Why does the battery have a cover?
 

All the other cars I have owned / drove had the battery in plain view without a box or a cover over it. The cover makes it so much harder if you need to start the car with cables from another car. My last car was a Kia Sephia which had a small battery , like the one we have in the Mazda 3, I replaced the Kia car battery with a big 25 amp one which is still going strong 7 years later.

12 views and 0 replies!! Is the question that stupid?

From a safety standpoint, the box helps keep the battery secure in case of a rollover.

If the battery leaks, the box helps contain corrosive liquid.

Older cars that don't have the battery in a box usually have a plastic cover over the top of the battery to keep the steel hood from being pushed onto the terminals causing a short circuit and possible fire.

But you'll notice that most manufacturers are putting trim covers over the engine, which I believe is mostly for cosmetic reasons. I can't imagine that a plastic shield over the valve cover can do much for noise reduction, but it's sure a PIA to remove when you need to do some mechanical work.

Thanks gfishe for your detailed reply. One more quick question: Does PIA stand for "Pain in the (body part)"?

asthetics

battery case
 

I battery cases are to help insulate the battery from engine heat on most new cars. On MS3 there is even a small cooling duct branched off from the intercooler ducting under the hood that blows into the battery case to provide active cooling to the battery.

Dry cell batteries would have been a lot more practical since they have no acid to spill and no need to check the battery liquid level.

True, but they would require more weight and space for the same energy content and would cost much more than lead acid. Lead acid batteries give huge power output for a short time in a small package, but they don't do well with a deep discharge. That is where the dry batteries of various types work better.

Thanks VAspeed3 for the info. You confirmed a fact that an uninterrupted power supply dealer told me: lead acid batteries give an initial string push but are not good at supplying longer term power. This is logical since most of their job is to start up the car when you turn the key.