Alternator oR Battery

[209er]

First is there any way I can tell how many amps my alternator puts out. What should i get first to stop my voltage. I can either get my xs batt or a 180 amp alt from dc.Ill be pushing around 1500 to 1800 watts on my 99 tl(w/navi)

[DJ 92]

The voltage drop is innitally from the alternator not putting out enough amps so id go with a alternator but thats not gonna do much without a battery

[08tahoe]

first go with the biggest xs batt you can fit up front and do the big 3 and then go from there