He is saying that it wouldn't hurt. with 270a of generation, your 2nd batt would be okay but it depends also on how steady your amp drain is from your zx2500 (meaning what type of music you'll be listening to and for how long). Throwing another batt in there would give you some peace of mind though. The kinetik 1800 does somewhere around 80-85 amp-hours if I remember correctly, plus whatever you have under the hood.