How to reduce chances of a hoverboard fire

Wired has a good article on fires from “hoverboards,” which are essentially very small hands-free electric scooters. Here is an example. Start at about the :30 mark to see how these devices explode, and can easily set a house on fire.

Neither Wired nor other news stories have much constructive advice about how to reduce the chance of fires. As they point out, buying a well-made model is important, but at present there is no way to distinguish the well-made ones from the knock-offs. And most are cheap knock-offs by companies that will be gone in a year.

I have some experience with the underlying cause of these fires,  their Lithium-based batteries, because I use them in radio controlled aircraft. Fires of these batteries are not common, but they happen. Two people in San Diego who I know directly have had major fires. One lost a 2-unit condo, the other a detached workshop. The second one happened to an expert in RC flying!

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The amazing story of Apple’s chips

With the new A9 and A9X chips in its iPhones and iPads, Apple has mobile chips that are better than Intel’s. In fact Apple’s chip business is a very impressive technology story. I don’t have time to put together a full analysis, but I have collected some recent articles. figure-2

Many sources are suggesting that Apple’s current chip generation (A9 and A9X) is better than Intel’s in low-power (mobile) performance. I guess it’s not news that Intel is behind Qualcomm in mobile, but I still find it surprising that Apple’s own chips are apparently better than X86 for Macintosh low-end laptops!

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Autonomous vehicles – how skeptical should we be?

I have gone up and down on the prospects for  autonomous vehicles (AVs). There are a lot of technical hurdles, and probably as many social issues such as how liability laws will be written. The Google car has been over-hyped. But today I received a claim that AVs are not feasible until 5G wireless networks are ubiquitous.

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Amazon is blowing smoke about drone delivery

Amazon Delivers Some Pie in the Sky –

I’m not impressed by Google’s “aerial delivery.” It’s easy to demonstrate a show system. But it will be very hard to create a safe system that can deliver loads of a few pounds, at a distance of even a few miles, much less the 10 that Jeff Bezos apparently claimed. Or to deliver to a specific person in an apartment building.

Here’s a quick response I wrote on Andrew McAfee’s page about this.

I’m skeptical. There are real safety issues here, as well as weight/payload/power issues. To deliver a 2kg package 30 km will take a vehicle gross weight > 6 kg (rough numbers). And helicopters, unlike fixed wing,  are “fail-dangerous.” Not to mention problems of delivering to a specific person in an urban environment. So I call “pie-in-the-sky” on this.

I see others are being skeptical because of regulatory problems. Yet other countries are way ahead of U.S. on regulation, and I don’t think regulation is the fundamental problem. The real problems include safety and payload:

  • Helicopters (actually, multirotors) have very limited endurance and therefore range. You can put a big battery on them, but then you need a bigger machine to carry the weight.
  • They have limited payload. Four ounces is no problem; but 5 pounds requires, right now, a machine with a total span of about three feet.
  • At least six motors and props will be needed (called a hexacopter). Otherwise, failure of a single engine would cause an immediate crash. Even with six or more rotors, a total power failure, or a guidance  failure, causes a crash. In a crash, the operator has  zero control on where the machine ends up. This is unlike an aircraft.
  • A machine this size that crashes is big enough to kill someone underneath. Especially if some of the motors are still operating. Even professionals are very careful about what they fly over. You can see videos on Youtube of idiots flying over crowded beaches, but a few people have been badly hurt this way, and the number will grow.
  • Navigation using programmed routes is straightforward in clear areas, by using GPS-based-autopilots. But with obstacles (trees, buildings) a lot of development work remains. This problem, unlike the others, will be solved eventually by Moore’s Law.
  • If you use an aircraft (wings) instead of a copter, many of the safety issues get much better. But on the other hand, you need a much larger area to land in. You can’t land in someone’s back yard.

Most of these problems are due to laws of physics, not the capability of current electronics. In short, delivering packages is an active area of R&D, but it will be feasible only in  situations where it is almost useless:

  • When you will be flying in unpopulated areas
  • When you can afford to crash, and lose, a few percent of your vehicles.
  • When the load is small, and the range is short.

There may be  some cases that fit this description, but very few. For the next 5+ years, using drones for that don’t have to land remotely – mainly for remote sensing – is going to be the only practical application. Unless you have a military budget, of course.


Million-Year Data Storage Disk Unveiled

Million-Year Data Storage Disk Unveiled | MIT Technology Review.

This is impressive, although perhaps not too practical. They are using lines scribed on tungsten. The underlying data is expressed as QR codes (which will be forgotten in a few centuries at most, but that is a different problem.)

SEM look at storage disk

One problem is that they are using 100nm line width. While impressive, at that width it is invisible to optical devices (which have a limit of approximately 1 micron) without very complex optics and electronics. So they are going for high density, rather than long-term readability. On the other hand, it would be great for a 50 to 100 -year storage, which is longer than any existing technology can reliably handle.

Software, Design Defects Cripple Health-Care Website –

Software, Design Defects Cripple Health-Care Website –

Poor software design is still common. I notice the developer was Experian, a private company. Outsourcing the web system for the Affordable Care Act was the right idea, but looks like they picked a weak company.

It will be interesting to get a post-mortem in a year or two. I hope someone writes it up for the New Yorker. It should make a good case study on software product development.

System is down...

System is down…

What happens if California’s solar panels start to fail over the next few years?

Solar Industry Anxious Over Defective Panels – had not solar panel quality was becoming such an acute issue “so soon.” Judging by this NYT article, many Chinese-branded PV panels are not reliable.  This article sounds straight out of the book that Barry Naughton pointed me to, Poorly Made in China. The performance degradation  data on well-made panels is pretty encouraging: 0.5% per year is typical, but the key is well made. There are many manufacturing shortcuts and quality problems that will lead to failure of electrical connections after a few thousand temperature cycles, for example. (Think night/day in Colorado!)

testing solar panels

Power inverters, which are straight power semiconductor products, apparently may also be unreliable.

It will be interesting to see what this problem with Chinese panels leads to in trade/market share. California and other states that subsidize PV should only pay for systems that pass good certification – for both performance and safety. For obvious reasons, testing long-lifetime behavior of electronics is very tricky.I wonder if we will   see a repeat of the “solar water heating” fiasco of the 1980s, when lots of houses put pool heaters on their roof that started to leak and ended up getting ripped out. When the economics of a project are based on a 20 year life, and it only lasts 5 years, that is a colossal fail. If it catches on fire, as described in the NYT article, that is another situation entirely!  What is the typical guarantee for homeowners in California?