Lithium battery questions

[TuxedoCartman]

So, it turns out I'm being way more anal about weight on this car than I thought I'd be when I purchased it. Not NA Miata-owner crazy, but still pretty obsessive. And since I'm looking at adding a chunk of weight in the form of a supercharger, it got me to looking at areas under the hood to trim some unnecessary pounds.

First place I figured to start was with the battery. Now, I'll admit: I'm blown away at the options that have popped up since I had my last tuner car, and I'm especially intrigued by lithium-ion car batteries they have available now. Sure, they're expensive as fuck, but they also weigh next to nothing (one I saw had a claimed weight of only three pounds?!) Unfortunately, the only experience I have with lithium-ion batteries, however, is with laptops and various low-voltage hobby electronics. And my experiences there were, "Do not charge li-ion incorrectly, or it'll explode. Do not damage li-ion, or it'll explode. Do not subject li-ion to vibrations or movement, or it'll explode. Do not stare too long at li-ion, or it'll explode and kill your whole family..."

So my question is this (sorry, I ramble): what do I need to know about switching from a normal acid battery to a lithium-ion battery in my car? Do I have to change out my alternator, or hook the battery up to its own charger at night, or anything like that?

Any help or insight would be useful. Thanks!

[paaji]

Can't answer the above questions, but as an alternative take a look at the Lithium Iron (LiFePO4) batteries. All of the benefits of lithium ion, but none of the family killing explosiveness.

[Ryephile]

+1 you want a LiFePO4 battery, not a lithium-ion. Lithium-Iron-Phosphate are drop-in replacements for Lead-Acid. Just be mindful that they cannot be run dead; if you leave the car stored for winter you need to unplug the battery or keep it on a Battery Tender that has a constant voltage function to keep from over-charging the cells.