The "deep cycle" batteries are designed to permit frequent charging/discharging cycles like what would happen if you had a high end audio and/or video system and you wanted to be able to operate it without the vehicle running for long periods of time. You will frequently see these used in show cars.
A "starting" battery is NOT designed to handle regular cycles, but rather to hold enough charge to start the car. Once the car is started, the alternator provides the power for the a/v system and accessories so the battery charges itself back up and then doesn't really do anything until you go to start the car up again.
What type would be better depends on how often you start your VX and how long you want to play your a/v with the vehicle not running.
Etlsport - What you probably have in your VX right now is a starting battery. If you can start the vehicle, and run all of your accessories with the headlights on and you don't see any dimming of the headlights, you're fine. If you DO have signficant dimming, it's your alternator you need to look at possibly upgrading.
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