I have been rooting for years but I never bothered to really mess with kernel settings to increase battery life. All I'd do is over clock or under clock. What do you guys do to increase battery life? Like for example, lower voltages? I have no clue exactly how this works. I'm kind of tired of carrying 2 spare batteries around lol I'm on Franco's kernel with the hot plug enabled from his app but I might switch to imo's. Anyone wanna be kind enough to help me out please?
I just got a 200mah battery and its animal.
Before I used APEX kernel and took the usual steps, dimmed the screen etc.
Thank you for the response. I'm sorry, I should have stated that I'm on the CDMA version lol
I've been considering a custom rom/kernel and reading up on them a bit. I'm pretty much a n00b, so maybe this is nothing new to you, but it seems that controlling kernel wakelocks and specialized cpu governor settings + undervolting are the main things that increase battery life. I think minimizing unnecessary wakelocks seems to be the main key.
For the most part, battery drain comes down to two issues:
1. Screen use (not much we can do here)
2. Radio use (which tends to wake up the phone unnecessarily, I think)
I think the radios -gps/voice/3g/4g - is what causes unnecessary wakelocks on stock rom/kernel - as I get virtually no, nada, zip, zilch, zero sleeping drain in airplane mode.
If your battery drains 1%+ an hour just sleeping, it can add up significantly. Even when things are turned off, they still sometimes cause wakelocks. Take NFC for example, I just read in a forum post that it was causing wakelocks even when turned off.
Question
Do you guys think since in AMOLED displays the black color is essentially the pixels being turned off, having a black wallpaper uses less battery? because each time I check my battery usage I see that my display is always on top, and I have this theory can anyone confirm it or correct me if I'm wrong?
This guide is not meant to be as a whole and is not meant to be followed from beginning to end. There are several recommendations based on my own experience, some of them will give you big battery savings, some of them minor ones; I tried to recopile every config that helps to save battery, but every config is not suitable for everyone. (I´ll point it at the beginning of every section in bold blue).
You'll need a Rooted Galaxy Nexus, with a custom ROM and a custom Kernel.
The custom ROM will give you the ability to make a deep configuration of the device in terms of options. I'm actually using Liquidsmooth v1.25, but AOKP, CM9 and SlimICS have the same options (if not more) than my actual.
Some custom Kernels will give you the ability to change the CPU frequency and voltage, kernels are the main reason of some drainings or fantastic battery life, choose wise.
The normal Galaxy Nexus battery life is about 4 hours screen time. If you are not achieving this, the main reasons could be:
1. Some apps are draining your battery due to a continuous use (no deep sleep or continuous wake ups).
2. Screen too bright.
3. Bad kernels with draining problems.
4. Weak signal connections.
This guide is wrote by me, a simple user that is sharing his own experience of the last 4 and a half months with the device. Some statements may be wrong. I'll appreciate any positive recommendations in order to improve the guide and help the rest of the community to achieve the best battery life the device can give us.
I'm using actually Liquidsmooth v1.25 and PopcornKernel, in a GSM GNex with standrad battery (1700mAh), and I'm getting this results:
{
"lightbox_close": "Close",
"lightbox_next": "Next",
"lightbox_previous": "Previous",
"lightbox_error": "The requested content cannot be loaded. Please try again later.",
"lightbox_start_slideshow": "Start slideshow",
"lightbox_stop_slideshow": "Stop slideshow",
"lightbox_full_screen": "Full screen",
"lightbox_thumbnails": "Thumbnails",
"lightbox_download": "Download",
"lightbox_share": "Share",
"lightbox_zoom": "Zoom",
"lightbox_new_window": "New window",
"lightbox_toggle_sidebar": "Toggle sidebar"
}
SCREEN
Due to the big screen, this is one of the elements of the device that affects in a major way to the battery live. (Great Savings)
It has been checked that black themes have a great impact on the battery due to the fact that one black pixel does not consume any battery.
Some apps have a black theme option on them, if you choose it you will save some battery.
On the other hand the brightness is the other part in the screen that has a big impact on the battery. In a logic way, less the brightness more the battery life. (Greatest Savings)
Now the latest ROM's have a new amazing feature, we can change the interval the sensor works to achieve the ambient light, reduce the brightness minimum value (that's by defect way too high in low light conditions), and customize your prefered light levels (that are too way too high in default configuration).
By reducing the sample interval sensor a bit and reducing the minimum value a lot we can achieved abetter battery life in a great manner.
Also adjusting the light sensor levels to a more reliable one's that are by far lower than the default one's we'll achieved a more optimize system that consumes less battery.
