I have the factory twin battery set up with 3 way switch, the Sony blue tooth stereo, with the Kicker speakers. I thought the Wet sound sub woofer addition was too expensive at the time I ordered the boat, so I did my own thing. Bought a small footprint Kenwood powered sub woofer ... the wiring on the Kenwood is very basic and simple / plug and play, as the Sony has all the output and input jacks hanging off the unit mounted inside the helm. Sounds good, right. Well, with the ESP package the whole bottom of the boat is covered in aluminum sheets .... no way to run power to the amp from the battery without drilling holes in the floor and aluminum. I'm not willing to do that to a new boat. So, I bought an Optima deep cycle sealed marine gel battery. This weekend, it should be a simple install now. I'll put the Optima gel battery in the helm and connect the Kenwood power cable direct to the Optima battery. I have a small Battery Tender Jr. that will easily keep the battery charged after each use. I did a similar set up a few years ago on a fiberglass runabout that only had one starting battery. I did the same free standing battery to this boat and the stereo with the same brand sub would run for hours with no problem. I forgot, this Kenwood sub is only 150 watts as advertised, and most likely less actual watts, but the sound is a big improvement over just the typical Kicker style speakers....and I don't play it really loud either. Just food for thought, inexpensive and functional.