[askwhy]

Got a BATTERY ISSUE? Consider the following posts from the GSM EnergyROM thread at XDA. If seeing 'GSM' in this quote confuses you, just think of our '1X' CDMA mode, that's close enough. This isn't aimed at anyone -- it is for everyone.


Quote ShinySideUpAZ:

Some background. I have spent my career as a electronics design and manufacturing engineer. Currently I am a senior engineering director for a fortune 100 company.

Not wanting to get myself set up for a flaming, but here you go. When it comes to battery life each users mileage will vary greatly. There are cases where radio ROM will be a primary driver of the usage, but this is most often the exception.

The radio circuits in these devices are very efficient. When they draw the most current is when switching networks or negotiating connections. Dirty little secret: in the early days of the development, I was involved in this, of the cell network circuits a design criteria was placed on device manufactures to connect at all costs. If a connection was lost mid call, that's ok. The network owner is getting paid for each connected minute initiated, not minutes completed. Much of this is still resident in the core of the designs. As a consequence if you live in a spotty cell area where the phone is going to often be switching back and forth, say from GSM to 3G and back, you will see less battery life. This is why putting your phone in GSM only saves battery. 3G does not use a substantial amount of current above GSM. A little more, yes, maybe 3%, but not a great amount. When negotiating a new network connection a phone radio can consume 30% more power then when in a stable transmission. Additionally the radio ROM software determines when Hard Hand Off will be executed verses a Soft Hand Off when switching cell towers. In Hard Hand Off schemes the phone is quickly switched from one tower to the next, lower power at the cost of greater risk to cell drop. In Soft Hand Off, the phone may keep a connection to multiple towers in range during the hand off which results in greater power consumption for the benifet of a lower risk to cell drop. Signal Quaility algorithms determine which connection protocol has the most stable signal. If the signal quality trigger threshold in the Radio ROM firmware is too low the phone will try to switch too often either between service towers or connection protocols, GSM vs. 3G. You will almost always get longer battery life in rual settings because the density of available towers is less which reduces the impact of Soft Hand Off. These are reasons why radio ROM can be a battery drainer. The current hot topic for study by handset and circuit designers are new power supply schemes that address many of the power conversion ratios related to operation of the handsets in switching not only between transmission protocols, but also CPU/DSP clock idling schemes. There are a great number of patents and peer reviewed papers that have been published in the last 18 months looking at optimzing the power consumption of the devices when navigating a cell area and implementing diferent hybrids of the Hard/Soft hand off problems. In time, the hope is the impact of the Radios will be less and less as the technology reaches a plateau.

HOWEVER, the greatest consumer of power in any of our cell phones is the backlight. To that end Lumos Wizard is your best tool for staying off the cord. As an experiment two days ago I shut off Lumos, or more correctly didn't install it with the July 22 update, and monitored my battery usage at the end of the day. Now with a decent amount of calls and tweaking done when you get a new ROM I ended day one with 40% battery left. On day 2 I reflashed and also loaded Lumos Wizard. Day 2 had a basically the same level of usage. I ended the day at 76% battery.

The greatest effect from the ROM are services and process that make the phone wake up when we don't intend the phone to be doing anything but quietly waiting for a call or the next message. If you suspect a ROM power drain issue, give some context to the chef. Is the phone waking up when it shouldn't? Can a bump of the button cause the backlight to turn on? When a email or text comes in does the phone wake up and the backlight turn on? Does the execution of a internet push page make the phone turn on? Are you running S2U2 and do you have wake up on message turned on the the S2U2 settings, this will cause battery drain because the backlight turns on. BTW Lumos Wizard helps this because if the phone wakes up in your pocket or belt case the light sensor will be blocked. Lumos will assume you are in a dark room and set the backlight to minimum levels until the light changes.

I am indebted to NRGZ28 and the other cooks for the great work they do. They free me from the bordem of the stock ROMs. Sometime radio problems exist, but let's do everything we can to moderate our expectations and give them the time to do what we love, the generation of great fun ROMs for us to fill out time playing with.

Quote Phobos 512:

I think that we ought to just state that all [complaints about] battery life issues should be ignored because there is too much variability in usage and radio setups for the comments to be of anything more than an annoyance.

I am fairly sure nothing will stop the daily posts about battery life that fail to consider the many factors involved -- but maybe, one day...