[Tilt, TyTN II, MDA Vario III General] DrXDA:
Confirmed - Serious GPS battery drain problem!

[Originally posted in an

older thread

by mistake, I'm re-posting it here - Sorry for double-posting!]

Hi BusterTyTN and many thanks for this thread!

I'm experiencing the exact same problem as you (and I believe many other Kaiser users out there). The strange thing is that it started happening only a few days ago (I have my Kaiser for nearly 3 months). Well, at least that's when I discovered it. Initially I thought it had to do with 3rd party applications, etc., so I reverted to some old backups, but the problem still persisted. I then did a hard-reset (fresh original HTC ROM with .32 radio) and only installed Destinator 7, nothing else. Guess what? The problem still appeared. Before running Destinator 7 the battery drain on standby was almost zero (around 1-2% per day). After running Destinator 7, GPS locked, then exiting, no other applications running, I got around 6-8% drain per hour (on standby)!

I'm an electronic engineer myself (doing embedded designs with PIC microcontrollers) and understand your post about the current drains in different modes, etc. I also have a digital scope & multimeter in my lab and was actually thinking of doing the measurements myself until I came across your thread!

I wonder if there's someone out there who can write a small utility to shut down the GPS unit manually after exiting a GPS s/w. This could be used in a script to be executed automatically upon exiting such s/w. Not a great solution, but better than a soft-reset.

Also, based on the post by CdB in

this thread

, I wonder if this is an enumeration issue. I mean, maybe the GPS driver keeps track of how many applications have turned on the GPS unit, and this counter needs to go down to zero for the driver to shut down the GPS unit. So, if a badly-written s/w opens the GPS unit (and counter incremented) and then doesn't do a proper request for closing the unit (so the counter does not return to zero), the driver will be fooled into thinking that the GPS is still needed and thus will not shut it down. This reminds me of the stupid Windows 95/98 DLL registration engine where it counted how many applications used a DLL so it could remove it from the system during uninstallations when the counter reached zero. I find this technique really stupid and prone to errors (it only takes one miscount to mess things up).

The weird thing in all of this is that the orange LED on the Kaiser stops flashing when I exit Destinator 7, meaning that the GPS unit is shut down. Apparently, this is not a reliable indicator of GPS activity... Also, another strange thing is that, during my experiments yesterday, I've managed to make it work properly once (properly powering down after GPS use). I guess this was only a random thing... :(

[Edit: Reading more on this thread explains the randomness of occurrences... It seems that the problem is intermittent. In my Kaiser it seems to happen 9 out of 10 times or worse, which is pretty bad! Note that this happens only when the Kaiser is in Flight Mode (nothing on). I've had the Kaiser for almost 3 months and I only discovered the problem a few days ago. Why? Because I normally never shut down the phone module, but during the last few days I had it switched to Flight Mode and only used the GPS, which triggered the problem. My observations totally confirm BusterTyTN's results mentioned in the first post of this thread. This is a real problem and doesn't seem to be affected by 3rd party applications. It appears to be either a h/w issue of the QUALCOMM chip, or a badly-written GPS driver issue. HTC, are you listening?]

Many thanks again for the great thread!

DrXDA