Batteries..
 

My lithium ion batteries weigh a fraction of my cell type batteries in my cordless tools. Why no lithium ion car batteries yet?? Maybe 4-5 lbs max?

One word answer: Money. Lithium batteries are expensive to make, have to be recycled totally separately from lead acid units (trace amounts of lithium contamination in lead make the lead useless for making new batteries, and lead acid battery manufacturers have by law a mandated candle to grave responsibility to recover and reuse the lead, so they do not want to be required to set up a second system to handle lithium), and they require a unique charging profile to bring them back up. So to go mainstream, they need their own recycling and recovery systems, plus alternators and voltage regulators designed specifically for them. And they are still going to cost a lot more, like several times more, than a lead acid battery.

From a bang for the buck perspective, lead acid is pretty hard to beat.

I can speak for motorcycles, but not cars. I have lithium batteries in both of my bikes. 1 1/2 lbs. (instead of 8-10), they hold a charge for up to 1 year without a trickle charger, no special charger needed (1/2 hours on 6 amps and they are fully charged), they can be mounted in any position and don't out-gas hydrogen, and they work fine with the stock alternator and voltage regulator. However, they are about twice to three times the price of a lead-acid motorcycle battery, and they work poorly CCA) in temperatures below freezing. Do a search, I bet they are out there.

I am a registered batteryholic.

I currently have:
7 yr old stock Bosch battery that still holds a charge 40 lbs $120ish
Deka motorsport AGM battery- 17 lbs $89
Odyssey PC680 AGM battery- 15 lbs $114
Shorai LFX36 Lithium Iron battery- 5 lbs- $300

All batteries start the car easily. The lead acid Bosch is the least vulnerable to overcharging and has by far the best reserve power. The 2 AGM are in the middle with the Deka offering better starting amps. The Shorai requires special care and feeding with a proprietary charging system. It is very light and works well. Pick your poison.

35 lb difference is huge. That's more than the rear cat delete savings or about what the spare weighs! Seems worth the cost.

There are Li-on car batteries. But they're just... so... damned... expensive. :barf:

Porsche Lithium Ion Battery

I think the Shorai LI is worth the cost but if you don't pay attention to the unique charging requirements you can brick it. We run Time Trials in PCA and there are very specific things we can/cannot do in our class. A LW battery is free of penalty points so it is a slam dunk for us. I don't recommend this for the avg daily driver due to the very limited AHs though.

damnit didnt see deserion's post.

Would seem silly to me to spend big bucks to cut the weight of the battery by 30 lbs while I'm still carrying an extra 50. I would be further ahead to just cut back on the cheeseburgers.

They always say the best way to make a car go faster starts with the driver...

But try to loose that 30 lbs- it's much easier to spend money and get the job done NOW! :D
(Still working to loose lb #2)

I've seen 12V lithium polymer (LiPo or LiFePO4) (same as the Porsche batterry) under $500 before. That porsche battery is the similar size of RC LiPo battery packs but I'm not sure why they charge so much, perhaps the "gold crest" allow them to.... iono!?!

There's a lot RC people use their LiPo battery to jump start cars, youtube it!

BTW, there are two types of lithium battery people use for high discharge current, LMO and LiFePO4. All powertool and e-bike maker use LMO batteries but for car and motorbike, they should all use LiFePO4. Supposely LiFePO4 (A123 battery company) claim it can operate anywhere human are active.... something like -50degF (don't quote me on that).

thinking about going with an optima. A lot of talk about the odessy batteries but when i look they are for motorcycles? these are much lighter than stock. Can anyone enlighten me on which one they are using for their boxster? I dont drive mine in the winter, I live in RI. Its basically a summer car used for joy riding on the weekends.

These are all good lightweight choices:

Deka motorsport AGM battery- 17 lbs $89
Odyssey PC680 AGM battery- 15 lbs $114
Shorai LFX36 Lithium Iron battery- 5 lbs- $300

You will have to fabricate a solid mount or battery strap and I recommend keeping an AGM on a battery maintainer designed to work with AGM batteries if the car sits for longer than 1 week. Porsche electronics draw current even when the car is off.

If you're thinking of an Optima battery you want the Optima 34R since this reverses the battery plus and minus posts allowing it to easily connect with the Boxster setup. However, the Optima battery not as wide as the standard Porsche battery and you will have to either make or purchase an adaptor plate allowing the Optima to be secured by the mounting bolt located in the bottom of the battery tray. Great batteries though.

ok so the odyssey P680 is basically designed for motorcycles. Are there adapters so the Boxster battery clamps can clamp to this battery? Are those what the "L" adapters are for?