Juice Defender is crap on FroYo. It doesnt work properly anymore.
Anyways, I'm testing a method to recalibrate the battery. So far so good. I'll update my findings in this thread.

Ok, so I bump charge my battery and it's performing better now.
After the bump charge, I did some extreme battery draining activities just to test it out:-
1) downloaded 157MB of data through Wi-Fi for the Let's Golf game (it's currently free from Gameloft, BTW)
2) Played a couple rounds of golf.
3) Updating facebook, crusing round the forums with Tapatalk.
4) Sent a couple of emails
5) Trying out the new ADW launcher themes.
6) Made and answered a couple of calls and SMS (normal day-to-day usage)

Around the 12th hour, I still had 63% left on my battery. A full 24-hours and it was at 42%. This is just amazing. When I first used FroYo, the phone would never lasted that long. I'd say without me 'going to town on WiFi and playing 3D games' the battery should last like 2days or more.

Anyways, here's how you bump charge your battery with battery calibration steps embedded. If you're not rooted and have no way of wiping the battery stats, I suppose you can just ignore the step.

1.) Connect the phone to the charger with the phone powered on, and allow the phone to charge until the notification LED is green, indicating the device is fully charged (use OS Monitor to make sure its at 100%.)
2.) Disconnect the phone from the charger, and power it off.
3.) Reconnect the phone to the charger with the phone powered off, and allow the phone to charge until the notification LED is green.
4.) Disconnect the phone from the charger and power it on and wipe battery stats, then reboot.
5.) Once the phone is powered completely on, power it off again and reconnect it to the charger until the notification LED is green for a minimum of 30-60 minutes.
6.) Disconnect the phone, power it on, and use it.

Here are a couple of things to note on my phone setup. They may or may not affect my battery performance results:-
[*] I have Juicedefender running
[*] I run an undervolted kernel. A somewhat unstable one I might add. I grabbed a nightly build from intersectRaven's file dump before realizing that he hasnt officially released it yet. And I'm kinda lazy to re-flash a stable kernel.

You need to that from the recovery console. Amon-RA has that option. Not sure about the other recovery consoles though.

Anyways, the command to wipe battery stats is :-
rm /data/system/batterystats.bin

So if your recovery ROM doesnt have an option to wipe battery stats, you can boot into recovery and use adb to execute that command. It's not a good idea to do this through a terminal emulator on your phone or do an 'adb shell' thing while your phone is running your current ROM. For one, the system (and other battery indicator widgets) are using that batterystats.bin to display your battery status. They'll start throwing some crazy exceptions if you happen to remove the file while they're running.

(for you observant ones, you might notice that I omitted a couple of lines before that 'rm' command. That's intentional. I dont want anyone to recklessly copy-paste-n-run it and later ruin their phones. If you wanna run rm commands in your system directory, you better know what you're doing.)

Nope, you dont need root to bump charge your battery. If you cant wipe your battery stats, just ignore the step. BTW, I stole this bump charging method from XDA. So all the credits should go to the posters. All I did was trawl around 30+ pages of posts and relay the info to you guys on LYN.

Actually the original instructions came from HTC itself. In other words, it is meant for non-rooted phone too. I'll paste the original message here:-


One thing to note is that the LED will turn green even if the battery is not yet fully charge (at 90%). Therefore, in step one, you'll need to make sure your device is fully charged before pulling out the plug and turning it off in step 2.

yup, only once.

I suppose so since it was engineered by HTC.

This post has been edited by cleave: Jul 22 2010, 09:41 AM

If you get green on Step 3, that means your batt is fine and cannot be bumped charged. The idea of bump charging is that a device in an on state cannot get 100% charged because it is contantly discharging. You then 'bumped' the charge further by charging it when it is off. That said though, from the responses on XDA, it is implied that the step 5 is what makes the difference, leaving it to charge for an extra 30mins in an off state.

I guess if you're satisfied with your battery life, you wont need to use it.

That depends on your setup like how many widgets are you using, do you have live wallpaper on etc. An indication that you may need to bump charge your battery is when all of a sudden you feel that the battery life gets shorter even though you're using your phone normally. Let's say that you normally get 1.5 day, out of the blue it dropped to 0.5 day. Your battery then either needs to be recalibrated or it is physically damaged. A total recalibration would be to discharge the battery totally, partial charge, wipe the battery stats and recharge it to full power. But that would need a root permission or some crazy looking adb commands (at least to those outside the Linux world), so HTC came up with this bump charging method that is more suitable for all users (with or without rooted device).

