Over the last month, reports have surfaced that the HP Chromebook 11 (but not its larger sibling, the HP Chromebook 14), which went on sale in October, has had problems with its power adapter overheating. In November, HP and Google pulled the little Chromebook from store shelves, stated that the two companies would work with the Consumer Product Safety Commission on an investigation, and issued a warning to consumers who had already bought these Chromebooks not to use the included charger. The advice given to these consumers was to charge the HP Chromebook 11 with any other UL-listed micro-USB charger.
The companies did not issue a recall and none of the reports state that the overheating chargers are a safety hazard, and none of them are bursting into flames. Still, it seems odd to us that the best advice HP and Google can give to customers is to find a power adapter from a different product and use that instead of the one provided.
We have an HP Chromebook 11 in the Consumer Reports lab awaiting a coming test of the Chromebook category, and we've been wondering what to do about this device. Consumer Reports has made multiple inquiries to HP and Google, but we've heard nothing back. We also called the CPSC, and were told by a representative that the agency was looking into it, but that the organization could not comment on an ongoing investigation—so no new news there.
Out of curiosity, we measured the surface temperature of the HP Chromebook 11's charger with an infrared thermometer and got a reading of 140° F. That seemed pretty toasty, considering that other chargers from typical tablets and laptops we measured run at temperatures between 90° F and 105° F. But it doesn't answer the more fundamental question: How hot is too hot?
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To get some clarity on that, we spoke with John Drengenberg, consumer safety director at UL (Underwriters Laboratories). UL sets the standards for safety on many electronics devices. Drengenberg said that the company does have internal and external temperature standards for chargers.
When we asked for a specific surface temperature that such devices should not exceed, Drengenberg said that UL's external temperature limits vary based on the materials used for the power supply's enclosure.
"I can tell you from my years of working in the lab that I can barely keep my fingers on a product that is at 55 degrees Celsius [131° Fahrenheit]," he said. "My threshold of pain is right there. Now is that a fire hazard or a shock hazard? I don’t know."
Because the HP Chromebook 11 charger was UL-listed, Drengenberg said that he expected UL also will be conducting an investigation. As for the advice from HP and Google to simply use another charger, we tried that, with varying results.
Charging flexibility was supposed to be one of the original selling points of the Chromebook 11—because it uses the same charging standard as many other devices, you only need to bring along one charger when you're on the road. But the Chromebook 11's charger is rated for an unusually high 3.0 amps, and when we plugged in a lower-amperage microUSB charger from another device, we got a message on the Chromebook that said: "Low-power charger connected. Your Chromebook may not charge while it is turned on." So as far as we're concerned, that's definitely not a long-term solution.
Whatever the case, we hope HP, Google, the CPSC, and UL get this sorted out soon. Nobody seems to be offering refunds on the Chromebook 11, and if the chargers from other devices don't deliver enough juice to power the HP Chromebook for normal use, it seems like a severely hobbled machine.
—Glenn Derene
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