Note: This are my actual, after 2 weeks of adjust, values but I'm still working on them, they are no 100% reliable.
CPU
The CPU is a great beast. In terms of battery is well adjusted, by as always, we can achieve a personal optimized system (this is Android, yeah!) that will balance performance and battery life. (Great Savings Underclock and Undervolt combo).
A very good speed and fluidness can be achieved with a very good optimized and well balanced performance-battery friendly system.. and yes, with the last advances in kernels and ROMs, we can have a perfectly smooth system with a top speed of 1000Mhz.
In the other hand Undervolt will help us to achieve a cooler system with some battery gain. With Undervolt we´ll limit the max. value of the Voltage for the specified frequency, if we have a kernel with Smartflex, this one we´ll allow lower voltages depending on the power need of the CPU.
Two important things:
1. It has been tested that the 700Mhz frequency is prefereable over the 300Mhz one, due to the drops on frequency signal of the phone.
2. Undervolt values are not the same for everyone, it can oscillate depending on the individual CPU. When I UV I always test my system with an Stability Test app.
Connections
GNex is a phone...also.. well, it's a super computer with phone capabilities. Due to the "always connected" philosophy the optimal baseband will save a lot of battery. An optimal Baseband and Radio (region optimized) will require less power and time to connect to the antennas and will have better connection always (less power irradiated). (Medium savings).
The Radio should be updated and region optimized, there's a magnificent post made by josteink that explains all the details concerning the Radios with links to every one available.(GSM)
[Radio] (GSM) Galaxy Nexus I9250 Baseband dumps collection & discussion
European Radio Recommended: XXKK6 (XXLA2 is giving too high "Phone Idle", resulting in drain problems)
For the CDMA version there is another magnificent post by ready5 with a compilation of every RADIO for the CDMA version of the GNex.
(CDMA) [RADIOS/HYBRIDS]*UPDATED* 4.0.4 FULL 2/6/2012 PLUS FRIED RADIO Halp!
In the GSM version on the other part the 3G, HSPDA consumes great great great battery juice. If you are not in WIFI and are not using the data connection, a great way to save battery life is changing from HSPDA or 3G to 2G networks (this is really noticeable if you travel a lot by car or train, cause you are continuing connecting a reconnecting from different radio antennas).
There's some ROMs as Liquidsmooth that allows when you are not on WIFI and after an specified delay, to change to 2G automatically (or low consuming) networks when you have the screen off. This is a great way to save battery when you are not at home, reducing the standby drain of the phone outdoors.
.
The automatic 2G when sleep is a main function of Juice defender. Thanks to a1exus for recommendation.
In the CDMA version the LTE consumes also great great great battery juice. If you are not in WIFI and are not using the data connection, a great way to save battery life is changing from LTE to 4G networks (this is really noticeable if you travel a lot by car or train, cause you are continuing connecting a reconnecting from different radio antennas).
Thanks to thenickisme for this!
WIFI
Wifi has a crazy history on the GNex. After talking and talking, posting and posting, it has been tested that WIFI always on while sleep is the best way to achieve a longer battery life. (Medium savings).
Also the new ROM's have amazing feature that change the WIFI interval (we normally stay at the same WIFI always), increasing the value will save batterty life reducing the continues scans that produce the WIFI Always ON requirement.
Services and Apps
The best thing of Android is that we can configure anything, one of the best and underestimated feature is the Freeze or Service Uninstall. We did it before in Windows and we can do it now. Through the Apps section in Preferences or the mythic Titanium Backup we can disable or uninstall an internal function of the systems that is normally used, giving more resources to the system and in some cases, saving some battery. (Low to Minimum Savings).
There are some ICS functions that no everyone uses. For example, I don't use any Bluetooth, NFC, Google Voice, Google Search or Speech function of the system, freezing or uninstalling them will optimize our system giving some battery juice.
Note: This is a dangerous thing if you don't understand what you're doing. Make always a Nandroid before Freezing or Uninstalling an essential function, just to be cautious.
According to the Apps we have to take in account the Background Syncing or Sync Interval, most of the time the apps don't need to be synced every 5 minutes, like weather, if we make longer updates we'll achieve a good saving battery related. (Great Savings if many apps with many connections).
Widgets, 5 homescreens full of widgets updating in real time could be detrimental to the battery live, take care when adding widgets and as said in the previous paragraph, change every widget preferences to update in longer times than usually they have by default. (Great Savings if many apps with many connections).
