100 Amp fuse move

[Belle427]

I'm considering moving the one that sits under the car on the engine mount to near the alternator so its more accessible.
Can anyone see a problem with this, it will sit probably on the alternator body itself.
The way I see it this fuse protects the alternator anyway so being closer to it is a bonus.

[bobfather]

Not the answer you seek but I must ask why. This fuse blows mostly because the harsh environment weakens the foil fuse causing it to blow at a lower peek current. The answer as I see it is to replace it with a capsulated fuse which will be unaffected by the environment. Further, as many owners have done, it is reasonable to increase the rating of the fuse to 125A to decrease the likelihood of blowing due to spike current

£3 from Racetech, see3 here

[Belle427]

I have a midi fuse fitted but usually the fuse should be as close to its source as possible.

[bobfather]

Belle427 said:

I have a midi fuse fitted but usually the fuse should be as close to its source as possible.

I see your point however this particular cable has a source at both ends. The battery end being the more dangerous. The fuse cannot be fitted at the battery because the starter motor requires an un-fused feed. I think the chassis fuse protects the circuit from shorting the battery, not the alternator. Therefore the fuse needs to be where the battery cable splits to the starter motor

[TwinKam]

bobfather said:

Belle427 said:

I have a midi fuse fitted but usually the fuse should be as close to its source as possible.

I see your point however this particular cable has a source at both ends. The battery end being the more dangerous. The fuse cannot be fitted at the battery because the starter motor requires an un-fused feed. I think the chassis fuse protects the circuit from shorting the battery, not the alternator. Therefore the fuse needs to be where the battery cable splits to the starter motor

Good point, well made. This also explains why the Cerbera one is in such an awkward place.

[QBee]

I fitted a midi fuse back in 2012 after my first metal strip fuse blew in the first 4 weeks of ownership.
The midi fuse blew on a track day in September 2013, causing me to spin, stall and have to be recovered.
Replaced that with a metal strip fuse purely because it was a Sunday and that was all i could get.
30,000 miles and 4.5 years on, and it is still going strong.

[ChimpOnGas]

Belle427 said:

I have a midi fuse fitted but usually the fuse should be as close to its source as possible.

This is correct, and your point about making it more accessible seems logical too, ignore the doubters and just do it, the idea makes perfect sense to me.

BTW I switched to a midi fuse back in 2010, I just fitted it under the engine in the tradition place but I did replace the fuse holder too for good measure. Since then I've been promoting the midi fuse idea to others, eight years later I'm still running the same fuse with no issues whatsoever so I kind of view it as a non issue these days.

The original strip fuse used by TVR on the other hand is physically weak and fracture prone, so it should be replaced with the far stronger midi type if you haven't done so already.

Dave.

[Penelope Stopit]

Belle427 said:

I'm considering moving the one that sits under the car on the engine mount to near the alternator so its more accessible.
Can anyone see a problem with this, it will sit probably on the alternator body itself.
The way I see it this fuse protects the alternator anyway so being closer to it is a bonus.

The fuse doesn't protect the alternator it protects the supply to the alternator but as a bonus it will blow if the alternator main positive shorts to earth/ground/return
If you are confident that the alternator supply cable is of a good safe run, you could fit a 100 AMP fuse close to the alternator just in case the alternator positive post ever shorted out although they rarely do

Bear in mind the starter motor cable isn't fused

[Belle427]

I have a new piece of cable to run from alternator to starter, it will run through a protective conduit.

[ChimpOnGas]

Belle427 said:

I have a new piece of cable to run from alternator to starter, it will run through a protective conduit.

This is also a good idea, TVR used rather inappropriately thin gauge starter/charge/battery cables and after all these years refreshing them with something newer and of a heavier gauge is good practice.

Six years ago I addressed this weakness on my Chimaera; what I pulled out in the process was string thin, corroded, and rather crispy in places. I also added an additional earth cable from the block direct to the negative battery terminal for good measure.

You can read about it here:

https://www.pistonheads.com/gassing/topic.asp?h=0&...

This and correcting the true origins of the so called 'Hot Start' fault completely resolved any sketchy and unreliable starting issues the car had started to present, and no so called 'Hot Start' kit was needed.... which is just a relay anyway

To this day the car spins over like a top even when hot restarting on the most brutally scorching day in the South of France where I've seen ambient temps rise to over 100 degrees Fahrenheit.

[spikep]

I moved mine to by the battery which is now behind the drivers seat.