 milli-ohm meter, the results are unbelievable! See the video and the attached file for the specifications and results. I was very impressed with the Littelfuse and Bussman fuses; not at all impresses with the other "Brands".

After shooting the video I learned that Littelfuse makes their own fuses and supplies fuses to 80% of the world's automotive market. I was told that Bussman no longer makes their own automotive fuses, they are supplied by two other reputable fuse makers; one in Japan (PEC, the fuse supplier for Toyota and Honda) and one in Taiwan (Jenn Feng). There are a lot of good product data sheets and fuse educational information sheets on those websites. I have a crazy schedule, so I may not be able to reply to your comments or questions very quickly. youtu​.​be/nELwmfAOz_I

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Michael from Clinton

 

Mobile Technician
 

Hi John,

Very good demonstration. I am very curious if you could measure at what current the off-brand fuses blow.

Thank you for sharing.

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John from Ogden

 

Educator
 

Thank you! I plan on doing that, but I need to obtain a few more pieces of equipment to accurate control the current. There are specifications of percentage of over-current verses time. I want to try that and then use the frame rate of the camera as the timer.

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Bruce from Spring Hill

 

Technician
 

I did a test on some generic fuses. They were performance tool from the parts store, the numbers were not white. Put a 5 amp fuse with a current loop in place of a cooling fan fuse. It peaked over 50 amps and ran the cooling fan. I don't remember what the continuous amperage was. Put in a Bussman 5 amp fuse and it blew at 11 amps when I turned the fan on, cooling fan didn't move.

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Michael from Clinton

 

Mobile Technician
 

Bruce,

Cool idea for testing.

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James from Pike

 

Owner/Technician
 

Great info on something most, including myself, might not of ever considered. I will think better next time I restock my fuse bin.

Thank you!

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Bruce from Spring Hill

 

Technician
 

If you have any generic fuses, I would throw them away. If a 5 amp fuse will run a cooling fan. Will it blow when it needs to? Will a generic 30 amp fuse blow at all?

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Martin from Burnaby

 

Instructor
 

Great work as usual John. I was already aware of the GM bulletin about the Harbor freight Storehouse brand fuses from long ago and the fact that all fuses are not necessarily "engineered" to the same level. However, I've never bothered or had the time to go to the extent of testing, supported with measurements that you did here. Thank you for this.

I do advise my GM ASEP students to beware of "off-brand" fuses. Typically, their dealership employers source the preferred OEM brand, so replacement is likely not an issue unless the parts manager purchases through alternate suppliers. Being able to link to your Weber State YouTube channel to demonstrate that the cause of an extensive circuit failure may be attributed to an "economy" brand fuse, will be handy when delivering Electrical Diagnosis.

I'll relate a fuse experience of my own here. One day when preparing for class a year or so ago, I needed to install a blown fuse in an Acadia and grabbed a pack of Bussman fuses from our tool crib. When attempting to "pop" the fuse by simple connection across a charged battery, I discovered that I could just about arc weld with the blade and it took a significant time for a 15 amp fuse to blow, enough that the blade discoloured and eroded long before the actual fuse element section opened. While the erosion was more from "stroking" the fuse, the arc was quite significant and in comparison the OEM fuse didn't react as violently. It just opened as expected.

In wonderment at the unexpected result from a "quality" brand fuse, I repeated the test using original equipment fuses from the Acadia under hood electrical centre and those "popped" as expected. Again, the Bussman packaged fuses replicated the near welding experience and significant time to failure, which from recall, may have been 10-20 seconds. Knowing that there are some differences in tolerance within specifications, I didn't think too much of it other than being mindful of my preference to use the OEM fuses to restore circuit operation and making students aware that all fuses are not equal.

Even though my "accidental" testing was non-scientific at best, it had me wondering whether those Bussman packaged fuses were the authentic Bussman offerings, or some cheap clones in what appeared to be authentic packaging. Since just about anything can be cloned It would be interesting to know if you have spent any time inducing direct short circuit experiments to compare the fuses that you tested. I realize that there might be a slight time delay variance between products, but for a massive short induced directly across a battery to take such a significant time longer for the Bussman packaged fuses, seemed unacceptable, given the gauge of wiring that they were designed to protect.

It's always stuck in my mind, as being rather unexpected results from what I have always considered to be a quality brand product, but since my time is at a premium there isn't much time to conduct in-depth testing.

Thanks.

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John from Ogden

 

Educator
 

Thank you Martin. I have seen the same thing just plugging in a fuse in an underhand fuse block with the ignition turned on. It never occurred to me that it was my fuse quality. Thanks for the story and examples.

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Robby from New Market

 

Mobile Technician
 

Hi John,

Great demonstration! Thanks for posting this.

I almost caught a truck on fire one time by using one of those cheap fuses. The fuse for the DLC was blown, so I stuck in one of those fuses. That circuit was shorted to ground and it melted the plastic body of the fuse instead of "blowing" the fuse.

Another issue with a cheap fuse is the size of the blades. On the cheap fuses I've seen, the blade was about 0.005" smaller and was enough to cause a loose connection to the fuse box. 

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