So I went to get into my car after a long day at work today to find that my battery was 100% drained... took my multimeter to it to find it was pumping a massive 4v... I jumped my car with help from a friend and the car idled fine and I started driving home... got about 20 seconds down the road when it started.

My wipers came on at full speed and my engine shut off and some of my idiot lights came on. My car blew the 80A fuse... again... I replaced it and got another jump to get another 20 seconds down the road for the new 80A fuse to just blow again.

I left it for the night but found that this only occurs while driving not idling. What I think is causing it may have to do with the alternator. I did the 130A Taurus alternator swap. Is it possible that its overcharging? I didnt upgrade the B-post wires like some have suggested.(I used the stock wire with a larger ring terminal) The B post isnt grounding as it is covered by a rubber boot and has no contact with anything.

 

I would think that because the alternator is pushing out more than 100 amps, you would also have to replace the fuse accordingly...correct?

 

yes, very easy to check, put a voltmeter on the B+, and see. a stock Mazda alternator will be 13.5-14v, a more modern alternator might be higher. over 15v is getting too high

if the wire was too small, it would have melted before the fuse blew, which is the point of the fuse. you may have a short somewhere, as the car shouldn't need 80a just to cruise down the street

 

the alternator was putting out 14.4 at idle last I checked.

 

If the problem occurs when driving (and not idling) then you need to check the output during that time.

 

Sounds like your regulator is toast. Check voltage while holding a higher rpm

 

well... I replaced the Main fuse and the engine fuse again and redid the ring terminal attached to the B post and turned on the car and checked the voltage while holding a higher rpm and it never exceeded 15.5ish. I drove the car home without any issues but idk maybe the B post was the problem.