I’m still conflicted about how to interpret this part:
“The fuse is "rated" at approx 66% of its load. This means that a 10Amp fuse will not get hot enough to melt until more than 13Amps tries to get through it.
The fuse is also tolerant of a spike in power which means it can cope with 13A but not for long (a second or three) but it will melt pretty quickly is 20Amps went through it.”
Can a 10A fuse “handle” a load between 10-13A over time?
Yes a 10A fuse can handle more than 10A over time but will get hot.
As the load goes over 13A it will most likely get hot enough to melt and the circuit will be broken.
Getting hot and cold (turned on and off) over time will also weaken the fuse, as the metal expands and contracts, eventually it will crack.
A fuse will last longer if the current does not exceed its rated value and progressively less time as the current increases.
Or a real world example; what happens if K1LL3M turns on the LED-bar with the ignition off ?
So, if the battery is fully charged (lets say 12.5V) then the current will be 25.24 Amps.
The 25A fuse and cables will be fine.
As the battery discharges and the voltage falls, to say 12V, he will draw 26.33 Amps.
The fuse will warm up and expand a little, but still not fail.
After a while the battery will discharge a little more and when it gets to 11.5V the lamp will draw around 27.5A at this point, the fuse will still be 'continuous' and will be a tad warmer...
Depending on what else was 'on' in the car the battery would start to get damaged at this point.
I don't have a Grenny so don't know for sure what battery is installed so don't know the C number (dishcharge rating).
Peukerts law comes into effect in that the faster that you discharge a lead acid battery of any type, the less energy you can get out of it.
This means the voltage will drop faster and the current drain will increase, so with around 9.5V in the battery the fuse will get hot enough to melt.
This is all a bit extreme though.
In real terms then, only the pedants/lawyers will be concerned that a greater than rated load was being applied 'if' there was any related warranty or insurance claim requested.
These lights won't pop the fuse, won't set fire to the cables, so shouldn't be a problem.
