Lightweight lithium ion battery...

100%! But you need a high quality brand, and I never charge it unattended.

I did on one of my cars. That was the least expensive weight reduction on the car I did. (cost per pound)

Sometimes it's not about the weight, but where the weight is in the car. The smaller package of the LI battery allowed me to put the battery in low and in the rear cargo bin.

XS Power XV series, IIRC

Stop ordering the double cheeseburger for lunch and you will drop 35 pounds while also saving yourself $500

Then you take the $500 you saved from the cheeseburgers and buy the Li battery. Now you've dropped 70 lbs without spending anything

I had a friend pull this out of a very high dollar Super Stocker while warming up at the track. He has gone back to lead acid.

What brand?

No. It's going towards a dual fogger

He said it was a Lithium Pro battery

Yeah, I could stand to drop about 40 lubs... getting old sucks

"Thermal runaway" with a lithium ion battery can be pretty scary. I don't know how commonly that type of battery design has issues in automotive applications, but it does have me questioning whether that's the direction I want to go

You can do it...I dropped 70lbs after a couple years ago. I definitely feel better.

As for a Lithium battery be very careful what you buy. Charging can be an issue, and running an alternator can be as well. All of them have a max voltage they can tolerate and need to take that into account with an alternator. We have had very good luck with Go Lithium batteries and alternators with regulators turned down to just under the for the battery

A good lithium ion battery supposedly has a built-in battery management system that will prevent the conditions that cause the battery to catch on fire. Of course that's no guarantee that there will never be a problem. But that's why it's a good idea for us to keep track of what brand of batteries have the fire. I have been using anti-gravity batteries with no problem and they claim to have a superior battery management system, such that you can use the cars alternator to charge it for street driving. I have done just that on drag week.

Losing 35lbs, don't think I would feel good at under 130 so gonna pass on that one

I thought about a Braille battery for the new project, but decided to move the existing lead-acid unit to the trunk and put the weight to good use.
But adding a switch for it doesn't bug me.

As for driver weight: I've always been skinny - usually 160 lbs - so it's always seemed a curiosity to me when big round guys are worrying about car weight.
I'm not being judgemental, it's just something I've never personally had, though my younger brother did get the "weight gene".
But everyone I've known who's returned to a more proportionate weight has felt & performed better.

I used to feel the need to carry weight around for my job, not necessarily round But upon being done I was headed there. I am no longer a military contractor and just felt there was no reason to be as big a guy. Plus I am old now I still go 220 but I am 6'3" still

IMO Lithium Pros is one to avoid. I have seen to many who have had issues with them including me. Not fire issues with it just charging, battery life an unexpected failure as well as poor customer service.

I use antigravity brand battery , Weighs 8 lbs and it is a group 24 size case. Battey and charger was $425 2 years ago. It runs my fan in between rounds with no issues . I like it and would buy another.

YEP. Spent more than that on less.