Battery Relocation

Why would I move my battery to the trunk?  

The biggest reason is for an even weight distribution to all four corners.  You might say the battery won't make a huge difference, but anything can help.

The average car battery weights between 30-40lbs.  In the C30, that battery is located above the driver's side front axle.  That is a lot of extra weight along the left side of the car: the driver, the steering wheel, the pedals, the gauges, even the transmission sits slightly towards the left.  By moving the battery closer to the back right axle, the weight is more evenly distributed front to back and side to side.  Yes, that is less weight pushing the front drive wheels towards the ground, but it helps create a more balanced car while zipping through the turns.

Another reason to relocate the battery is to extend its life.  Most people get 3-6 years before the battery is sufficiently dead.  Temperature, alternator efficiency, sound system, and even phone chargers all have a play in the battery's ultimate life span.  But one of the biggest battery killers is the constant heat of the engine bay. Especially in a car with a high pressure turbo, a summer day could see 200°F around the engine block.  Even though the cabin gets warm, it is a climate controlled environment that can extend battery life up to 10 years or longer.

But is it safe to have the battery in the cabin?  

Many performance cars have trunk batteries and many enthusiasts relocate their batteries as well.  The main concern with a battery in the cabin is the hydrogen gasses emitted from the cells, which is why a battery in the car should be fully enclosed with proper ventilation.
Technology has improved a lot in recent years, but there is always a risk when dealing with a wet-cell battery.

For my battery relocation, I cut a rectangular hole in the rear shelf and bolted in a Walmart battery box.  While this is not a sealed container, the Ultima Redtop battery has a special sealed case.  On top of the battery are two small vent ports; these only vents under extreme circumstances.  To play things safe, I connected a rubber hose to those vents and routed them through the floor, outside of the car.

• The power wire was run through the cabin with a fuse 12" from the battery; if anything were to happen, there would not be a live wire running the length of the car.
• The area around one of the trunk bolts was ground down (pun intended) to use for my battery ground.

Trunk battery box

Admittedly, the box is a bit bulky. If the shelf extended level with the trunk, the battery could be completely hidden, but this suffices for my needs and still provides easy access to the battery.

Up front, it was just a matter of reconnecting various wires to the new power source and removing the unnecessary brackets and casings. 

Engine bay with battery removed

I have a few plans to utilize the extra space, but that is another project for another day.  

For now...

There's so much room for activities!