100A midi fuse - how bomb-proof?
Discussion
Hi...
I suffered my first 100A fuse failure on the way home last week.
The first thing I noticed was a big hesitation when I dropped down a gear to accelerate hard. Then about 30 minutes later I noticed that the oil pressure and the temperature were reading slightly low. By this point I knew I had an electrical failure, and a few minutes later I stopped, with no electrics at all.
I tested at the back of the alternator and found no battery voltage with the engine off, but I got some volts with the engine running (hard to get the probes firmly onto the terminals).
I’ve just replaced the 100A fuse with a midi fuse, and sure enough the strip fuse broke into two pieces as I took it out.
My question is, how much more robust is a midi fuse? Has anyone fitted one and still had a failure?
I know lots of people treat the strip fuse as a routine service replacement, but what about the midi fuse? Can I “fit and forget”, or should I still replace it routinely?
I suffered my first 100A fuse failure on the way home last week.
The first thing I noticed was a big hesitation when I dropped down a gear to accelerate hard. Then about 30 minutes later I noticed that the oil pressure and the temperature were reading slightly low. By this point I knew I had an electrical failure, and a few minutes later I stopped, with no electrics at all.
I tested at the back of the alternator and found no battery voltage with the engine off, but I got some volts with the engine running (hard to get the probes firmly onto the terminals).
I’ve just replaced the 100A fuse with a midi fuse, and sure enough the strip fuse broke into two pieces as I took it out.
My question is, how much more robust is a midi fuse? Has anyone fitted one and still had a failure?
I know lots of people treat the strip fuse as a routine service replacement, but what about the midi fuse? Can I “fit and forget”, or should I still replace it routinely?
I have had one fail, about a year after i replaced the flat type one with the midi one after seeing a Chimpongas thread about it.
No idea why it failed, no symptoms until the car suddenly stalled as I downshifted for a corner, which resulted in a spin.
As luck would have it I was on an airfield trackday at the time, so only demolished a few cones.
I replaced it with a strip fuse, as it was the only one I could get at such short notice, and that fuse is still in the car 7 years and 40,000 miles later.
So they are not infallible - but as Zener said, there must have been a reason.
I had to replace the alternator a year later, when it died on me and the ignition warning light came on.
The car will do 45 miles home on battery, I can report.
Draw your own conclusion.
No idea why it failed, no symptoms until the car suddenly stalled as I downshifted for a corner, which resulted in a spin.
As luck would have it I was on an airfield trackday at the time, so only demolished a few cones.
I replaced it with a strip fuse, as it was the only one I could get at such short notice, and that fuse is still in the car 7 years and 40,000 miles later.
So they are not infallible - but as Zener said, there must have been a reason.
I had to replace the alternator a year later, when it died on me and the ignition warning light came on.
The car will do 45 miles home on battery, I can report.
Draw your own conclusion.
and some generic ones are appalling quality , dont get me started on poor blade fuses Early Chims don't have this fuse. What useful purpose does it serve? I suspect that it is only there to stop someone trying to jump start by connecting to the back of the alternator when they can't be bothered to find the battery.
From what I have seen on here they cause more trouble than they are worth. Has anyone ever heard of one blowing for a good reason? If my Chim had one fitted I know what I would do... get rid of it! (just my opinion).
From what I have seen on here they cause more trouble than they are worth. Has anyone ever heard of one blowing for a good reason? If my Chim had one fitted I know what I would do... get rid of it! (just my opinion).
Jon100p said:
Early Chims don't have this fuse. What useful purpose does it serve? I suspect that it is only there to stop someone trying to jump start by connecting to the back of the alternator when they can't be bothered to find the battery.
From what I have seen on here they cause more trouble than they are worth. Has anyone ever heard of one blowing for a good reason? If my Chim had one fitted I know what I would do... get rid of it! (just my opinion).
Isn’t it supposedly there to stop alternator surges?From what I have seen on here they cause more trouble than they are worth. Has anyone ever heard of one blowing for a good reason? If my Chim had one fitted I know what I would do... get rid of it! (just my opinion).
I chose to remove mine for the reasons you suggest, I see little point in it.
I replaced the cable when I did it and enclosed it in a protective conduit.
Jon100p said:
Early Chims don't have this fuse. What useful purpose does it serve? I suspect that it is only there to stop someone trying to jump start by connecting to the back of the alternator when they can't be bothered to find the battery.
From what I have seen on here they cause more trouble than they are worth. Has anyone ever heard of one blowing for a good reason? If my Chim had one fitted I know what I would do... get rid of it! (just my opinion).
Was going to post the very same comments yesterday but didn't bother, it's difficult convincing people to ditch a big fuseFrom what I have seen on here they cause more trouble than they are worth. Has anyone ever heard of one blowing for a good reason? If my Chim had one fitted I know what I would do... get rid of it! (just my opinion).
The 100 Amp fuse will protect the alternator supply
As long as the supply is in decent sleeving and of a safe run to the alternator.......................bin the fuse
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