Tuesday, March 20, 2012

iPad 3 - Heat and Battery Issues

Just a quick update on two hot topics regarding the iPad 3 (aka the new iPad); heat and battery life.

Hotter not necessarily Better

Engadget has passed on some work done by Tweakers.net. Using an infrared camera, they photographed the iPad 2 and iPad 3 side-by-side. After five minutes of running the GLBenchmark app, the iPad 3 was about 5˚C warmer at 33.6˚C (92.5˚F) than the iPad 2.

Heat is certainly an issue for pilots using an iPad EFB in non-airconditioned cockpits in hot weather, but it's too cool in my neighborhood to provide any empirical data on the iPad 3 just yet. I can say that I've flown with both the iPad 1 and the iPad 2 in some hot weather and I saw my iPad 1 display the "Help me Spock, I'm too hot!" message, but only once. The outside air temperate at the time was over 100˚F. I simply turned the iPad 1 off, moved it to the shade, directed an air vent toward it, and it a minute it was operating again.

I've flown in similar temperatures with the iPad 2 and have never had it overheat, perhaps because I was more conscious of the possibility. The iPad has no internal fan and all the heat is radiated by the outside case, so the techniques I recommend for keeping any iPad from overheating are:

  • Don't run the display continuously
  • If possible, run the display slightly dimmed
  • Turn off 3G or 4G
  • Avoid cases and kneeboards that completely enclose the iPad
  • Avoid dark colored cases and covers
  • Keep the iPad out of direct sunlight
  • Direct an air vent toward the iPad
  • Don't leave your iPad inside a parked car or aircraft

If your iPad does overheat, turn it off and wait.

Battery Life

The iPad 1 and iPad 2 have demonstrated a solid battery life of at least 8 hours under intermittent use, but the iPad 3 with 4G appears to be a different story. It takes more juice to drive that high-density display and the latest 4G hardware. I flew with a pilot last night who purchased an iPad 3 with 4G and we tried an experiment. He started the flight with 97% battery capacity and he left cellular data and LTE turned on. I had 99% capacity on my iPad 3 WiFi.

After 35 minutes, his battery was down to 85% capacity while mine showed about 97%. He turned cellular data and LTE off which leaves the internal GPS on and functioning. After flying for another 45 minutes, his battery showed 78% capacity while mine showed 94%.

I should note that we were approaching dusk, we had both dimmed our displays about halfway through the flight. Another difference was that the 4G iPad's display was running pretty much continuously. My various app display options were set to sleep, so my iPad 3's display was probably on less that 50% of the time.

My recommendation for getting the most out of the iPad's battery (regardless of model):

  • Don't run the display continuously
  • When possible, dim the display
  • Use an external power adapter (charging will undoubtedly generate heat)
  • Use an external battery
  • Turn off LTE and Cellular Data while in flight
In ForeFlight Settings, turn on the option Allow Device to Sleep.

For Jepp MobileFD, go to iPad Settings, select JeppFD, and turn Sleep Mode on.

For SkyChartsPro, go to iPad Settings, select SkyChartsPro, and turn off Display always on.

If you are traveling and plan to use 4G while on the ground, you'd be well advised to carry an AC power adapter and use it.

Cost of Change

These two iPad 3 issues are not necessarily deal-breakers for those wanting to upgrade, but they will need to be managed. What, you thought you'd get razor-sharp graphics and fast wireless data for nothin'?


JohnOCFII said...

"What, you thought you'd get razor-sharp graphics and fast wireless data for nothin'?"


Well, not for nothing. The unit is a touch thicker and heavier, supposedly because of much greater battery density. Also, Apple made a big deal in the Keynote and on their data sheets about battery life not being greatly impacted.

I run with cellular data turned off. Maybe next time I'll try to turn the screen brightness down more, but I am certainly seeing (as you saw) much greater drain on the batteries than Apple would imply I would see:

From the Apple site: http://www.apple.com/ipad/features/

"The new iPad features a Retina display with four times the pixels of iPad 2 and quad-core graphics. How much of an effect does that have on battery life? Almost none. You still get up to 10 hours of power to read, watch, play, write, and create whatever you want, all you want."

And yes, I can and will deal with it. We have a car/plane charger, and I have an external battery pack, but still. I am underwhelmed.

