Charging a 3500 mAH Extended Life Battery on an EVO 4G

I am currently considering the purchase of a 3500 mAH battery for my EVO 4G. After reading numerous posts on forums, I need some clarification. 

Background:
First, many users have indicated their belief that the phone senses when it reaches a 100% charge and then operates on battery even if still plugged into a charger. They further assert that this explains why, when left on a charger overnight, the phone often seems to drop 8% - 12% in the first 20 minutes of use and that this phenomenon is actually the phone reporting its true charge after the first 20 minutes of use when charged overnight as described. The suggested workaround is to "top off" the charge until the 100% charge (green LED) is reached again and then unplugging the phone ASAP. (I suspect the unplugging the phone just as soon as it reaches a full charge is perhaps important to fully charging the phone under all circumstances.) 

Next, I have read other users' posts by users who have purchased 3500 mAH batteries. Many of them contend that when the phone initially reports a 100% charge, the phone is actually reporting a full charge to 1500 mAH - the 3500 mAH still needs to be charged for at least an additional few hours. 

Requested clarification:
In light of the information outlined above, I wonder if it is even possible to fully charge a 3500 mAH extended life battery in an EVO 4G. Once the phone senses a 100% charge, would it just go to battery operation? Will the phone sense that a 3500 mAH battery needs further charging? Is the charging circuit, sensor, or whatever configured to charge only to 1500 mAH? Will the charging circuit, sensor or whatever allow further charging? 

I would deeply appreciate hearing from anyone who has direct experience using any extended life battery in an EVO 4G and are willing to give me the benefit of their experience! 

How does the voltage differ between the stock OEM battery and a 3500 mAH battery? How does the phone know?

I found this post in the EVO 4G Accessories forum:
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I usually pay attention to the voltage rather than the charge light. If you haven't yet, get a battery application or a system info app that gives you info on the battery and voltage. Typically when the battery is full the voltage will be close to 4,200V. When the battery is halfway, the voltage is around 3800v. When mine is full, it's typically around 4,19x volts.

Here's a pretty helpful description of someone's test from the xda forum:

My experience.
Charging from empty.
After 1:41h evo said battery is full. With 3,976V. But charging still continued. After 2:40 charging finished with battery on 4,121V. And startid cycle. And after 8h is battery on 4,199V. Should be full if full battery is 4,2V how somebody said. Only time for full charging is short..only 2,75h x 800 mA is 2200mAh. But battery shows 4,199V and should be full..so...i dont know conclusion :-)
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This is a lot more informative and to the point than whimsy about "magic smoke." It's not that I lack a sense of humor  rather, it's that I needed information not condescension. Thanks for your time and have a nice day.