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Battery Life - The Good The Bad and The Ugly

Does your phone drop 10% quickly in the morning after a full night of charging?

  • Yes

    Votes: 436 79.3%

  • Nope

    Votes: 74 13.5%

  • Not sure

    Votes: 40 7.3%
  • Total voters
    550
meyerweb said:
2x 1500mAh battery + dock charger for Sprint HTC Evo 4G - eBay (item 260599966395 end time Jul-08-10 07:29:11 PDT)

2 batteries and a charger for $11. If 3 batteries won't get you through the day, then nothing will.
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yeah I just got that in, haven't tried them out yet, and I also got an oem TP2 battery bc i heard they are good. so I gave one of the chinese one's to my brother for his EVO. Reading the box that comes with the external charger is worth $11 in itself. There are more words spelled incorrectly than correctly on it...kind of awesome
 
twospirits said:
Nice find, but 25 business days for delivery, damn. Then again anything coming from that part of the world comes by ship usually so yeah 25 days is about right. But the price makes me wonder how good they are.

TS
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I've used similar, Chinese sourced, almost free* batteries in my old Treo. I think they had slightly less capacity than claimed (they lasted maybe 80-90% as long as the OEM battery), but for the price I don't think you can go wrong.

*They cost $1 each, plus $6 shipping. It's amazing how cheap something is when you just wheel a case of them out the back door of the factory. LOL

On the subject of battery life: Today was my second full day owning my EVO. Yesterday, I discharged until I got the warning at 15%, then charged all night. Today, with a lot of playing, web surfing, app downloading, and such, I got the 15% warning after 14 hours. A lot of that time I was on WiFi, not 3G. OTOH, I was out and about for a couple of hours with WiFi turned on, but no hotspots available.

I've already done the things HTC suggested in the earlier post. There's nothign in there lots of people haven't already pointed out. I haven't installed the overclocker program, or ATK, or anything else geared toward saving battery. (I did just install the overclock program. We'll see if that changes anything tomorrow.) I also drained the battery to less than 10%, which took another 40 minutes after the 15% warning. I'll now recharge all night again.

I think that with 14 hours today, I'll easily get 16 to 18 hours with more normal use, once I stop playing with it all the time. That's good enough for me.
 
I am posting screen shots from SystemPanel to see what everyone thinks about my battery. I admit that the testing conditions were under heavy use, as I use my phone as my internet for my laptop (the mobile hotspot feature). The battery started on a full charge at about 9am, and at 3pm, it was telling me to recharge. That's 6 hours of very useful EVO :) But I don't want to stop at 6 hours! I feel like everyone is getting better battery time than that, so I would like input, whatever anyone thinks. I am thinking of doing a hard reset, adding ATK. I had ATK before, and then I uninstalled it because I read the forum lol. I changed the GSM to CDMA with the *#*#4636#*#* thing, but whenever I go back into those setting and click "turn off radio" (I read that in one of the forums as well) then it shows the GSM setting again. Like I said, any feedback would be great. Thanks again!!

-Brittany
 

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Here's my 2nd report:

a. phone on time since reboot: 1:03
b. phone awake time: 0:08
c. battery % 90
d. 4g off, wifi off, BT off, 3g on, 2g on. Background data and auto sync enabled. Android system at 70%

This location has weak signal but signal nevertheless. However the battery usage is identicial to my previous test. may be battery discharge and capacty is not linear so instead of 100 to 90% we should try 90% to 80%?
 
I noticed tonight while charging with SystemPanel open and live monitoring on that the battery % increased from 90-100% while the mV reading only increased by 1mV, from 4201 to 4202. After rebooting I had a reading of 4213 (still plugged in) which jumped down to 4202 again after a couple minutes. Reboot -> 4114 which then jumped up to 4211.

Unplugged #1
- Immediately upon unplugging the charge drops ~100mV and 1%. I plug it back in and recharge to 4202mV again.

Unplugged #2
- unplug - immediate drop of 53mV (4149) but stays at 100%
- 4m - 99% - 26mV (4123) - 4m
- 8m - 98% - 11mV (4112) - 4m
- 10m - 97% - 14mV (4098) - 2m
- 13m - 96% - 0mV (4098) - 3m
- 14m - 95% - 7mV (4091) - 1m
- 19m - 94% - 6mV (4085) - 5m
- 24m - 93% - 9mV (4076) - 5m
- 29m - 92% - 7mV (4069) - 5m
- 38m - 91% - 10mV (4059) - 9m
- 42m - 90% - (-1mV) (4060) - 4m
- 53m - 89% - 5mV (4055) - 11m

This makes me curious as to how the battery % level is even being calculated.

