Can anyone explain why the battery overlheats?

[asuh]

I'm sure my understanding of what's going on with this phone is limited. I haven't read anywhere why the phone overheats while charging. It really makes no sense why this happens when the solution is so simple!

So, as I've experienced, my battery overheats. It overheats under the following conditions:

- talking on phone for more than two hours
- using wmwifirouter
- using Google Maps with GPS enabled
- using any software which uses the radio signal

Basically, using the phone for extended periods of time drains the battery extensively. Sometimes, the battery life isn't as good as it should be but, technically, there's a solution!

Plug it in!!

Plugging the phone into its charger *should* fix this problem. The battery drain should stop and the charger should fill the battery back with juice.

Now, I get that the battery heats up as it uses juice. But why is this the case when it gains juice from the external source? Once the battery is full, shouldn't there be a way for the software to use the juice directly from the external source, bypassing the battery all together? Or, if it uses the battery, why isn't there an efficiency method of minimal usage of the battery??

EDIT - Answer is found on this post: http://forum.ppcgeeks.com/showpost.p...72&postcount=6
EDIT 4/26/09 - Updating the radio from stock to newer radio versions reportedly help battery life. Telus seems to be the most popular: http://forum.ppcgeeks.com/showthread.php?t=46616