A little history first. When I first got my iPhone 3GS it changed with everything, my iMac and a variety of chargers including an iHome I got for a present. Around the time I uploaded a firmware patch to the iPhone, the one that corrected the signal strength meter for cell reception, I started getting warnings about being plugged into an unsupported charger. At first they were intermittent and I didn't pay them serious attention because unplugging & plugging the iPhone back in usually resolved the issue. Unfortunately it got progressively worse. I would get the message every time and I could only get the iPhone charged by leaving it plugged into the fairly new iHome almost all the time. I had tried everything including cleaning the contacts, blowing air on the contacts, resetting the iPhone, powering it on & off, everything. I finally decided to try one more thing. Since most of my chargers were at least a year old, with the exception of the iHome, I decided to buy a new charger. Not just any charger but one rated to charge the iPad. Well it worked. I got the unsupported charger message the first time I plugged it into the new charger but I just unplugged it and plugged it back in again & haven't seen it again as long as I'm plugged into the new charger and it's been 3 weeks. The curious thing is that the iPhone will now charge on the iHome OK & I only see the message intermittently now. The iPhone also seems to charge a lot faster now than it used to when plugged into the new charger.
By the way, if anyone is interested the charger I'm using is the Griffin PowerDuo 10 watt charger for iPod, iPhone & iPad. It comes with both a wall & car charger & cable.
