[Optimus One, P500, V General] mmarz:
Part 1

Intro:

I took my Optimus V and spliced in a multimeter between the battery and the phone. All it took was double sided tape and tinfoil. With the battery installed in the phone, the foil directs the positive terminal of the battery out of the phone, through a multimeter, and back into the phone through a second piece of foil that is separated from the first with double sided tape.

This enabled me to monitor the actual battery draw. I installed various roms and monitored the battery usage under certain conditions. I focused on the lower end of battery usage (airplane mode, stand by, under-clocking) because that is the focus of most smartphone users, getting the most battery life. I had a resolution of 1mA. So keep that in mind when looking at the results. A value of 2mA means the actual value might be 50% more or less.

Setup:

Each rom was a fresh flash. The only apps installed were google's. Airplane mode was toggled in order to remove the effects of the 50% Time Without Signal issue. The Rodimus rom had setCPU added to control CPU speeds. Besides changing the relevant settings, nothing in the system was touched. A steady 3G and CDMA signal was available during testing. A Wifi signal with WPA2 protection was used in the Wifi tests. A google account was also added to all the roms and background information was left enabled. Syncing was turned off. All of the values measured fluctuated somewhat during testing. Approximations had to be made as to the average stable values.

Roms Tested:

Stock

Rodimus 20/03/2011

Zefie's CM7 01/03/2011

aospCMod CM7 24/03/2011

Testing Conditions:

Powering on

Airplane Mode - Standby - Underclocked to 122MHz

Airplane Mode - Screen Brightness 0%/100%/50% *

Wifi - Standby - 122MHz

3G - Standby - 122MHz

No Data - Standby - 122MHz

Wifi - Standby - 600MHz

3G - Standby - 600MHz

Airplane Mode - Standby - 600MHz

Wifi - 600MHz**

3G - 600MHz**

Airplane Mode - 600MHz**

*CPU set to 600MHz

**Unless noted otherwise screen brightness was set to 25% and the phone was left on its homescreen.

***Because of a lack of CPU control, the stock rom could only be tested at 600MHz

Results:

50% Results:

I also tested the 50% Time Without Signal issue using Rodimus. Airplane mode was not toggled after a fresh install. 50% issue was confirmed. Wifi was then setup and then put into standby mode for the measurement. Then Wifi was disabled and 3G automatically connected. The 50% issue was again confirmed to be in effect. The phone was then put in standby mode for the 3G measurement. Data was then disabled and put back into standby for the last measurement.

Wifi: 5mA

3G: 300-2mA****

No Data: 2mA

****When 3G was enabled and the phone put into standby, the current draw would fluctuate from 2mA to 300mA every few seconds. This was not seen in tests where airplane mode was toggled on and off after boot.

Conclusions:

At first glance there does not see to be much difference between the roms. Remember though that all of the 2mA values have an error of 50%. So there could be a 3 fold difference between some of those values. If I had a more sensitive multimeter, we could get better results.

One notable difference is between the roms when using Wifi on standby. The stock rom and Rodimus both draw significantly less power than the CM7 roms. This seems to be an unresolved bug with CM7. Also worth noting is that 3G draws significantly less power than Wifi regardless of Rom. Keep in mind that no data is being transferred while the tests are occurring besides whatever the background data uses.

It looks as though the 50% Time Without Signal issues does effect battery life when on 3G. The phone appears to be doing some activity every few seconds. Take note that I only tested it on Rodimus.

Using a current draw of 3mA, the 1500mAh battery could last as long as 500 hours. Of course, even in standby and underclocking, the current draw will randomly jump to 100mA every now and then on all of the roms. A more practical estimate at the battery life is 100 hours. That gives an overall average power draw of 15mA.

I was hoping underclocking would show a significant decrease in power use, but my resolution was not good enough to pick up a difference. I'm sure an advantage still exists, but I can't prove it with the equipment I have. The effects seem to be limited to less than 1mA. This is worthless when using the phone, but when in standby, the savings could be significant.

Hopefully these values will help you out as well as the developers. Let me know your thoughts. Note that all of these values are current draw directly from the battery. Another user on Howard forums tested the draw from the USB port which occurs at 5V and doesn't account for the loss due to stepping down the voltage.

Winners:

Leaving 3G on during standby - No clear winner among the roms because of testing equipment limitations but by far better than leaving your phone on Wifi

Airplane mode during standby - No clear winner again

Leaving Wifi on during standby - Rodimus

Not in standby but idle - Stock rom