Peter, I´ve had my iPad Mini 4 run for more than four hours using Foreflight or SkyDemon, I usually turn brightness down a little though. I have recently done an eight hour flight in a glider running SkyDemon with the screen turned off mostly. The iPad still showed more than 50% after landing.
When I tested Jeppesen MFD VFR two years ago it turned out to use about twice as much battery power, the iPad was almost empty after a two hour flight.
I carry a powerbank on longer trips but try to avoid charging when in flight.
The interesting thing would be GPS reception in the TB20, which never worked reliably with the old Ipad. I have a proper rooftop antenna feeding an NMEA bluetooth receiver but failed to find an IOS-compatible bluetooth GPS receiver has an external antenna connection, since Steve Jobs decided NMEA was too standard and refused to use it. Lots of previous threads – example example.
Not only thermal issues but GPS reception issues.
I get 4-5 Hrs with iPad2, 4 hrs with iPad 3rd gen, and about 4Hrs with iPad mini. I do carry a battery pack and used it on a 8Hr flying day recently.
The biggest hazard as I mentioned before is forgetting to charge the devices in the hotel the night before!
Peter wrote:
Not only thermal issues but GPS reception issues
I’ve never had any issues (to date!) with internal GPS reception on any iPad over at least 1000 Hrs, save one occasion in Norway when the 430 went out as well.
Plenty of Bluetooth GPS receivers which are Apple compatible – the Garmin Glo, Dual and Bad Elf spring to mind – I have used all three and all work well but I have a preference for the DUAL over the Glo as it stores track logs as well.
If you want an iPad mini the rumour is that they will be stopping production.
I have a Pro 10 inch and really happy with it
1) on a Bright day, the screen was miles ahead of a mini
2) The pencil (now available on cheaper ipads too) is great to note clearances / atis etc.
I had it overheat, not in the plane (Diamonds and Cirrus), but when at the beach (using it as a Kindle) at lower latitudes when the sun is hitting the screen at a more perpendicular angle (the dark case I use to protect from drops certainly doesn’t help with cooling either)
Plenty of Bluetooth GPS receivers which are Apple compatible
Indeed, but as per those linked threads, none seem to have an external antenna option, whereas with NMEA GPSs you have various products which can give you a bluetooth GPS with a proper rooftop antenna. That was the reason I originally binned the Ipad for flying. The inability to connect to a Thuraya phone and some other stuff came as later factors, but the ADL150 avoids the Thuraya issue (and with a much better reliability albeit at a substantially higher cost, and no “internet”).
It would be interesting to borrow a current Ipad Mini 4 and see how well it works in the TB20, but IIRC the GPS API Apple provide doesn’t enable seeing the signal levels from the satellites. Has this changed i.e. can you run an app which shows the constellation and the various signal levels?
Happy to lend you an iPad2 anytime Peter!
Interesting thing about the 3rd gen iPad is that it works with FF in Flight Mode inside the 747! Earlier iPads would not work without 3G enabled, and even then (which obviously I’ve not tested) still would not get signal inside the aircraft.
I’ve been using a DUAL for years now and never had an issue, it lives on the dash with a clear view of the sky. Cannot see why that wouldn’t work in a TB20. The DUAL App also shows you the satellites and signal strength. For me it’s now becoming largely redundant, as the planes I fly recently had ADS-B installed and the iPad gets the GPS signal (and wx and traffic) from the installed gear via Garmin Flightstream.
Thank you Aveling, but I have an Ipad2 
It is pretty unreliable with the GPS (in my TB20), shuts down readily when warm, and cannot support the IOS version which is required for e.g. Foreflight.
I bought the Dual GPS and while it worked with the Ipad, there were some issues with external power and turning it on/off. I posted about it somewhere here before. I went on Ebay… Indeed, they supply an app which showed the signal levels; I remember that now.
