you need to run one 30 amp relay for each fan and put the fuse between the power supply for relay and relay.should do same on fuse.have each fan relay have it's own fuse[30 amp]another thing is once you do your fans this way and you blow one one fan fuse then that fan could be getting weak and causing more amp draw causing fuse to blow..fans do go bad in time..if they start blowing fuses then that is a good sign that fan is bad..the bigger alternator will have no effect on fuses blowing.on some street cars i've built for myself and others i've gone frome stock 30 amp alternators too 110 amp alternators and never blowed any fuses..alternator only charges the battery..