Why do R33s have a 10a Alt S fuse ?

[discopotato03]

Long story short , I asked KB electronics to make an alternator voltage booster fuse replacement .

They want to know why this fuse is 10a as in what else is wired into the alternator sense circuit that needs it .

All I know is that this fuse is in the back fuse box near the battery .

Any help appreciated , cheers Adrian . 

[GTSBoy]

Fuses protect the wires, not the equipment connected to the wires. Hence, you size the fuse to the wire's capacity. 10A makes sense.

[discopotato03]

Fair enough , I'll get back to Leigh at HKB electronics and mention this .

BTW I've just fitted the 140a LS1 Mitsy alternator and the voltage at idle can still fall below 14v , I believe this is due to alternator voltage compensation at running temps . I've watched the idle voltage drop and rise sitting at lights and driving along in warm weather .

Ideally I want about 14.7v cold and around 14.3 at running temp . Its actually interesting to read what's happened over the last 20 years with alternator voltage regulation . Voltage deliberately reduced to drop idle load emissions and fuel consumption . One mob reckons some cars are deliberately regulated low which reduces battery voltage and then alternator voltage ramped up to around 15v under extended braking to - emulate a regen brake .

Anyway I want what keep my battery right up and 14+ into coils injectors and fuel pumps won't hurt either .

Thanks and cheers from Adrian .    

[GTSBoy]

Nah. Don't bother. At idle it doesn't need to be making max volts and charging like a mofo. If it's charging at all at idle, that's enough. What matters it what it's doing when its under load.