[EVO 4G General] lovethyEVO:
50% loss over 8 hours of near constant use (my awake time shows that it did manage to sleep somehow even though I streamed pandora constantly) on any battery (extended or not) is actually a good thing as it shows that even with the phone fully bogged down (almost all radios on) it can last a full work day (which is what most people are concerned about).

I still believe the evo does not charge the batteries correctly and it is not solely related on the absence of a trickle charge.

Again, from my observations over the course of the past three weeks. I started with what my battery was calibrated to according to the phone. Let it drain down to about 15% (according to the phone) and wiped the battery stats and did a different charging method from the htc "rain dance".

Here is where my opinion of the evo not charging properly comes into play.

From 15% to 100% charge (charged while phone and screen are on to monitor voltage, temp, mA draw, etc.) took about an hour +/- a couple minutes. As soon as the led turned green (yes, I literally sat at my phone watching the percent slowly rise) I unplugged the charger and noted the resting voltage level and percent (according to three seperate battery status applications). Once noted, I powered down the phone. After the screen completely shut off I removed the battery and tested the voltage. I did this for my own information because I wanted to verify the phone itself was actually reporting the voltage levels correctly. It was.

Now, recall that I had just charged the phone to 100% and had wiped battery stats prior to charging.

Replaced the battery back into the phone and powered up. Normally people see a jump in battery percentage when they power down and back up. Not in my case. To my amazement, the evo reported my battery as being at 78% charge level. So I went from being 100% charged down to 78% percent charge all from powering down, removing the battery, checking voltage, and then replacing battery and powering up. Time to power down, remove, check voltage, replace and power up is somewhere around the one minute mark +/-.

Again, referencing the link I provided earlier about charging li-ion batteries, the evo seems to skip stage 2 of the charging process which usually results in about a 70% charge (according to the link).

Charged it again from the 78% mark to 100% and the charging time took just over an hour to get back to 100%. Same routine, check voltage on phone, power down, remove battery, check voltage on mmeter, replace battery, power on, check levels.

Second time around I dropped from 100% charge to about 89%. Voltage levels were always accurate. Charged again and took about another hour +/- and finally achieved a charge to where it would not fall or rise between a power down (97% seems to be my cap which is fine since I don't want to truly charge the battery to 100%).

To test the discharge rate I tried my best to keep the battery running condition identical for each discharge run.

I monitored the battery temp, cpu temp, battery voltage, amp draw, and cpu load.

Streaming only pandora and nothing else I usually managed to keep the amp draw to around 300 - 360mA with the screen on. This was my way of measuring the discharge rate without access to equipment that could give the battery a steady discharge load.

Every time the percentage dropped one I would note the volts, temps, amp draw and cpu load. Across the board temps and cpu load remained close to constant as the phone wasn't doing too much multitasking.

At this point, I have about 4 full voltage readouts from 100% down to 15%. Without wiping battery stats, if I charge the phone with my method (charge to 100%, power down, remove battery, replace battery, power up and recharge) my past voltage readouts coincide with my battery readouts on the phone (87% falls within a certain voltage range and so on) but if I just charge the battery until the phone says it's 100% then the readouts on the phone no longer fall within my past readouts until I go back to my charging method. This tells me that if I let the evo charge the battery the way it is programmed to (hardware or software) then it is not actually charging the battery to its full potential (not necessarily 100%).

Across the board the cpu load and the temps rarely drastically changed as it wasn't running multiple tasks at once. This is just my own observations and tests that I did/started doing for my own intellectual reference.

I have done the same charging method with my wife's evo and stock battery (1500 htc oem). I wiped her stats but only managed to get two full voltage readouts with her phone. She has stated that her battery does last longer than before and she is only rooted to remove bloatware. She is running stock rom, stock kernel, no task killers, no memory managers, and her radios and settings are close to mine (she gets more mail and facebook notifications than I do).

Again, this is just my opinion and personal observations. I did this solely because I got tired of having to constantly turn things on and off just to use them. My past phones never had this problem and I don't think the evo should have to be babied just to get good battery life. I still believe it all lies in the charging system of the phone and not necessarily the battery (extended versus stock).