Lithium-Ion battery?
 

Has anyone swapped their lead acid out for lithium-ion?

LIGHTWEIGHT Because of 3x higher specific energy and energy density numbers, Lithium batteries are small & light.
SUPER DEEP CYCLING Depending on discharge depth, a Lithium battery can do 5x as many cycles as lead acid. It can handle 80% depth of discharge (DOD) while lead acid handles 50%. If replacing a lead acid battery under two years old due to deep-cycling damage, you'll save in the long run switching to Lithium-ion.
FAST RECHARGE Lithium batteries can accept charge current up to 5x faster than lead acid batteries. Charge efficiency is about 75% for lead acid compared to 97% for Lithium, which means less recharge time and alternator strain.

No need for venting, fully sealed!

Even at double the cost I'm considering it.

Interesting, :popcorn:

LION - as least in cordless tools....don't work for sh1t in the cold though.

I have been running AGM and went up a larger size

I agree on the cold weather factor. Try using a cordless drill when it's been sitting in a garage overnight in the freezing cold.

I have drills with the lithium batteries and if I leave them in the work van over night in -20c weather they will be totally dead untill they warm up , also with the lithium battery they keep full charge all the time and then they completely dye with no sign of getting week. In my opinion I would stay away from lithium in a vehicle ,thats my 2 cents.

Doesn't Tesla Motors uses lithium-ion battery packs for their cars?

Yes

My X spends almost all its time in TX and FL so there's not much cold weather operation. Over 175k miles and has NEVER turned a wheel on snow/slush/ice. The X is in a warm garage and the Accord slogs thru the crappy roads.

Hmmmm. If it's not a better alternative right now, give it a year and there will be this type of OEM and after market battery available everywhere. Only a matter of time. This is simply better technology.

Now how many people drive Teslas in freezing temps and snow?

B, probably quite a few. A $100,000 car is quite common nowadays.