MadaboutKitcars

I've been thinking about what value fuse to put in my fuselink?
Does anybody know what current range an ECU draws for the engine?

Maximum current draw scenario could be......

Engine running 5.0A??
Colling Fan on 12.0A
Heater on 3.0A?
Headlight m/beam 3.8A
Driving lights 3.8A
Sidelights x4 1.4A
Hazards on 6.4A
Fog and Reverse 2.9A

Which makes about 38 amps, so I reckon on a 40Amp fuse.

Comments appreciated,

Peter

The fuselink is only really to protect against a catastrophic failure - a short between the live side of the fusebox and the battery perhaps. My donor only had a fuselink between the separate ECU connection and the battery. The heavy wire to the fusebox was (and is) unfused.

I don't think 38 is anywhere near enough. If you use too small a fuse, believe it or not, they can actually wear out. The constant heating up and cooling gradually destroys the fuse link.

What normally decides the fuse rating is the size of the wire that it is feeding, not the actual load. You can look up the current rating for the wire and base the fuse on that.

Cheers

Robin

Thanks for the feedback Robin.
Point taken about catastrophic failure.
I want something that is not going to 'blow' through normal use or 'wear out' as you suggest but protect the car from a fire situation.

The bit of wire from the battery to the fuselink was re-used from the donor, so I don't know what wire size it is? (Physically its about 6mm diameter so my guess it's 80/0.4mm which is rated at 70amps)

The "40 amp" fuse I was thinking of using is spec'd at "40amp continuous/80amp fusing".
They also do 60A, 80A and 100A fuses in this size.

Perhaps 60amp continuous/120amp fusing would be a better compromise?

The 60amp being 150% of what I think I can draw under normal use with everything switched on.

I think that's what I would use. 40 is a bit on the low side.

Robin