My friends battery died on his evo8, so we swapped the battery. When we measure the reading at the new battery, it is 12.6 V (which is good) but when I start the car it drops to 12V and when I rev it up to 3000 RPM it stays at 12V.
I assume the problem was the alternator, so we went through the pain of replacing the alternator. After replacing the alternator, I pretty much have the same issue. It seems like it is not charging the battery. Is there a separate regulator or fuse I might of blown?
Any suggestions?

Thanks.

 

Interested in this as well.