So, a logical question might be: "What kind of dummy wouldn't think about a rather strong magnet close to their compass? (any kind of compass)
ME, that's who! ...only in my case, it was the case for my Nexus 7 that had that strong magnet... ...it took me a long time to figure out why it displayed practically the same readings no matter which way I pointed it :-(
I did, though, eventually figure that part out on my own...
My bigger problem, though, is that I've installed GPS status on three of my devices (Nexus 7, Droid Incredible, and Droid Bionic), calibrated the heck out of all three; been through GPS status' excellent operator's manual and FAQ's...
...and nothing seems to work! Not one of the three devices give similar readings or headings; none of them are close to my two conventional compass(s).
Now, I'm wondering if the "kickstands" on my two phone cases (which are not magnets, but are metal) might also be causing interference?
I know about where south is, but I'm installing some solar panels (with a ground mount), and want to get them perfect.
Thanks for some of the excellent information and suggestions; I'll try those.
Of course, the best and most accurate way to find true south is to look up "solar noon" for your location, and find the exact time for any given day when the sun is exactly half-way through it's travel across the sky (exactly half-way between sunrise and sunset; it's a different time on any given day); drive a long stick in the ground... ...On the date you've chosen, at that exact time, drive another stick in the ground at the end of the shadow created by that first stick. That line will be exactly North/South (with no magnetic interference of any type).
Of course, that process is rather time-consuming and cumbersome, and can often consume two days of your time. It sure would be nice to possess the "perfect" compass, electronic or otherwise, that would reliably instantly point to true south or that "perfect" east-west line on which you want to mount your panels.
One would think that a high-quality, GPS-assisted smartphone and the right app would be ideal to provide that accuracy; it's somewhat depressing when you own three devices that fit that description and can't even get any two of them to produce the same readings.
To be fair, though, I can't be too hard on my Androids... ...I've got a $400 Casio watch that provides many of the same functions with GPS, compass, altitude, barometer, etc (Casio Titanium Solar Pathfinder PAW1100T) that I've had for 8 years, and it displays the same type of semi-reliable accuracy