"What say you fit a 150 amp fuse in there following the advice of some around here and one day by accident try to crank while it's in gear" A good point I'll try and start my car in gear and measure it Yes many ways to do things, the example I gave was for a properly protected circuit by the book. You could just whack in a 200A fuse and it will still be fine. It's not like you ever have to crank the car for long. Edit: "Agreed one cable would be better as I suggested afterwards, you could run an 80amp fuse and a starter solenoid in parallel so you have the best of both worlds, nice safe minimal trip rating on the fuse and then no problem when cranking." Do you mean in parallel with the fuse to by pass it? You could but whats the point? There is nothing wrong with running a large fuse it's only there to protect the cable and if you select the right size cable there is no issues. What is one of those solenoids worth? I actually quite like this idea.
This didn't make any sense what I should of said is that the circuit will still be protected but the fuse will not blow as fast instead of < 0.4s (what a properly designed circuit should trip in) it might take 0.8s.
I have no firm idea of costs but it's all in the area of plausible I'm sure. Yes solenoid in parallel with the fuse so at all times except when cranking the cable is fused, as soon as you flick the key to start it's unfused and ready to blow shit up :rofl:
lol, I think it would still be quite a good setup as it will still be fused 99% of the time. Not trying to be a smart arse but considering all valid points, in regard to starting the car in gear. I measured a peak current of 265A (on my car) the highest that should be getting pulled by the starter and going by this graph using a 150A fuse it looks like you can pull 300A for about 3 seconds if you try starting your car in gear for that long in gear your an idiot and shouldn't own a car.. or you could just get a C/B if your worried about that.
From memory it should be 1.25x the short circuit current. And 1.2x the voltage. Could be other way around. That's for dc fuse and isolators in LV DC. Not sure if it applies to ELV DC but makes sence that it would be the same. The fact it's inrush current there are different types to handle the high inrush spike before blowing/ tripping. Hope this helps.
they arent fused at all.. a mate of mine was installing an amp under the passenger seat of his ve and screwed straight through the centre of the power cable and into the floor, it was in there for a couple of seconds before he realised and unscrewed it, I laughed cause out of all that floor space he just happened to pick that 15 mm where the power cable ran.
The Blue Sea 9012 ignition protected solenoid is around $180. A normal Ford style remote starter solenoid is around $30. I was thinking that the fuse is there not only to protect the cable/battery but also to reduce the possibility of a short starting a fire. I expect that the higher the rating of the fuse the higher the chance of a fire starting from a short that does not flow sufficient amps to trip/blow the fuse before starting a fire. I know that often people run the cable inside the car under the carpet. I guess it would just be safer and simpler run the cable under the car and keep the cable run inside the car to the bare minimum and away from anything flammable.
The fuse or circuit breaker provides short circuit and over current protection. The main reason is to prevent the cable from overheating this is what causes things to catch fire, red hot cables running through insulation, carpet etc. This is why you follow Ib<In<Iz (for short circuit protection) if the cable can carry more current than the fuse/circuit breakers tripping current it will never overheat. A short is a short it's going to pull a shit load of current through the cable. Larger the cable the larger the fault current, the larger the fault current the faster the circuit will trip. If in the unlikely event you have a situation where there is a fault somewhere and you are say drawing 149A through a 150A fuse and the fuse doesn't blow the worst that will happen is you will get a flat battery.
^ very well worded As I've said before, the fuse is there to protect the wire, not the other end of the wire is connected to. In terms of routing the wire, I found there's a cavity next to where the carpet is clipped into the door sill - this fits a 4g wire perfectly from memory, and partially protects it from damage.
I was thinking that the arcs from the short would start the fire not the cable overheating. The short could be caused by the cable insulation being damaged enough to cause arcs but not necessarily trip a 200 A circuit breaker before the fire has started.
Holden didn't even run a fuse in the VE as mentioned and they considered it safe... Run the cable properly and it will be fine or if you really feel it's necessary spend the extra $'s and put a solenoid in parallel with a smaller quick blowing fuse as Mungy suggested. I don't think it's worth the extra effort or cost personally.
For overcurrent the fuse will hold 1.2 rated current for 1 hour usually. Depends on the fuse used obviously. Considering that I should of used Ib<Inx1.25<Iz for cable selection (as indicated in the fuse graph@125% rated current working area) but not really worth worrying about as it never runs that high.
To add to this a circuit breaker can trip in milli seconds with short circuit current. So there are a few options. I'm signing out this has been done to death now.
A high impedence fault of 149A can definitely start a fire! That's true provided it's rated to clear SC current. DC fault currents are harder to clear and it's potentially as high as 2000A if the fault is near the battery. Fuses are much better in this respect - they always clear, which is why they are often used to back up breakers where the potential SC current is high.
"A high impeadence fault of 149A can definitely start a fire!" I agree sparks can start a fire happens all the time, but it wont be from a overheated cable. Faults normally get worse quickly though it's not going to stay at 149A for long. Impedeance refers to resistance in an AC cicruit "That's true provided it's rated to clear SC current. DC fault currents are harder to clear and it's potentially as high as 2000A if the fault is near the battery. Fuses are much better in this respect - they always clear, which is why they are often used to back up breakers where the potential SC current is high." Yes device selection is everything which is why I said device trip curves need to be looked at when choosing short circuit and over current protection. Pretty sure I said I would use a fuse multiple times, for simplicity and guaranteed operation. People wanted alternatives though.
Sorry gents, call it a whore/troll whatever but Im still at a loss why youd move the battery to the boot anyway????? What exactly do you hope to gain??? E
The only thing that i can think of is to tidy or make space in the engine bay and shorter cabling for big sound systems. The space in the engine bay seems like a good idea if you actually have something that needs to go there which I cant really think of anything at the moment. If I was to mount a battery in the boot I would be using a dual battery setup rather than just relocating it.