Bad Apps are the one's that not allow our device to deep sleep or wake up continuously our GNex. There are several on the market, Readability for example is a new one that wake up continuously our device attempting to download new articles, on the other part, some time ago Widgetlocker had some problems not letting deep sleep the GNexus (don't know now). (Great Savings if there is an apps giving deep sleep or wake ups problems).
Pointing on this, the best way to know if any app is not behaving well in the system is through 2 apps:
- BetterBatteryStats, that will look for any wake up of the device while sleep.
- CPU Spy, that will tell us if the device is deep sleeping ok or not.
Other things
There are other things that will help us in a great or minor manner to save battery life.
Sync Data usage (Google services like contacts, bookmarks, etc..) consumes battery, if you limit this usage, you´ll gain some juice. The new ROM's in the Powersaver tag will allow you to limit this sync usage. (Low Savings).
The Dial Pad Touch Tones and Vibration affects battery also (yepp it's true, and in a great way!), disabling this features will give you some extra battery juice. (Low to Medium Savings with combo sound plus vibration).
The Google Location services and Backup&Reset Data consumes great battery also, limiting this services will gave you some extra juice. (Medium Savings).
The last little thing that will help you save batt life will be the Automatic Date&Time option, disabling it will give you some extra juice also. (Lowest Savings, practical minimum).
Live Wallpapers, they are very nice but will drain your battery quickly. Static Wallpapers are preferred, and if posible, dark ones. (Medium to Great Savings).
Experimental
This are new tweaks that normally appear in new/advanced kernels, his use according to battery save is still not really tested or can have a detrimental on the physical conditions of the device/battery. Use them with caution or if you really know what you are doing.
[MOD][KERNEL]Battery Life eXtender (BLX), this is a tweak created by the popular Ezekeel and in his owns words: "Older types of rechargable batteries exhibited a 'memory effect' which made it neccessary to completely charge/discharge the battery when using to prevent degradation of the capacity. Modern Lithium-Ion batteries like in the Nexus S do not show this problem and thus it is not necessary to use the battery in complete (dis)charge cycles. In fact on the contrary, it is commonly accepted that both very low and very high charge states accelerate the degradation of the battery capacity (that is why you should store Li-Ion batteries at around 40% charge).
While a low charge state can be simply avoided by charging the device more often, the battery in the Nexus S by default is charged to around 95% capacity and I could not find any app or tweak to stop the charging at a lower capacity. Thus the only way was to use the manual override and pull the cable which is annoying since one had to monitor the charge state." (Unknown Savings).
Galaxy Nexus is charged by default to the 96% of this capacity, with this new tweak you can gain this 4% (don't know for sure if you can get the 101%) of battery life, in 4 hours screen time, more or less 10 minutes, but it can be detrimental on the long way to the battery physical life.
You can found this tweak in the last nightly of Franco's Kernel, and can be activated via his own app.
You can find more information in Ezekeel post here at XDA.
[MOD][KERNEL]Undervolt of IVA and CORE Voltage, new patches let undervolt the IVA (hardware media decoder) and CORE (GPU Voltage), I'vce been playing with this all the day and I've managed to undervolt a 15-20% de original frequencies. (Unknown Savings).
I understand that with this we are limiting the maximum voltage they can use, letting them to use lower ones according to GPU load. I'm not sure at this (GPU uses smartflex also ¿?) but with a descent of 20% on the voltage could result in longer battery life while playing games or seeing movies.
I'll try further undervolts, but this are my actuals on a stable system.
You can play with this voltages via the last nightly of Franco's Kernel, and via his own app.
Take care playing with this, could result in system instabilities, reboots, freezes, etc.
Links of interest
- BetterBatteryStats, A high battery drain is often a limiting factor for a great user experience.
With BetterBatteryStats you can analyse the behavior of your phone, find applications causing the phone to drain battery while it is supposed to be asleep and measure the effect of corrective action.
- CPU Spy, This is a simple app to display the time the CPU spends in each frequency state. This can be a useful tool in diagnosing battery problems or tweaking your over-clock settings.
It also displays the current kernel information.
- StabilityTest, StabilityTest is a stress-testing tool for android devices with error reporting.
StabilityTest is a CPU, GPU, RAM/memory stress-testing tool for your device, whether stock and unrooted (limited functionality) or rooted and overclocked with SetCPU, SetVsel or similar tools.
Extended Battery
At the end, the best way to extend the battery life is with an Extended Battery, they are not very expensive and only increase a little bit the thickness of the device. They can be bought at several places through the typical places as Ebay, Expansys or Amazon.
