I am a statistician and charted my Epic 4g battery life as a small side project. Here are the results.
METHOD: These are projections from 100% life down to 0% life based upon the drain I got between 90% (when I got to work) to around 30% (when I did not want to risk running out of juice). That is, I calculated the number of minutes per 1% of life then extended that out to a full 100% to 0% drain. I got these projections from writing down the time and the battery % (through the"battery indicator" app).
- Day 1: 12.3 hours. Sync on. GPS on. Fring on (gtalk connected). Juice Defender off (not installed).
- Day 2: 17.2 hours. Sync on. GPS on. Fring on (gtalk connected). Juice defender ON (defaults only).
- Day 3: 18.5 hours. Sync on. GPS OFF (via power widget). Fring gtalk off (I removed the fring gtalk connection). Juice Defender on.
Conclusion: Juice Defender works, but no solution is able to make the Epic 4G last all day with full functionality. A long day is 18 hours. I can get near this (17-18 hours) with Juice Defender. However, to keep the phone at full functionality, one has to stay above 15% (after this, the phone shuts down some services). A long day is 18 hours, so from 100% to 15% = 21.2 hours total.
1) All days were pretty normal: 1-1.5 hours of screen time, 5-10 minutes calling and push mail--no wifi, no 4g, no navigation, fring on, no task killers, latitude installed).
2) I suspect that battery life may be slightly better after the first week (this test was done during the second week).
3) My phone charges at 30% per hour. I try to charge it when it hits 30% and 1 hour gets it to 60%. Another gets it to 90%.
4) The worst thing I ever did to my battery (not on one of these days) was sending a 1.5 meg attachment when I had a half a bar of signal. It took 10 minutes and 10%ish of my battery life.
Another update if anyone is still interested:
I installed Juice Defender Friday night and let it run, accepting all default settings.
Yesterday at 8:00AM I took the phone off charger and now, 30 hours later, the phone is showing 32% battery. Not bad at all. And this is on a battery that has only been charged 3 times.
Here's the breakdown:
Voice calls, 42%
Cell Standby, 22%, time w/o signal 11%
Phone idle 15%,
Android System, 2%
This was light usage, but fairly normal for me. About 45 minutes of voice calls, ~10 minutes of 4G internet, ~10 min of wifi, a few texts and a few edits to my contacts.
I bought an extra battery so I could make it through a weekend of backpacking. It looks like I'll have no problem and may not even need the second battery.
My wife's phone the last couple days is the same as "beam me up". 38 hours since unplugged and 31% left. Same type of usage and numbers.
Can you please tell me where can I find task manager and advanced task killer. I turned off the same things you did so I can prolong my battery life. Thanks!
The Epic comes with a task manager - long press on the Home key, choose Task manager.
Otherwise the apps listed are found in the Marketplace.
So, I've been critical of this phone and customer support because of my battery issues. My first battery was definitely bad. My second battery started off bad but after a few charge cycles, about 5 days, it is working great. I get over 12 hours of use which is what I really need. Using Juice Defender and Advanced Task Manager also seems to help. I've read elsewhere that you need to "break in" this battery. Customer Support should have been equiped with this knowledge but since most people count on that 30 day guarantee, within 30 days most people that have the same issue as me will be satisfied with the product. It's a great phone.
I can confirm what some of you are seeing. I've had my phone for about a week now. I started using it with alot of the functionality on (facebook, accuweather, gmail, & gtalk syncing; GPS & 3G enabled; live wallpaper; etc) and I was barely getting 8 hours off of a full charge. The phone was taking forever to charge as well. I turned off most of the syncing items, and killed most of the background services with ATK and was able to extend it another 2 hours at most. I went to pick up one of the EPIC Charging stations (wall charger, battery, & external charger) last night from Sprint. I easily get 16 hours out of the same config on the new battery. I've marked the batteries so I can continue to monitor them over the next week. I've also noticed that the built in battery meter completely sucks. I run Battery Indicator Pro which is much more accurate it appears. It breaks down time left based on Light, Normal, Heavy, & Constant usage and is fairly accurate at computing this. While the built in battery monitor shows 70% battery, BIP shows it at 47%.
One thing I noticed about charging was the USB cable and charger made a big difference in the charge time. For example, I have a generic USB cable with a really small diameter cable and a .700 A car charger that would maintain the charge (no drain) but not increase the battery charge at all. Changing the USB cable itself to a heavier duty one, and I can see it charge. The cable definately makes a difference. Also, powering the phone off while charging GREATLY reduces the charge time of the internal battery if you don't have an external battery charger. I was able to charge the battery in less than 2 hours that way. The EPIC has a nice feature that shows you the charge of the battery on the screen even though the phone is powered off.
I'm definately believing that some of the batteries we are seeing are not created equal.
Here are the specifics on the two batteries
Original Battery MFG date 2010.08.17
New Battery MFG date 2010.07.30
Yesterday I fired up the WiFi on the Epic, unplugged it at 0700 and used it throughout the day. A few calls, email, lots of background data.
At 0000 hours - all day(!) I still had 20% battery left. 17 hours on a single charge, with WiFi running the whole time.
I am doing something VERY wrong!! My battery dropped 11% in 30 minutes!!! I have Bluetooth on, background data on, Battery Time Lite installed on defaults, and the first wallpaper scene (looks like starts swirling and a tent with a light on).
Battery Use screen:
Cell Standby 7%
Android System 3%
Phone Idle 3%
This is my 1st smartphone and I was wondering why would you even need to use the wifi if you have unlimited data? The wifi uses up a lot of battery life so I don't use it.
Download and Upload speeds will be wayyyyyyyyyyy faster on Wifi than either 3G or 4G connections
I use my EPIC at home conenct to my WIFI and it is just like a very smal laptop