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30 amp fuse failure


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After reading docc's original post on this I liked the idea he had and the way he did it so I went out and looked at the 30 fuse receptacle on my Greenie , even though it was still functioning  it was indeed burnt and starting to disintegrate ..so looking to head off a future issue I followed docc's link for the aircraft breaker mod and ordered one up, and then try to copy his install ....fun little project and satisfying as well!!IMG_4962.JPG

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After reading docc's original post on this I liked the idea he had and the way he did it so I went out and looked at the 30 fuse receptacle on my Greenie , even though it was still functioning  it was

Gentleman, I want to thank you all for all of your insight, education, and encouragement. Let's face it, what I'm posting isn't "rated" for anything.   *Entertainment Value Only*  

If the fuse looks ok check the connectors from the alternator to the reg/rec for overheating

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So I spent the winter and spring doing up the tenni as it needed some TLC.

I didn't touch electrics, it was mostly painting and fitting stainless where ever I could. I also fitted a new alloy tank.

Amazingly, it all worked when I stuck it all back together again, but the 30amp fuse has melted. Twice. Never done this before.

So, all things being equal, I’ve done something wrong. I though maybe I had painted over the ground behind the seat release keyhole, but it’s clean.

from what I’ve read above there’s a ground from the alternator via the regulator to the battery? Or did I get that wrong? Where would it be attached to?

any other thoughts?

electrics aren’t really my thing.....

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The regulator does ground back to the battery through the loom to one of the ring terminals. Cleaning and treating the rings and terminals is a good idea, as is adding a ground from the regulator case to the engine or timing cover.

Also, it occurs to me to suggest conditioning the battery with an approved charger and method (assuming it is an Odyssey PC545) rather than expecting our charging system to bring a needy battery up though that pitiful little fuse.

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It's probably in this thread somewhere, the reason for the 30 Amp fuse melting that is.

The cause as I see it is too much resistance in the clips holding the fuse, resistance causes heat at a current squared relationship and don't forget the current is pulsing, its not a steady DC but a pulsing DC, the peak is much higher than the average.

So saying my VII Sport welded a fuse into the holder but I was able to break it free and clean the socket up again. It never gave me another problem but I eventually replaced the regulator with a direct connect type.

Don't re-use a fuse that has overheated toss it and replace with a new one.

 

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On 11/2/2020 at 10:46 AM, docc said:

The regulator does ground back to the battery through the loom to one of the ring terminals. Cleaning and treating the rings and terminals is a good idea, as is adding a ground from the regulator case to the engine or timing cover.

Also, it occurs to me to suggest conditioning the battery with an approved charger and method (assuming it is an Odyssey PC545) rather than expecting our charging system to bring a needy battery up though that pitiful little fuse.

The problem is this wire has too much resistance, it has to carry the same 30+ Amps peak current as the Red positive wire from the battery back through the regulator to the other end of the stator winding.

The Red positive wire can afford a few Volts drop, the Voltage regulator takes care of that but the Black Negative cannot afford any Voltage drop, half a Volt there is taken directly from the battery Voltage Reference.

Remember the voltage regulator is hanging on a bracket that's not even grounded properly, just accidentally grounded where the paint scrubbed off. A short wire from the regulator case to a timing cover screw is like a massive cable through the mass of the engine/gearbox to the fat battery ground.

It's only the earlier Ducati Energia regulators that need grounding, the later bikes have a direct connected regulator as shown, item (22)

2004_V11_Sport_Catalytic.gif

 

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Thanks for all this, I’m still a bit in the dark to be honest. 
it might be only a coincidence, but I don’t really get why painting the engine casing and a few other bits would suddenly trigger the fuse to melt. Twice.

the fuse holder is now damaged beyond repair where the 30a fuse is held so I’ll have to separate the 30a fuse away from the original holder. I like the CB idea, but probably won’t be able to get hold of one.
(I fly 787s, and we don’t even have access to them in the cockpit anymore!)

I thought maybe I’d find a damaged or disconnected wire somewhere due to my clumsiness, but nothing obvious so far.

may be time to call in a professional.....

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No , now is the time to check , clean and make all ground connections PERFECT . Grease , shakeproof washers , the works . IDK if this is the culprit , but it is a place to start .  With the terminals done , you need to trim back to good wire and install a new device .

What do you have access to ? The CB is the premium way to go ! 

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+1 on gstallons advice, no matter what direction you go with this.  Seems if you have to replace the fuse connectors anyway, the CB is the way to go. The 30 amp Tyco looks available:

https://www.aircraftspruce.com/catalog/elpages/pbcircuitbrkr.php

I still wonder if the Tenni's battery had gone rather flat over a long time and the charging system had to way overheat those tiny fuse connections to bring it up, along with the various connecting points having gotten corrosive. In other words, that there is nothing actually broken, pinched, shorted or really "wrong" after the reassembly.

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