Important: Take in account that the CDMA and GSM versions have different batteries and they are not compatible, normally the GSM one is longer and black and the CDMA is wider and blue.
Borrowed from Buddy Revell
Calibration
Once a month we´ll have to calibrate our battery so that the information to be shown on screen is accurate and true. The steps are as follows.
1. Charge the Nexus until the indicator shows us is 100%.
2. Disconnect it and let it discharge until it turns off by herself.
3. Then load up fully charged. Note that this state is reached after one hour approx. since it shows that is already loaded.
Note: There are several apps in the Market that help calibrate the battery, although I have heard that in ICS Google has changed the file location does. Log of our battery so many of them may not work well if they are not updated.
great post especially for a new gnex user. will look through these options thoroughly.
Very nice. Thank you! Took a few suggestions.
Looks like I've got some work to do =D
Sent from my Galaxy Nexus using XDA
edited out
Cool story bro! Lots of good tweaks to maximize battery.
Sent from my Galaxy Nexus using xda premium
What rom is that? You should state that ...
Awesome. Those custom backlight levels are going to save a good amount of battery. I tried using a filter, but it made using the phone in sunlight impossible.
It's working inside well and based on what I see from the custom levels, it should have no issues once I take it outside.
As for the underclocking, comparing iOS and Android isn't fair. iOS has an advantage with its closed ecosystem. I personally overclock the GNex to achieve the same snappiness I had on my iPhone 4S. Sure the underclocking will save battery, but I might as well be using an older phone if I'm going to underclock.
When it comes down to it, everyone's battery is >50% screen consumption. Your custom levels are going to tremendously increase battery life.
gogol said:
What rom is that? You should state that ...
Click to expand...
Click to collapse
It's in my signature, Liquidsmooth v1.25.
myrdog said:
Awesome. Those custom backlight levels are going to save a good amount of battery. I tried using a filter, but it made using the phone in sunlight impossible.
It's working inside well and based on what I see from the custom levels, it should have no issues once I take it outside.
As for the underclocking, comparing iOS and Android isn't fair. iOS has an advantage with its closed ecosystem. I personally overclock the GNex to achieve the same snappiness I had on my iPhone 4S. Sure the underclocking will save battery, but I might as well be using an older phone if I'm going to underclock.
When it comes down to it, everyone's battery is >50% screen consumption. Your custom levels are going to tremendously increase battery life.
Click to expand...
Click to collapse
Thanks
With the iPhone comparison I just tried to emphasize that sometimes underclocking results in the same snappiest system, but yes, is a little unfair though (but I can assure that with the latest Kernels and ROMs that have been released, I have a totally fast and smooth system with only 1000Mhz).
Well done good job
Good guide. Rather than seeing multiple thread's about awful battery life its nice to see people talk about how to maximize their battery life
Sent from my Galaxy Nexus using xda premium
Good guide—thanks for taking the time to make it—but along with it’s very good parts, it has quite a few inaccuracies, is misleading in some places, doesn’t fully explain the ramification of making many of the changes that are proposed and makes questionable changes for very little gain. Amongst other things, my major issues with it are:
You wrongly assume a device that does not get four hours of screen time is not optimized—this would be incorrect as one can get four hours of screen time with the stock ROM and default configuration.
The stock ROM does not allow you to customize the backlight and CPU—so you should point this out.
It’s condescending to the iPhone (while the GN might be better in many ways, patronizing another device has no place in a “guide”).
BinkXDA said:
Good guide—thanks for taking the time to make it—but along with it’s very good parts, it has quite a few inaccuracies, is misleading in some places, doesn’t fully explain the ramification of making many of the changes that are proposed and makes questionable changes for very little gain. Amongst other things, my major issues with it are:
You wrongly assume a device that does not get four hours of screen time is not optimized—this would be incorrect as one can get four hours of screen time with the stock ROM and default configuration.
The stock ROM does not allow you to customize the backlight and CPU—so you should point this out.
It’s condescending to the iPhone (while the GN might be better in many ways, patronizing another device has no place in a “guide”).
Click to expand...
Click to collapse
Thanks, but the guide tried to be a compilation of many procedures that would give you a longer batt life. Some of the recommendations give you maybe 4-5% more autonomy, some of them 0,5%, don't know because I'm not an engineer and don't have the tools and time to measure the actual rate of discharge of the device, I'm only a user that took some time in share his personal experience in the last 4 and a half months with the device.
