I am still focused on how to manage the battery life of my HTC Desire HD. The HTC Desire HD finished charging just before midnight, and I opted to turn of data, both WiFi and 3G, while I slept. I activated date when I woke up in the morning. I also decided to keep the data off, while I have my laptop on. Since both my laptop and smartphone are getting updates from the same services, it does not seem to make sense to keep both running. Having spend most of the day in the office, by 6:00 P.M. I still had six bars, which dropped down to five bars (50%) twenty minutes later. With minimal use data turned off, and just one phone call and a half dozen SMS, my consumption was much lower than the first day. It looks like this phone could easily get more than 36 hours of battery life with such use.
But that really defeats the purpose of getting a Android Smartphone in the first place. Trying to figure out how to manage battery life, I turned to the Battery University for tips. On Lithium Ion batteries one piece of advice was:
"Avoid frequent full discharges because this puts additional strain on the battery. Several partial discharges with frequent recharges are better for lithium-ion than one deep one. Recharging a partially charged lithium-ion does not cause harm because there is no memory. (In this respect, lithium-ion differs from nickel-based batteries.) Short battery life in a laptop is mainly cause by heat rather than charge / discharge patterns."
The site also says that "Lithium-ion does not need to be fully charged; a partial charge is better."
This advice solves most of my battery life issues. Top it off at night and keep data off. Do a full or partial recharge mid-day in the office. On days when I am on field the whole day. The fifteen hours on data I got on my first day, with a fair amount of use, should be enough.