[Touch Diamond, MDA Compact IV ROM Development] number16:
This started on suiller's ROM guide, but I feel it's really OT so I should take it outside.

I've had battery issue ever since I got the Diamond. With moderate use (maybe ~15-20min of call per day, email check every 30 min, moderate web browsing) the battery level can drop by ~ 15-20% per hour on average. This means the battery would only last 5-6 hours without charging, which is not good enough to last through a day.

I first looked at whether the phone has any serious battery drain application, and it doesn't. With BatteryStatus I see the battery drain is ~ 100-150mA with GSM on, BT on. When I'm downloading email, or browsing the web, it does go up to 200 ~ 300mA briefly, but that is only when it's transmitting / receiving data. In standby mode with screen off it drains less than 50mA. These numbers seem pretty typical from my experience.

And here's the weird thing - on a typical day, when I wake up, and take the phone off the charger, it can drop from 100% to 93% within 30 min. On the way to work, when I would browse the web lightly, it can easily drop from 93% to 80-85% within an hour. That's pretty bad battery life.

Yet there are instances when I've been browsing the web, or playing MP3, or using YouTube for a good 10-15 min, but the battery level would not drop.

I figure maybe the battery needs to be re-calibrated, so I decided to discharge the battery and recharge it. I know this doesn't help improve the battery life of LiIon batteries, but I was trying to recalibrate it.

What happened, when I was discharging the battery, was I found the battery drop was very quick from 100% down to ~ 50%. From that point on, the battery drop is much slower.

And from 50% to 25% the battery seems to last forever. The most interesting thing is with the battery down to 15%, I did a lot of 3G web browsing, listening to MP3's, turn wifi on, and that 15% of battery lasted a good 3.5 hrs with heavy use until it's so low the phone stopped working.

The whole discharging process ended up taking 10 hours, and that's with HEAVY use for the last 3-4 hours too. That's actually acceptable for battery life (not great, but at least it'll last me through a day outside with moderate use) and obviously doesn't jive with the 15-20% drop per hour when I'm operating in the 50-100% full range.

When I'm charging the battery, I also noticed the level went up from 0% to 70% very quickly ... pretty much over 40 min. BatteryStatus shows it's being charged at +600-700mA.

As the battery gets full, the charging is much slower ... BatteryStatus shows it is charging by ~ 100-200mA only.

With the battery level up to 99%, it took almost forever to finally get up to 100%. I think it took at least 20 min.

So after a full discharge - recharge, I used my phone as normal this morning to see if it's been calibrated, but nope. It still drops from 100 to 93% within minutes of doing virtually nothing, and easily drop to 80% after an hour ride to work.

Does your battery perform the same way? Should I replace my battery? Or is there a way to properly calibrate the battery?

btw location and reception has nothing to do with it. I have good to excellent reception throughout this test.