Ohm (YC S15) is a smarter, lighter car battery that works with your existing car

This price has come down by 66% in just a couple of years. A company I used to work for sold these for $1500. The reason people are willing to spend this money is because these are geared toward drag racing, mainly for weight reduction. Compared to other reduction paths, $1500 to remove 30lbs is cheap. The main thing to realize though is that this is a market geared towards people who have purpose-built a car to drive for 10 seconds at a time, a couple times a weekend. Everything geared toward this market is expensive, because basic entry into the market requires a relatively large investment, and companies know that consumers are willing to spend. Its a lot like the wedding industry, in that regard. On the other hand, high margins are the only way to make money in this segment, as the entire market is less than 100,000 consumers.

> Oh, and its lifespan (7 years) is about twice that of a lead-acid battery (3-4 years).

Nonsense; lead acid batteries easily last 5 years or more.

Since the article lowballs the life of a lead-acid battery, it's reasonable to suspect that it's likewise overestimating the seven year life of this new battery, which would make them about equal.

> They’re filled with garbage materials that are terrible for the planet.

More FUD. The garbage materials are sealed, and batteries get recycled. Places that sell you the new one take back the old one, generally.

Battery places are not going to know what to do with this new-fangled thing.

So it's down to the 6 pounds and gas mileage. Okay, realistically, let's talk about the environment now: this is for an internal-combustion-engine car that spews several tonnes of carbon into the atmosphere. If you want to save the planet, ride a bicycle. Still, this could make in excess of a one percent difference in fuel economy, which is significant, and will easily more than pay for the battery. Say you spend 200 bucks on fuel per month. Get 3 of those back thanks to the 6 pound battery, that's 36 over 12 months. If it holds up for 10 years, 360 saved.

Easier on the lower back is a plus. For many people, this is a do not care; only the DIY battery swappers who do it in the parking lot will be somewhat relieved, as well as the people who swap batteries as part of their work duties.

Poor capacity is a minus. People don't just run the stereo while parked; sometimes they have the headlights on or use other accessories, not always ones built-into the car. On a warm day you might listen to the stereo, and have a fan circulating the air. How about emergencies? If you're stranded somewhere with a dead engine, it's better to have more battery capacity than less for whatever. Flashing your lights at another car, say.

> They die without warning

That is not entirely true: there are in fact warning signs which, combined with age (being say > 5 years) add up to "change the battery". A lead-acid batter that has given you five warnings will then die without an additional warning, if five warnings is all which that battery has been blessed with. Those who don't recognize the warnings of course curse the battery for dying without a warning.

Who is to say this battery won't exhibit sudden failure modes? Suppose the business takes off and millions of these that are actually sold to consumers are made in sweatshops overseas, with all kinds of corners cut to save costs. Will those units still hold up? Let's compare prototype to prototype, shipping product on the shelves with shipping product on the shelves.

But a car alternator's output is nominally 13.8V.

if it is so smaller inside the big case, why not pack twice the caps and have double the running time/service life?

Battery relocation to the trunk is a standard mod for the gen3 rx-7, assuming you're speaking of that one.