Anyways, EVO 4G is an awesome phone but with a terrible battery life (as reported by its users). Here's a post detailing how to fix it. There are probably some tips in there that may apply to other HTC sets:-
http://www.cloudave.com/link/fixing-the-ba...-evo-incredible

Another unproven myth is that task killers can improve battery life. This has been debated in countless occasions. Do task killers really help? Or is it just a placebo effect? Does it do more harm than good? Here are some good threads on the issue, read them if you have the time and you decide:-
http://androinica.com/2010/05/07/google-an...-are-pointless/
http://www.google.com/support/forum/p/andr...87bb09cba&hl=en
http://forum.xda-developers.com/showthread.php?t=683176
http://forum.legendroid.com/android-genera...-on-your-phone/

I used task killer on my 1.5 Hero. It did help in releasing memory and maybe prolonging the battery life a bit. But since going to 2.1, I didnt see any difference using a task killer in terms of battery life. In fact, on Eclair, I found that my phone was lagging whenever I have the task killer on. So, I abandoned it. On FroYo, task killer is made more redundant as FroYo's memory management is just fantastic. You'll get twice as much free memory than on Eclair.

I assume you're in Recovery. Did you mount the filesystem?

ummm... yes. you can ls the directory to reconfirm.
Actually the safe way to do it is to mv the file to some other place and later if things get screwed up, you can always un-mv the step. But WTH.

yup. if there .bin file wasnt there and you try to rm it, you'll get an error message. An echo would mean that the command was successful.

BTW when I wrote about how to manually wipe the battery stats, I was doing it hypothetically. I wasnt expecting someone would actually attempt it.

This post has been edited by cleave: Jul 25 2010, 11:17 PM

If you charge it during off state and it straight away go green, it is at full capacity. Anyways, if you want a more detailed report on how your battery is faring, go to the Market and look for 'OS Monitor'. If you go to the 'Misc' tab you'll see some info about the battery. If you see 4000mV and you're around 90% capacity or more. Then the battery is fine, generally speaking.

Here's the good part though, something that can measure whether bump charging will have any effect on your batt. Go to the 'Message' tab and click the 'menu' button on your phone. Choose 'Option' from the pop-up menu and scroll down until you see the 'Message' section. In the 'View Log' option choose 'dmesg'. Tap 'Filter dmesg', check 'Enable Filtering', tap 'Tag Filter' and type 'batt' in the text box. Get out from the 'Options' (press 'back' a couple of times) to the 'Message' tab. You'll now see a more detailed stats of the battery condition, including the rate of it discharging. Apply some common sense here, a Desire/Nexus battery is 1400mA (it's actually more but HTC rounds the figure). So if your condition is at 100% and you see the reading is below 1400mAh (like 1300mAh or something worse), then you'll need to bump charge it and reset the battery stats as it is obviously giving the wrong reading. Some guys on XDA managed to get it up to 1480mAh through bump charging. That mAh is actually an indicator on how much juice your battery has. The more, the better.

I dont overclock my set anymore. The last time I did that the battery got so hot and I got panic (was playing excessive Carrom3D). So now I'm back to the default clock settings. But probably things will change since you brought up this Digimon in psx4droid thing. I'm very much interested in raising my own digital monster to battle evil. We'll see how that will effect my overclocking principles soon.

One thing about SetCPU that I recently came across. There's something weird about the widget. I'm not sure whether it's related to FroYo or otherwise but I'll just share it here nonetheless. I was fiddling around with the widget, pimping my screen as usual. After awhile I thrashed the SetCPU widget because it didnt look that nice on my layout. 5 minutes after that my N1 started to behave erratically. Launcherpro was lagging and I get intermittent screen freezes. Soon the phone was soft-rebooting. After it boots up, my Swype and along with a couple of widgets were missing (although their entries showed up in 'Manage Applications' screen). And then the soft-reboot cycle starts again. I went WTF and got annoyed with this behavior. So I logcat it while it was doing its soft-reboot thing. I discovered that problem was there were multiple failed calls to check the CPU speed, although none of the widgets or processes running on my phone that require such calls. Apparently that thrashed SetCPU widget was still living (as a ghost process?) and making the calls.

To fix it, I booted into recovery and wiped the cache and Dalvik-cache. Things went back to normal after that.

That's probably because you typed 'battery' instead of 'batt' in the tag filter like I asked you too.

You only get those from older kernels. Are you on Eclair by any chance?

It's the far right tab.

It works on Eclair too as it is more to hardware than software. Just that the dmesg batt output on Eclair is raw and a hassle to read, unlike Froyo where it is formatted to display in units (mAh and mV). I guess I'll snoop around my old Hero and see if I can come up with a way to translate those weird numbers to comprehensible figure.

And we can swap batteries too.
While iPhones can only rely on software updates to improve its battery life, Androids have wider options for the task. We can do it through software (e.g undervolting the kernel) or hardware (e.g buying extra battery).

This post has been edited by cleave: Jul 30 2010, 09:27 AM

What kernel are you using for that ROM? is it a .32?
Can you do this through ABD? :-
adb shell
? dmesg | grep -i batt

Please show me the output.

settings? I just let it run the setup thing and never touched it after that.

new ROM as in an upgrade from 2.1 to 2.2?
The battery stats should be automatically wiped when you did the upgrade.

Nope, you shouldnt need to.