After having read most of the battery threads on this site and some others, I have spoken with several people and have come to the following conclusion...
I WILL NOT LEAVE MY EVO PLUGGED IN OVER NIGHT, NOR ALL DAY.
If the person who posted the Kill-a-watt results, showing the Evo decreasing its charge as it gets closer to full, (ie draws less from the adapter) and then waits till the Evo drops to somewhere around 90% (the system determines battery charge by available power in the battery, not by 100% of charge) before starting to fill the battery up again. So, again, if the person who posted that is correct, which makes sense and someone gave it the term "floating charge" (think of carefully blowing a bubble to see how big you can get it without popping it, you would slowly blow it up, slowing down as it gets bigger, eventually backing off to breathe again, then start blowing again...), if this is correct, then the Evo Battery will be a worthless piece of junk in 8 months.
Lithium Batteries (of all kinds) are rated in life expectancy based on the number of "Charges" they are capable of incurring before the metals in the battery (lithium) break down and can no longer sustain a reasonable amount of charge. Many people have seen this happen with other devices (not all cell phones) after some time the battery fails to hold a charge, just ask anyone who is a heavy laptop user. A LiPo battery differs (mostly) from a Li-Ion battery in that they normally can accept x3 to x10 as many charge "cycles" before not meeting manufacturer specifications for the intended device. I have not see any Li-Ion batteries that do not fall into the 200-1250 charge cycle battery life range. most are 500 cycles and any over 800 usually proudly display it on the package (go find some Energizer rechargeables and look at the package for the # of Charge cycles they can handle, you will see the number clearly marked fairly large font if it is a higher number, if you are looking at older batteries (or the non-energizer/duracell brand batteries) you will either not find the number of charge cycles printed on the package, or it will be in smaller font AND be a lower number.
A friend of mine stated that the iPhone LiPo battery is designed to survive 2000+ charge cycles, hence why it is not a user serviceable part as the battery should outlast the phone, vs. the standard cell phone with a Li-Ion is only designed to survive 500 charge cycles (I did not say smart phone). I do not know the battery charge life cycle for HTC phones as it is apparent they are reusing the batteries in different models to save costs, I would guess it is not exceptionally high.
Ok, background info complete, time to make my point, so the rest of you can get on with your lives...
If the HTC Evo "Float Charges" your battery, and you plug it in at 9pm with 60%+ battery life and unplug it at 7am with 91%+ battery life, your battery will have been "float charging" after reaching a full level for approximately 8 hours, this will have killed your batteries life expectancy by 1-3 charge cycles. If you then do the same thing at work for 8+ hours, you will kill another 1-2 life cycles off your battery. IF the Evo only has say 750 life cycles on the stock Li-Ion battery (the one without the "foil" stripes) that people have gotten with all 3 models (HW001, HW002, HW003) (not saying everyone has this battery, just that it has been reported as having been shipped with all three model versions, so the model number does not dictate the battery that shipped with it), you have a maximum estimated time of 375 days before your battery will fail to hold a charge forever more. The minimum is much scarier, as it will only be 150 days before your battery starts to fail to maintain a constant level of charge. This math is based off you doing the same thing every day, 7 days a week, which I do not think anyone on this planet actually does, except maybe a 1 week old baby... and even they will change their habits before 375 days pass... to make the math worse, if you use a life expectancy of 500 charge cycles you are looking at 100-250 days of battery usage before needing to replace it.
Please feel free to argue and curse me, and to find factual proof against my argument, but I for one will be charging my phone, only when I am conscious and capable of unplugging it immediately when the green light comes on, and only when the battery drops below 20%.
peace out.
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