[Mastro Gippo] recently purchased a wall mounted charger for his electric car that looked great and had all the bells and whistles he wanted. There was only one problem: the thing burned up on him. Looking to find out how this seemingly high-end piece of hardware gave up the ghost so easily, he took it apart and tried to figure out where things went wrong. While he’s not looking to sling any mud and actually name the company who produced the charger, he certainly has some choice words for whoever green-lit this particular design.
With the charger open, there’s little doubt that something became very toasty inside. A large swath of the PCB has a black char mark on it, and in some places it looks like the board burned right through. After a close examination, [Mastro] is of the opinion that the board heated up to the point that the solder actually liquified on some connections. This conductive flow then shorted out components below it, and things went from bad to worse.
But where did all the heat come from? [Mastro] was stunned to see that a number of the components inside the charger were only rated for 30 amps, despite the label for the product clearly stating it’s good for up to 32A. With components pushed past their limits, something had to give. He wonders how such a device could have made it through the certification process; an excellent question we’d love to know the answer to.
The worst part is, it looks like the designers might have even known there was an overheating issue. [Mastro] notes that there are heatsinks bolted not to a component as you might assume, but directly to the PCB itself. We’ve seen what happens when designers take a cavalier attitude towards overheating components, and the fact that something like an electric vehicle charger was designed so poorly is quite concerning.
The popular press was recently abuzz with sad news from the planet Mars: Opportunity, the little rover that could, could do no more. It took an astonishing 15 years for it to give up the ghost, and it took a planet-wide dust storm that blotted out the sun and plunged the rover into apocalyptically dark and cold conditions to finally kill the machine. It lived 37 times longer than its 90-sol design life, producing mountains of data that will take another 15 years or more to fully digest.
Entire careers were unexpectedly built around Opportunity – officially but bloodlessly dubbed “Mars Exploration Rover-B”, or MER-B – as it stubbornly extended its mission and overcame obstacles both figurative and literal. But “Oppy” is far from the only long-duration success that NASA can boast about. Now that Opportunity has sent its last data, it seems only fitting to celebrate the achievement with a look at exactly how machines and missions can survive and thrive so long in the harshest possible conditions.
Continue reading “Engineering For The Long Haul, The NASA Way”
There’s a reason we often use the phrase “It ain’t Rocket Science”. Because real rocket science IS difficult. It is dangerous and complicated, and a lot of things can and do go wrong, often with disastrous consequences. It is imperative that the lessons learned from past failures must be documented and disseminated to prevent future mishaps. This is much easier said than done. There’s a large number of agencies and laboratories working on multiple projects over long periods of time. Which is why NASA has set up NASA Lessons Learned — a central, online database of issues documented by contributors from within NASA as well as other organizations.
The system is managed by a steering committee consisting of members from all NASA centers. Public access is limited to a summary of the original driving event, lessons learned and recommendations. But even this information can be quite useful for common folks. For example, this lesson on Guidance for NASA Selection & Application of DC-DC Converters contains several bits of useful wisdom. Or this one about IC’s being damaged due to capacitor residual discharge during assembly. If you ever need to add a conformal coating to your hardware, check how Glass Cased Components Fractured as a Result of Shrinkage in Coating/Bonding Materials Applied in Excessive Amounts. Finally, something we have all experienced when working with polarized components — Reverse Polarity Concerns With Tantalum Capacitors. Here is a more specific Technical Note on polarized capacitors (pdf): Preventing Incorrect Installation of Polarized Capacitors.
Unfortunately, all of this body of past knowledge is sometimes still not enough to prevent problems. Case in point is a recently discovered issue on the ISS — a completely avoidable power supply mistake. Science payloads attach to the ISS via holders called the ExPRESS logistics carriers. These provide mechanical anchoring, electrical power and data links. Inside the carriers, the power supply meant to supply 28V to the payloads was found to have a few capacitors mounted the other way around. This has forced the payloads to use the 120V supply instead, requiring them to have an additional 120V to 28V converter retrofit. This means modifying the existing hardware and factoring in additional weight, volume, heat, cost and other issues when adding the extra converter. If you’d like to dig into the details, check out this article about NASA’s power supply fail.
Thanks to [Jarek] for tipping us about this.
One dark and stormy morning, Dr. Richard Noirimetla, private failure investigator, was sitting at his desk nursing his morning cup of joe. It was an addiction, but life, and engineering was hard. Intense eyes sat in a round dark-skinned face. An engineering degree from the prestigious Indian Institute of Technology hung from the wall in his sparse office. Lightning flashed outside of his window, as the rain began to beat even harder against his corner office windows.
His phone rang.
“Hello, Dr. Noirimetla, Private Failure Investigator here.” He said in deep, polite voice. “How may I help you?”
“Ah, I’m Chief of Manufacturing for Galileo Concrete Pillars Inc. We have a bit of a problem here. We used to see a failure rate above 33% for our concrete pillar operation. As part of our lean manufacturing efforts we tried to reduce that number through various improvements. However, we see a failure rate of almost 50% now. We expect foul play… from one of our suppliers. Can you come right away?” a worried man’s voice sounded over the phone.
“I see, that’s very troubling,” Noirimetla rumbled. “I’ll send over the contract detail. There will be an increased fee, but I’m on my way.”
“Sounds good, we’ll pay anything! Just get our operation up to standards!” The man bid a polite goodbye and hung up.
Continue reading “Dr Noirimetla, Private Failure Investigator And The Mystery Of Galileo’s Pillars”