1. It was a way of talking, did not tried to assume anything because was not thinking in anithing out of the people that are not having more that 3 hours batt time, was a simple way of selling something (a well/bad introduction depending on the eyes or mentality of the reader)
2. We are at XDA and this is a developer device, I asume a minimal technological base, I was assuming this. But I point this out because I also think that will help some people.
3. Tried to emphasize that while the over sold as an ultra-quick device is only 1Ghz Dual-Core, the GNex can be as fast and reliable as the iPhone 4S with the same speed, and also saving batt (and in addition you have 450 more Megaherzs if you want to use them.. if you root). It’s not condescending cause if I would have liked to buy an iPhone I would bought one as the 99% of the people here.
I am a simple user, as everyone here, trying to help people as people has helped me developing great ROMs and Kernels I like positive and concrete recommendations over vague and negative ones.
hey op,
SrTapir said:
If we take in account that the Mega-Ultra-Cool-Fashion-Posh and "Ultra Quick" iPhone 4S has a only Dual Core 1Ghz processor, we can assume that with the same speed we can achieved a very good optimized and well balanced performance-battery friendly system.. and yes, with the last advances in kernels and ROMs, we can have a perfectly smooth system with a top speed of 1000Mhz.
Click to expand...
Click to collapse
i think the iphone is clocked at 800mhz even it has 1ghz
king23adrianc said:
hey op,
i think the iphone is clocked at 800mhz even it has 1ghz
Click to expand...
Click to collapse
Ups!
SrTapir said:
Ups!
Click to expand...
Click to collapse
First of all thanks to all the people for your comments!
I've updated the first post with your recommendations, and added a couple little things.
SrTapir said:
First of all thanks to all the people for your comments!
I've updated the first post with your recommendations, and added a couple little things.
Click to expand...
Click to collapse
The Calibration section is a little confusing. It only takes 1 hour to go from 0% to 100%?
Also, do you know anything about calibration with ROMs that only allow you to charge to 99%?
myrdog said:
The Calibration section is a little confusing. It only takes 1 hour to go from 0% to 100%?
Also, do you know anything about calibration with ROMs that only allow you to charge to 99%?
Click to expand...
Click to collapse
No, it takes 1 hour after the GNex indicates is fully charged. I'll try to change it in order to clarify.
No, sorry, maybe you can "delete battery logs" via recovery. (I never did it, and don't know if can be detrimental).
Hello ,
That's my first days impression about Xperia S !
any advice plz about improving the battery life please ?
Give it a weeks worth of charges to get going.
although screen brightness and 3G have the biggest impact on battery life
MrBelter said:
Give it a weeks worth of charges to get going.
although screen brightness and 3G have the biggest impact on battery life
Click to expand...
Click to collapse
Thanks for your response , I will give it other chance and see what will happen
By the way screen brightness is nearly 40% and 3g is off
with every thing is off the battery may survive , but hello SONY GUYS , I didn't buy the phone to disable all it's abilities !
Blackjackxx said:
Thanks for your response , I will give it other chance and see what will happen
By the way screen brightness is nearly 40% and 3g is off
with every thing is off the battery may survive , but hello SONY GUYS , I didn't buy the phone to disable all it's abilities !
Click to expand...
Click to collapse
You might consider to check out some other threads before complaining about the battery life. There's many available so browse a bit i suggest.
Tips, Tweaks, and many other good information available on battery life extension. Search, you will find those.
And definitely the battery back up should increase after at least 7-10 days of use.
had the same impression when i first got my sxs, but after about a week or two, and a few tweaks it's pretty good now (1 1/2 day with normal use)
for the screen keep it between 40-60% brightness, especially if indoors. i only set it up to 100% when im outside at long periods of time,
switch off 3G/mobile data when you're not using it, and switch off "account sync" if you're not waiting for some important email etc. 3g/mobile data + account sync will kill your battery really really fast, so i advice refreshing apps manually.
i did some research and its fine to keep nfc open, since it uses very minimal battery WHEN it needs to use the battery which is pretty rare (unless you pass around a lot of data via nfc the whole day, which is pretty unlikely).
if you want to go the extra mile, unlock your bootloader, root your phone and mix and match with different custom roms / kernels that optimize battery life.
A very useful trick is to use 2g when you don't need 3g, it saves one hell of energy..
No idea what you're talking about. My battery goes for almost two days with 3G on all the time.
just use it for two weeks with normal charging. and if i were you, i wont unlock it until two weeks (but i have unlocked mine the first day i bought it..hahaha..),
why do i say this, so that if there are problems occur within those weeks, you can return it without problem.
and you will have more time reading and understanding anything that can be done with your phone,
see my signature "Read ME" for head start.
