Extra Battery

[rleetsc]

Now that I have added a headunit and the LEDs to my cart I am deciding between purchasing an extra battery or a voltage reducer. I am kind of leaning toward the battery option but the issue is where to put it more than anything. The only location on my cart to put another battery is the bag well which I already have plans for and may have to modify a bit to make space for another battery. My question to you guys is:

1. Which would you recommend (Battery for Reducer)?
2. If a Reducer, which one? / If a battery, which one?

Note: Battery wise I am looking toward a blue or yellow top Optima.

Thanks!