99 GSX 12volt low light

[Dirtmod91]

I have owned this 99 GSX for sometime and runs great. When I first bought it had to put a rectifier in it for the charging issue. Having the same problem now with the 12v low light on and keeps blowing one of the fuses in the box where the starter relay is keeps blowing. Had a battery tester on it and battery reads 12.5 volts when off and when started drops it to 12.06 volts. Didnt know if there was a common problem or most likely a rect again. Is there a way to test it? Only thing different that happened two weeks ago a friend used it and got some water down in the hull. I always clean and flush it good and everything is in great shape inside. Didnt know if that water could of shorted something out.