It's because you've just got it. Is it even updated to the latest software? And you've probably been dicking about with it non stop so of course you'll hammer the battery
Sent from my Jellybean Xperia S
Disable Auto Sync, apps like skype / viber are also hard on battery.
You may also try "Deep Sleep Battery Saver Pro" app.
Thanks for you all , I will try every advice written here
thanks again
Hello Champs.. I am first time user to this forum so pls excuse any idiot questions if it may seem.
I tried to go through threads to find answers but got completely confused, so though to put my question in simple words here.
I have Desire HD running task killer and Juice defender ultimate with extreme power saving option set and also optimized settings but still my phone don't last more than a day of normal usage. I just check emails, read news and call.. I do not play games and use any CPU intensive app. Phone is not rooted and running 2.3.5v of android
One of my friends told me after flashing ROM, battery power is improved by 40% in case of his tablet, so I am wondering if there is any suggestion for me to use for my Desire HD mobile. I have tried all options at application and settings level to improve the battery life.
As I am not too techincal in this field, if someone could write me few high level steps from start to end to get better battery life ROM and / or jellybean on Desire HD, I'll try to find out low level details of those steps in this forum and root (and flash) my mobile.
My sole requirement is to get as much battery as possible and if possible, some latest android version (4.1 or 4.2) to avail the new features.
Also, would there be an option to take the snapshot of current mobile setup in case if rooting / flashing goes wrong, I could revert back to the current version without loosing settings / data.
Thanks for your help.
two things, go to settings>about phone> battery
Or something like that. Take screenshots of your battery consumption, and the amount of time for each. Without that we can't know what's really causing your battery drain.
That said, a day of use will pretty much wind down your phone, the DHD has a very poor battery, decent sized screen, and most modern smartphones don't last terribly long anyways. However, you said you weren't using it too hard, so I'm not sure what it could be
As for juice defender, make sure that the intervals are set to no less than 15 minutes. 10 minutes pushing it. if you set it to 5 minutes, your phone will constantly be waking up from sleep (ultra battery saving mode), and constantly enabling and re-enabling radio. That'll cause more drain than it will save. At 15 you'll notice definitive increases, and at greater your battery will only get better.
Get rid of the task killer, or disable autotask killer and keep task killing to an absolute minimum. Never kill all your user apps at once. Kill only very large resource hogs (e.g. after playing a game, kill it). An autotask killer is very bad for your phone, and for your battery. Linux naturally tries to keep as many processes 'running' or cached in the background, using up a lot of your ram- it makes multitasking better, so in linux this is a good thing. With windows, it does the opposite, and if you run out of RAM you're screwed. A task killer will try to ruin that behavior, and in the end both performance and battery life will suck. It hurts battery life because after you kill that app, it'll just restart itself in the background- using more CPU therefore battery. Plus it also wakes your phone up from sleep when it needs it. I would only recommend a task killer for a phone with 512mb of RAM.
If it's an older battery, you could also have lost a lot of it's charge. I recommend installing battery monitor widget, and letting it run in the background. It'll estimate your mAH (battery capacity). If it's over 1,000, you're fine. If it's around 800, not bad, still doable. If it's at around 600, I would recommend going in for a replacement battery. I'm using an Anker 1500 (amazon), and I highly recommend it. Mugen 1600 is very good one, but it'll cost you a lot more money. I would not recommend an original HTC one.
finally, installing a custom ROM may or may not help battery life. With HTC Sense based ROMs, I've noticed a battery increase. In AOSP (unmodded, as google intended) gingerbread ROMs, you'll also notice a battery increase. With AOSP ICS, JB4.1.2 and 4.2.1 battery life is hit and miss, some ROMs will get you better battery, some will get you worse. You'll need to experiment around with it.
Also, yes you can backup everything after you install a custom recovery. I recommend looking up AAHK (advanced ace hack kit) on google and youtube, as well as rooting and S-OFF in general on youtube.
Thanks for your reply... Really appreciated. I'll look at the suggestions and see if it is unnecessary to root if 1 day battery is expected.
Do you think recommended high power battery actually improves usage time or people just compare their used up battery with new high capacity ones and think they hv got more juice in it. If high capacity ones really give another 2-3 hours of browsing as compared to OEM 1230 mah battery, I would rather buy it instead of flashing Rom.
Sent from my HTC Desire HD A9191 using xda app-developers app