Several users of the HTC EVO 3D have reported charging and overheating problems with their new phones, including abnormally high voltage while charging and drastic reductions in battery life after only one week.
One user claimed that, after noticing unusually high temperatures while charging his battery with the supplied HTC charger, he investigated the voltage and discovered that his phone was charging at 4.385 volts. The maximum voltage that the stock EVO 3D battery can safely handle, however, is only 4.2. After speaking with an advanced technician at Sprint, he was told that this is a known issue and was encouraged to return his phone to his original place of purchase.
Another user reported that his EVO 3D became very hot while unplugged, even after killing all background tasks and ensuring that his wake time was normal. His battery was then fully depleted after just three hours of use in a good signal area, which could be indicative of damage to battery cells caused by high voltage.
Battery issues such as these should never be taken lightly, as they can sometimes result in injury in the most extreme cases. And while Sprint is reportedly telling individuals that they know about the issue, no official announcement has been made yet. It is also unclear whether this is a hardware issue or one that can be solved by a software update.
In the meantime, I encourage you to download a battery monitoring app from the Android Market, such as Battery Indicator, to monitor your voltage and battery life if you notice any abnormalities. We have reached out to Sprint and HTC for comment and will report back once we have received a response.[Android Forums via Phandroid]
Update 7/08: You can read the official responses I received from HTC and Sprint here.
Update 7/18: HTC reached out to us again to clarify that the batteries used in the EVO 3D are actually 4.35 volts, not 4.2. Additionally, HTC acknowledged that they have finally looked into the issue of overheating but have still not been able to replicate it themselves.