The issue in question, first reported late last week by video diagnostic and testing firm DisplayMate, is that the new iPad continues to draw a full 10 watts of power for over two hours following an indication by the on-screen battery meter the the device’s battery is at “100 percent.”
“At 2:00 hours after reporting 100% charge, the new iPad hardware started to reduce the charging power. At 2:10 the recharging cycle fully terminated with a sharp decrease in power. The new iPad battery is truly fully recharged 2 hours and 10 minutes after prematurely reporting on screen that it was fully charged,” DisplayMate’s Dr. Raymond Soneira told PCMag.com.
While it has been determined that the significantly larger battery in the 2012 iPad will take noticeably longer to charge than that of its predecessor, a necessity considering the increased power requirements of the most recent device, the battery capacity reporting issue concerned consumers and media alike. It appeared that, due to the supposed error in the capacity calculation, the iPad’s battery was truly only at 90 percent despite reporting 100 percent capacity.
In an attempt to address the concern, Apple VP of Product Marketing Michael Tchao spoke with AllThingsD Tuesday, stating that the confusion over the iPad’s battery charging stems from the way that all iOS devices handle the last portion of the charging process in an effort to preserve the longevity of the battery.
Michael Tchao, Apple VP of Product Marketing
According to Mr. Tchao, the latest iPads, along with all previous iOS devices, report the device as “100 percent” charged just before the battery actually reaches maximum capacity. From there, iOS will intelligently charge the battery to a “true” 100 percent, then discharge a point or two before recharging to 100. This process repeats until the user unplugs the device, ensuring that the battery remains fresh no matter how long the device is plugged in.
“That circuitry is designed so you can keep your device plugged in as long as you would like,” Mr. Tchao said. “It’s a great feature that’s always been in iOS.”
The decision by Apple to not display these small increases and decreases of capacity via the battery meter was made with the goal of not distracting or confusing consumers who, without knowledge of the way iOS handles battery charging, might believe that their device was malfunctioning. But regardless of what stage the charging process is at when the user unplugs the device, if the battery meter reads “100 percent,” the iPad will still operate for at least the advertised 10 hours, Mr. Tchao said.
Dr. Soneira, while pleased to see a response from Apple regarding matters of this character, was still not entirely convinced by Mr. Tchao’s explanation.
“If the iPad has cell and Wi-Fi and background tasks running, then I agree with Apple that it will cycle down and up,” Dr. Soneira said. “[But] my lab tests were in Airplane Mode so that did not happen and I measured the true battery state…My essential point is simply that if the new iPad is fully charged overnight, then my tests show it will run 11.6 hours, which is 1.2 hours longer than if it just charged to 100% [on the meter], or 10.4 hours. This will matter to some users.”
Speaking with AllThingsD on the matter, Yankee Group analyst Carl Howe summarized the situation by pointing out that battery charging processes are as much art as they are science.
“What’s really subtle is that consumers think they understand that 100% means ‘full’,” Mr. Howe said. “That might have been the case with older batteries, but today’s batteries have microprocessors managing their charging. So 100% is whatever that microprocessor says it is — it’s not any absolute measurement of ion concentration or anything…If it says it’s charged, consumers should assume it is, and not worry about whether the charger is drawing current.”
Battery image courtesy of Shutterstock, labels by TMO.