I have a 2016.5 when I first received the SS I drove it infrequently and for short trips (no more than an hour). After a couple weeks the battery was completely dead. I had a power cable beside the driver seat, so I thought I would recharge through the cable. Nothing. I took off the battery panel and charged directly through the battery. I also found that the power cable was not attached at the positive lead. I ran a battery trickle charger periodically after that.
Then a year later my battery died. As I was charging through the power cord I noticed an arc. The power cable had no sheathing on it and it had worn through the insulation and was arcing on the seat frame. This had killed the battery. I next pulled the power cable, replaced it with a new one, and ran it through a proper sheath into the passenger compartment. This year i have not had the battery discharge, and I run the trickle charger monthly.