Iphone charging USB vs Outlet on heat generated?

[divang]

I just noticed that charging from the usb to the outlet that the outlet causes the iphone to heat up way more then the usb does.

The usb stays a pretty constant lukewarm feel while the outlet the first maybe 20 minutes was 3 times warmer but then towards the end of the charging cycle it cooled down to about the level of a usb.

It this just because the usb charges at a slower pace then compared to the outlet charing it faster cause it to heat up more then the usb? Anyone experience this?

Most of the past phones I've owned never heated up, not unless you used it while it was charging which i haven't with this phone.

 

[philgilder]

edit: read post below.

 

[hotshotharry]

My plug in adapter rates power output at 5v 1A. Typically usb ports are spec'd at 5v 500ma (.5A)

Therefore it is quite possible that the iphone charges faster at the beginning than the end, which would be consistent with constant voltage charging.

Perhaps a timed charged test would clear up the difference. Or if someone had an amp meter they could simply measure it. I dont have access to those tools at the moment ...

 

[divang]

ESP anyone elses experiences with this or thoughts? I just charged the phone earlier at half power with a outlet and the phone stayed cool the entire time. Seemed to only heat yesterday when I charged it at a extremely low battery level. Maybe that's a cause to?

 

[dizzy13]

I tested this to post on my blog and this is what I came up with

They seemed to be pretty close up until about 80% and then it took almost an hour longer to hit 100% than on the outlet

 

[rannddeee]

when i charge with usb at 10% baterry life, it takes about 30-40 minutes to get to 90%. it takes another 30-40 minutes to fully charde from 90% .