[HD2 General] kilrah:
With the HD2's pretty short battery life compared to my previous HTC phones, and also as I was a bit bored :p , I decided to have a look at how much the different systems drain in the HD2, and did some tests.

So for anyone interested, here are the results:

Base consumptions:

(pick the one that suits your situation)

Standby, phone on, WIFI+BT off, no connections active: 5mA

Processor running idle, screen off, connections as above: 55mA

100% CPU usage (Coreplayer benchmark), connections as above: 315mA

USB connected, connections as above: 125mA

Additions:

(add this to the base one depending on what you have on)

Connections:

BT on, idle: +1mA

Wifi on, idle: +5mA BUT!! If you enable wifi during standby (with BsB Tweaks or the WifiNoStandby CAB), the processor does NOT go to standby

anymore, so the base needs to be the 55mA above!

Connected to EDGE, idle: not measureable

Connected to 3G, idle: +4mA

Beware those 2 will occasionally and unpredictably send data every now and then, so this doesn't necessarily mean much.

BT transfer (file copy through ActiveSync, 120kB/s, CPU usage ~2%): +80mA

Wifi transfer (file copy with Wifi Remote access, 1MB/s, CPU usage ~3%): +200mA

EDGE/3G transfer: Pretty impossible to measure due to so many variables, but can be extreme (total current consumptions of 850-1150mA, so very approximative 500-800mA draw from the data connection during page loads are common!), and leads to most of the energy draw when using the net a lot. EDGE uses more power than 3G, consumption is higher when network coverage is lower, bad network throughput or congestion also mean lots of retries/overhead and less effective data transfer, using power for a longer time until the data is finally there.

Memory access

(large file transfer):

Internal read/write through ActiveSync (speeds 2.5 / 2.1 MB/s respectively): +20mA / +130mA

Card read/write through ActiveSync (speeds 3.2 / 2.7MB/s respectively): +25mA / +40mA

Card read/write in USB disk mode (speeds 7.5 / 5MB/s respectively): +40mA / +45mA

Backlight:

10%: +65mA

20%: +78mA

30%: +90mA

40%: +105mA

50%: +121mA

60%: +136mA

70%: +154mA

80%: +170mA

90%: +190mA

100%:+210mA

GPS:

+95mA

Flashlight (with HTC Flashlight):

Level 1: +32mA

Level 2 (same as camera flash on): +107mA

Level 3 (same as camera "bright flash during shot"): +530mA

And remember the battery capacity: 1230mAh

So with this you can calculate your battery life for various activities. For example:

- Playing a video with full backlight: Let's say the video is well encoded (30% CPU use, for example 720x400 1Mbps DivX), that's about 150mA base, + 210mA backlight = 360mA, resulting in about 3h20 battery life.

- Same at night with only 40% backlight: Life goes up to about 5h!

- Wifi during standby for an 8h night, or a program that somehow prevents the phone from entering standby: 60mA or 55mA respectively, draining about 40% of the battery during that time.

- GPS program, with 70% backlight: Let's assume 150mA for the processor as it has some work to do, 90mA for the GPS, 154mA for the backlight = 394mA, or 3 hours.

- Music through wired headphones, screen off: the 55mA base plus a little 5mA as MP3 decoding is nothing for the CPU = 60mA or 20h.

- Same with a BT headset, with about half the BT bandwidth: 60+40 = 100mA or 12h

etc.

Charging

[EDIT 14.04.10]

This is now a dedicated section as I did some more thorough charging tests.

So, as some of you might know, the HD2 has 2 charging "modes".

- One is USB, that is used if the phone is connected to a PC, or an unknown device. In this mode, the current the HD2 will draw from the port/charger is limited to approx. 470mA, to stay within the maximum of 500mA a USB port can supply.

- The other is "dedicated charger", which is recognised on the original HTC charger (and some others, it's becoming a standard for a "dedicated charging USB port") by shorting of the 2 data pins of the USB connector in the charger.

USB charge

Important to know, during USB charge, the phone will NOT go to sleep, as it's supposed to be connected to a PC, and be running either ActiveSync, Disk drive mode, or modem, and in all 3 cases would be expected not to shutdown. So not only the current supplied to the HD2 is low, but the phone draws some of it for itself, leaving very little for actual charge - so expect loooong charge times.

USB charge with screen on (backlight dimmed, 10%): 285mA

USB charge with screen off (standby): 345mA (which shows the processor still runs and draws the "base USB" current)

Dedicated charger

When used with a charger that has the 2 USB data pins shorted, such as the original charger, the HD2 will draw a current that is proportional to the voltage on the USB power lines. To measure this I have used the original supplied USB cable, a variable regulated power supply, USB socket (with data pins shorted), and 2 meters for voltage/current. Voltages are measured at the "PC" end of the USB cable, so not taking account of losses in the USB cable. Will talk more about this later on.

Current vs Voltage diagrams are attached. Charge current is proportional to voltage, linearly until it reaches the max charge current, approx 830mA. This was measured so that the only draw is charge. If the phone is turned on while at max charge current, it will draw extra, until it reaches about 980mA, and will then stop to respect the 1A rating of the stock charger.

Now, to the influence of USB cables. I initially had some trouble with inconsistant numbers, phone only drawing 670mA from the stock charger, i.e matching neither the ~350mA from USB, or ~830mA from stock charger in "normal" condition. Turns out that to make it more convenient on my workplace I was using an USB extension between charger and HD2 cable. It was a $2 extension I bought on Dealextreme. Removing it solved the problem... and after making those measurements I poked with it again. Turns out that at 1A current, the voltage drop in the extension (which by the way isn't longer than the HD2's USB cable) was 1.8V! Yep, nearly 2 Ohms for a 1.5m extension! Couldn't believe it.

I have a cheap Chinese microUSB cable that wasn't as bad,but still significantly more resistive than the stock one, hence me noting I used the stock cable for my tests. So, quality of the cables, extensions, adapters IS important! Note the phone correctly reaches full charge current a little bit under the 5V USB spec, so everything is well tuned.

Now, important to know, Most 3rd party chargers will not have the 2 USB data pins shorted, and will thus result in the same behavior as mentioned under USB charge, the processor will also be running continuously drawing the "base USB" current.

It is often possible to modify 3rd party chargers by opening them and shorting the pins, speeding up charge. The voltage/current curve behavior is actually helping there, because thanks to it if the charger is overloaded its voltage will most likely fall a bit, and the HD2 will thus draw less and find a nice balance point. This DOES NOT mean there's no possiblilty of damaging the charger, but all 3 I modified did well. One that was really weak resulted in not much more current being drawn after the mod than before (i.e voltage fell very low, approx. 4.4V), however the gain from not having the processor running like in USB mode still sped up charge a little.