I took APRSIS-CE for it's first portable outing today, with my HTC Touch phone running on batteries only. I found a few issues that made this outing a bit less successful than I'd hoped for.
For some reason on my phone the "turn off backlight if device is not used" power saving option doesn't seem to work. The screen only goes blank after xx minutes when the "Turn off device if not used for xx min" option is enabled. This option appears to have the same effect as pressing the button on the top. When the device is off, it is still connected to APRS-IS and can receive APRS messages but GPS tracking is off. The only way to keep tracking while portable is to disable the "Turn off device" option altogether and not to switch it off when putting it in your pocket. However having the backlight on while the phone is in a case in my pocket is a waste of current and doesn't help the battery endurance any.
On the plus side, the battery drain was a lot less due to the fact the GPS was only activated when I took the phone out of my pocket to check it. In fact after 3 1/2 hours it was still showing 75% capacity.
But for some unknown reason I would often find that APRSISCE had disappeared the next time I turned on the phone. One time it had tried to close after a message had been received and the only trace was a window called WM_CLOSE that said "You have unacknowleged messages." The program would not restart after this and I had to poke the phone with a stylus to reboot it. Another time there was a messaage about "Odometer failure." Other times it vanished without trace. The only times the program kept running were when I pressed the button on the top to switch off the phone before slipping it into its case and putting it in my pocket. Because it was in quite a stiff case I don't think anything could be pressed to close the application while the phone was in my pocket.