The 550 Car Battery

Braille Battery is going to start selling an aftermarket car battery which uses the lithium ion chemistry instead of lead acid.  It will weigh only about 6lbs, and is claimed to hold its charge, maintain voltage under load, and recharge better than a lead acid battery.  

But this cutting edge battery will cost you: MSRP is $550, or about 5x a normal lead acid battery.

You can read the PR here.