John Ewing said...


Our popular and business cultures are rife with false promises, inflated claims, and wishful thinking. "You don't sell the steak, you sell the sizzle" may apply in more ways than one. Remember when the first Pentium processors were introduced? Remember the countless jokes and jabs about the "Intel space heater?"

One can get up to 10 hours of battery life with the iPad 3, but you have to make some sacrifices. It's understandable that people would want the same performance in terms of heat generation and battery life in the iPad 3 as they got with in the iPad 2. Given the current state of mobile computer/graphic chip/wireless data technology, it would appear this is a work in progress.

Folks who are really unsatisfied can probably make their case to Apple and get their money back. I have no plans to do this myself, but then I didn't purchase a 4G model. For my purposes, the iPad 3 wifi seems to be a better version of the iPad 2 wifi.

I wouldn't be the first to suggest that we view anything a given manufacturer says about their products with informed skepticism. It's the "informed" part that I'm trying to help address in my blog.

Jan said...

You recommend turning off cellular data while in flight. Aren't you legally obligated to do this anyway?

David Cheung said...


No, not unless you are operating under IFR, and even then there's some leeway. See 91.21(a)(2) and (c).

John Ewing said...

Actually, the relevant regulation would appear to be 47 CFR 22.925:

Cellular telephones installed in or carried aboard airplanes, balloons or any other type of aircraft must not be operated while such aircraft are airborne (not touching the ground). When any aircraft leaves the ground, all cellular telephones on board that aircraft must be turned off. The following notice must be posted on or near each cellular telephone installed in any aircraft:

“The use of cellular telephones while this aircraft is airborne is prohibited by FCC rules, and the violation of this rule could result in suspension of service and/or a fine. The use of cellular telephones while this aircraft is on the ground is subject to FAA regulations.”

The confusion artistes around whether or not this applies to cellular data. It would seem to me that it does.

Jan said...

Yes, because when cellular data is on, the cell phone is continually transmitting to and receiving data from cell towers (or at least trying to).

John Ewing said...


Many pilots are unaware of the specific regulation on cell phone usage in aircraft because it's not contained in Title 14, the part of the Code of Federal regulations with which pilots are more familiar. Title 47 is entitled "Telecommunications" and there is no reference to 47 CFR 22.925 in 14 CFR part 91.

For their part, the FAA has specifically agreed in AC 91-21.1B:

"The FAA supports this airborne restriction (on cell phone usage) for other reasons of potential interference to aircraft systems and equipment."

Some pilots are ... um ... original thinkers, folks who bristle at and ignore any rule they don't like. Some say this rule is antiquated, that there is no evidence that cell phones interfere with aircraft systems. Still, it's a valid rule until the FCC and the FAA decide upon something different.

EddyMac said...

Regarding cell phones being turned off during a flight, I believe the FCC (not FAA) rule came about because the towers could not handoffs with the cell phone travelling 400 knots ... would cause a bit of havoc on the FCC part of the system more so than the FAA part of the system. The reality of a cell phone being on during flight is that you will occasionally hear your cell transmitting over your intercom and radios if it is too close. I would think for a commercial flight they would strategically place the antenna and have filters so that this is not an issue for people who may forget to turn their phone off.

John Ewing said...


Your suppositions sound good, but they are simply suppositions.

The FCC reg doesn't restrict cell phone use on aircraft traveling at a high rate of speed, it specifies "any airborne aircraft" and that would include even a hot-air ballon drifting along at 5 knots.

The FCC reg is pretty clear. It may need to be updated to account for new technology, but as of yet it hasn't been updated and is the "law of the land." I wouldn't be the first to point out that Americans have a love-hate relationship with law and order.

I'm not intimately familiar with the technology that some airlines are using (going to use) to allow cell phone usage in the air. One would assume they will have a mini cell on board that the phones will lock onto. I have read that the usage is limited to 6 phones at a time. I don't know how that mini-cell communicates with ground-based transmitters, perhaps it is via satellite.

This is pretty far removed from the issue of iPad cellular data transmissions tying up ground based cell towers. Given how easy it is to jam GPS signals, I'd be hard-pressed to allow someone onboard my aircraft to have a device not in "airplane mode" while flying in the clouds.