I recently had my 3GS running and had the GPS and compass running in my car and had the car charger plugged into the iPhone also. After about 30 minutes, I noticed that the charge was still going down. It appears that when the GPS and compass are running, the power drain is so great that you will eventually still run your battery down.

Has anyone else seen this issue?

I haven't noticed that but I only ran it like that for 1 trip so far that was 30 minutes... I didn't think to check battery levels.. I did notice it was quite warm though.

Humm thats interesting

David maybe you can test this ? ?

If you have some spare time to read, follow this link. Maybe something there will address your concerns.

Well... I guess it must not be a rampant problem about the not charging since the second link in your link is this post and there are no others...LOL.

As far as battery drainage for some people who are getting alarmed.. I'll bet it's people with new phones. I have had 2 now and noticed that the battery seems to drain fast.. at first. Then the life gets better... maybe because it takes a while to calibrate itself.

I'm using a jailbroken 3G iphone, and I've got (amongst a lot of other cool stuff) a percentage count next to my battery charge bar. What this has led me to discover is that there's a lot of difference between how much charge the battery carries when the display reaches 100%, and what it carries if it's left charging for a couple of hours after that.

If you only charge the phone up until the indicator has just reached full, you're not charging the battery fully, and it runs down a lot faster. If I leave the phone charging overnight, it takes most of next the day of use before it even starts showing less than 100%, and more than a day to go below 90%. If I only charge it just until the system calls it 100%, it runs down to around 85% within a few hours of being unplugged, and after a whole day is down to around 60%.

Maybe everyone knows this already - but it's news to me that the system battery charge algorithm isn't very accurate.

Oh, and the process of charging the phone warms it up, even without using it heavily at the same time - but I've noticed that google chatting (for example) with the phone plugged in results in a phone almost to hot to hold comfortably.

Interesting.. I will leave it on the charger well after it reaches 100%. Thanks.