discharge/overcharge?

trailbeast, went back out and jumped a 10 gauge wire from the battery to alt battery post and no change. it seems like a voltage regulator problem to me but i don't understand why the amp gauge shows discharge while the system is clearly overcharging 15v at idle with no lights on just now when i checked it before jumping it. is there anyway to test the regulator, i don't mind to buy one at all if i need it, just hate to waste money on it or if something is wrong and messes up a new one too since i have two of them doing the same thing right now.