[Raion]

Nuclear batteries in cars... Great idea. Have a small highly radioactive piece in a vehicle that has no guarantees of being on über smooth paved roads.

But sure, batteries will improve, but there's only a specific physical limit and for lithium (one of the lightest metals) we have fast approached it. It may be practical in a tiny European nation like the UK or the Nederlands, but the US? People underestimate the size. France is barely the size of Texas. To drive from the northeastern border with MD to say, Wise, VA alone is an 8 hour drive realistically with traffic and fuel stops. With battery stops? Probably closer to 9-10, if you can find chargers outside of the major metropolitan areas. The US is huge; you can go 400 miles without reaching a major metropolitan area, or more. It's not quite as bad as Australia where you have a vast interior with few/no fuel stations, but it can be brutal.

My biggest issue, back to the focus, is repairability. I can fix my truck or Subaru currently quite easily. I cannot fix even a Nissan leaf without potentially killing myself from AC power.

[robespierre]

I think in the next ten, twenty years we will see massive improvements in battery technology. Even in the last few years we've seen gigantic improvements. Last week I was reading about nuclear diamond battery tech.

Any electrical engineer can tell you that "nuclear diamond battery tech" is a scam. The potential power output of betavoltaic devices is a few milliwatts at most, and the companies promising that "in the future" they will power cars are 100% scam artists with no legitimate activity whatsoever. The truth is that betavoltaics have very limited applications for things like radiosondes, but you can't scam millions of gullible idiots by saying "radiosondes!". Anything involving thermoelectric generators is also likely a scam.

You need to get your technology information from more reliable places. Battery technology has not seen "gigantic improvements"—it has evolved very slowly since the commercialization of the nickel-cobalt lithium ion cell in the 1990s.

[vishnu]

Funny battery story, in 2007 the Naval Undersea Warfare Center came to us asking for a power supply that could mimic the output of a rotating machine that they wanted to use on their submarines to power coil gun launchers to replace the compressed air used to launch torpedoes, with the idea obviously being that the coil gun launch would be vastly quieter than the compressed air. We wanted to use capacitors but the Navy insisted we use batteries. So the eventual design was implemented using 350 Optima Redtop absorbent glass mat batteries, configured as five parallel strings of 70 batteries each, which were switched into the load by integrated gate bipolar transistors. In the end the Navy never got funding to pursue the coil gun concept. Apparently, submarine torpedo warfare isn't a major concern for the world's navies anymore. 😄

[Irinikus]

Funny battery story, in 2007 the Naval Undersea Warfare Center came to us asking for a power supply that could mimic the output of a rotating machine that they wanted to use on their submarines to power coil gun launchers to replace the compressed air used to launch torpedoes, with the idea obviously being that the coil gun launch would be vastly quieter than the compressed air. We wanted to use capacitors but the Navy insisted we use batteries. So the eventual design was implemented using 350 Optima Redtop absorbent glass mat batteries, configured as five parallel strings of 70 batteries each, which were switched into the load by integrated gate bipolar transistors. In the end the Navy never got funding to pursue the coil gun concept. Apparently, submarine torpedo warfare isn't a major concern for the world's navies anymore. 😄

The switching circuitry on your rail gun power supply must be quite something!

[vishnu]

The switching circuitry on your rail gun power supply must be quite something!

It is, they're just big-ass thyrsitor stacks in very a carefully designed clamp configuration. The biggest problem with solid-state switching at that energy level is that even if your semiconductor presents a pretty big surface area to the storage, when you make the switch if the entire surface area of the semiconductor doesn't become conductive right away, for example say just only the center portion of the semiconductor becomes conductive, the entire storage will dump through that area before the rest of the semiconductor can activate, and the switch is toast. You have to throw it away and buy a new one. And, needless to say, they're EXPENSIVE! That's why flatness and the clamping load are critical to avoid having to write big checks to the semiconductor manufacturer after every shot... 🤪

[Irinikus]

The switching circuitry on your rail gun power supply must be quite something!

It is, they're just big-ass thyrsitor stacks in very a carefully designed clamp configuration. The biggest problem with solid-state switching at that energy level is that even if your semiconductor presents a pretty big surface area to the storage, when you make the switch if the entire surface area of the semiconductor doesn't become conductive right away, for example say just only the center portion of the semiconductor becomes conductive, the entire storage will dump through that area before the rest of the semiconductor can activate, and the switch is toast. You have to throw it away and buy a new one. And, needless to say, they're EXPENSIVE! That's why flatness and the clamping load are critical to avoid having to write big checks to the semiconductor manufacturer after every shot... 🤪

I spot one of your thyristor stacks!



That's one awesome piece of machinery!

[vishnu]

I spot one of your thyristor stacks!

That's one awesome piece of machinery!

Can you believe the Navy actually thinks they can put that monstrosity on a ship? I've always said railguns will finally work when the material scientists come up with the required  unobtainium. Yes, I know, the old jokes are the best... 😄

[Irinikus]

I spot one of your thyristor stacks!

That's one awesome piece of machinery!

Can you believe the Navy actually thinks they can put that monstrosity on a ship? I've always said railguns will finally work when the material scientists come up with the required  unobtainium. Yes, I know, the old jokes are the best... 😄

That would certainly pack a punch, with a large sabot-type projectile travelling in excess of 2300m/s!!! (I certainly wouldn't want to be on the receiving end of that!!!)

[vishnu]

That would certainly pack a punch, with a large sabot-type projectile travelling in excess of 2300m/s!!! (I certainly wouldn't want to be on the receiving end of that!!!)

Thing about it is, APFSDS (armor penetrating fin stabilized discarding sabot) rounds are only used in direct fire systems, they're pretty much worthless for naval artillery. Unless the target is within a few kilometers. And, if the target is that close it's probably a Somali pirate skiff, so they wouldn't engage with their main armament. They shoot at those guys with their 50s.

[Irinikus]

That would certainly pack a punch, with a large sabot-type projectile travelling in excess of 2300m/s!!! (I certainly wouldn't want to be on the receiving end of that!!!)

Thing about it is, APFSDS (armor penetrating fin stabilized discarding sabot) rounds are only used in direct fire systems, they're pretty much worthless for naval artillery. Unless the target is within a few kilometers. And, if the target is that close it's probably a Somali pirate skiff, so they wouldn't engage with their main armament. They shoot at those guys with their 50s.

I see your point!