Alternator

I ariganly had quistion about alternator, I did what you sais, load test it shows battery is good but not chargeing I took it to auto zone they said alt is chargeing im thinking voltage regulator on that same plug there is a little battery looking thing whith 1 wire is that a diode its on the voltage regulator plug its about a aa batery size and a little farther over on the fender passenger side theres anouther little thing it has 4 wires but its plastic and a little larger could 1 of these be bad