Fusible Link and the Starter Motor

[patrickt]

Originally Posted by fastd

Thanks for your post.
It helps a bit.

Not knowing how your car is wiring, it's a little difficult to understand when you write "on the positive cable after the starter solenoid."

I wrote a schematic, see pic below. First, you don't need a fusible link anywhere. But, if you insist on putting one on, only put it on the area marked in RED below. That is the area that has the potential for very high amperage should some sort of fault to ground occur. If you put a fusible link on the area marked in BLUE you will burn it up the first time your starter motor pulls amperage past the link's protection point. This is what I meant by saying "on the positive cable after the starter solenoid." Note that in my schematic I have a 50 amp circuit breaker protecting my system. Now, my alternator only puts out 60 amps tops, and my fans draw 30 amps under a hot air load, lights another 10, and if I turned everything I have on the car on I might be able to crest that 50 amp mark. What that would mean is that if the car was turned off I might be able to get that circuit breaker to pop off, but if the car is running all that load is being fed from the alternator, so the current through the circuit breaker is only a couple of amps at most to maintain the battery. Now, immediately after starting the car I might get 25 amps through that circuit breaker, for a short while, but never 50. And that breaker has never blown, ever. Now, suppose I had a 200 amp alternator and some sort of 100 amp load off the fuse box that only ran when the engine was on, maybe a Javelin missile launcher or something. In that case I still would not change the 50 amp circuit breaker because that load is served by the alternator. But if I wanted to shoot my missile when the engine was off, then I'd have to upgrade that CB to a higher amperage. Hope this helps you.