Big 3 upgrade and HO Alt

[Jrwill]

Here's my question. I'm upgrading from my stock 85a alt to a new high output 150amp one. While I do this work I figured I would do the big 3 upgrade a well. My question is from the alt + to batt + what size inline fuse should I use? 100a? Or bigger and match the max output of the new alt at 150a fuse?

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[keep_hope_alive Premium Member]

depends if you are keeping the factory wiring as well. if so, you have a parallel path and current will be split (not equally, but based on wire resistance). if that is the case, the 100A fuse is probably fine.

you're fusing at the battery to protect the battery. i'd go with a 150A fuse as close to the battery terminal as possible (assuming you are using good quality 4awg or larger). you don't want to replace that fuse, it's just there for protection due to a short.

 

[keep_hope_alive Premium Member]

fyi - for a good how-to on the alt to battery wire, check out this thread:

http://forum.sounddomain.com/ubbthreads.php?ubb=showflat&Number=1804618&page=1#Post1804618

in my case, i had parallel paths and a 100A fuse was fine on the new wire.