I intend on running the battery dead and noting the readings at less frequent intervals and total uptime. Nearly everyone has experienced the rapid 100-90% drop and most agree that it seems to level off after that. I'm curious whether the delta between the two percentages narrows over time. It would also be great if others would repeat the experiment.

- 1:53 - 85% - 25mV (4030) - 60m
- 5:13 - 79% - 64mV (3966) - 200m
- 8:56 - 75% - 27mV (3939) - 223m
 
vlkswagn said:
I am posting screen shots from SystemPanel to see what everyone thinks about my battery. I admit that the testing conditions were under heavy use, as I use my phone as my internet for my laptop (the mobile hotspot feature). The battery started on a full charge at about 9am, and at 3pm, it was telling me to recharge. That's 6 hours of very useful EVO :) But I don't want to stop at 6 hours! I feel like everyone is getting better battery time than that, so I would like input, whatever anyone thinks. I am thinking of doing a hard reset, adding ATK. I had ATK before, and then I uninstalled it because I read the forum lol. I changed the GSM to CDMA with the *#*#4636#*#* thing, but whenever I go back into those setting and click "turn off radio" (I read that in one of the forums as well) then it shows the GSM setting again. Like I said, any feedback would be great. Thanks again!!

-Brittany
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If you're using it as a mobile hotspot, why not just keep it plugged into the USB port of the laptop while in use? Then you're running off the big laptop battery instead of the itty bitty phone battery.

I think 6 hours of solid radio use is pretty astounding, to be honest.

lettcco said:
This location has weak signal but signal nevertheless. However the battery usage is identicial to my previous test. may be battery discharge and capacty is not linear so instead of 100 to 90% we should try 90% to 80%?
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I'm not sure either 90% or 80% is all that meaningful, unless and until we understand how linear the gauge is (or isn't). The only meaningful tests are going to be to charge it to full, use it all day, and see when you run out of battery, or how much battery is left at the end of the day.
 
The first 10% always disappears quickly, this I concur with.

Try the HTC battery trick (charge on to green, turn off, keep charging from orange to green, boot up, if not booting green, let charge from orange to green, and repeat until it boots up green).

YOU MUST KEEP THE CHARGE CABLE PLUGGED IN FYI!!

Also let the battery drain to 0% a few times, and when I mean 0% I mean let it die (~5%) then try to boot it a few times until it doesn't even power on. :)
 
1. Voltage does not drop linearly w/ capacity. But by discharging the battery a bunch of times (like you did) into a fixed load, you can plot a curve relating voltage and capacity (assuming constant temperature, discharge rate, etc). Most phones are using a model to estimate % remaining, based on voltage and perhaps power-on time and current draw (if they have a sensor for that). It's just an estimate; there's really no way to accurately measure where the electrons are inside the battery :-)

When the battery is new or old, the model will be less accurate.

2. Discharging li-ion/lipo batteries below 20-25% will seriously reduce their life. My guess is that 0% is really around 20-25%, which the SW won't let you use, to avoid damage.
 
rphlx said:
1. Voltage does not drop linearly w/ capacity. But by discharging the battery a bunch of times (like you did) into a fixed load, you can plot a curve relating voltage and capacity (assuming constant temperature, discharge rate, etc). Most phones are using a model to estimate % remaining, based on voltage and perhaps power-on time and current draw (if they have a sensor for that). It's just an estimate; there's really no way to accurately measure where the electrons are inside the battery :-)

When the battery is new or old, the model will be less accurate.

2. Discharging li-ion/lipo batteries below 20-25% will seriously reduce their life. My guess is that 0% is really around 20-25%, which the SW won't let you use, to avoid damage.
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That's what I found interesting. I'm wondering at this point if the rapid decline in voltage output when unplugging from a full charge is one of the reasons we're seeing the rapid decline in calculated battery remaining.
 
Wanted to put up my battery times. I went to an amusement park yesterday. Took it off charger at 11am(give or take few min), and at 8pm I had 50% batt left.

usage:

I texted a lot, talked about 20 min, took about 50 pics, 13, 40 sec vids, surfed the internet a little, uploaded to face book about 4 times, and tweeted and checked tweets like 9 times.

Tweeks:

Not much just normal things like screen brightness was between 80% and 40% (mostly 40%), depending on sun. Checked to see what was running after use, and stopped google talk(don't know how it started). No tweet or facebook widgets, and no live wallpaper. I do have the weather though. Bluetooth off and on, 4g was off. Had a good signal.


I do want to note, when i got to the car i started navigation and my batt went from 50%-30% in like 1/2 hour-45min. I already know gps sucks the hell out your battery and most of the time i plug it in when i use it. I still think these are pretty good times.
 
So in simple terms, are you saying the phone is overcompensating for that initial drop in voltage and showing a lower percentage number initially? Then compensates once again by flattening out the curve?
 
edlex said:
So in simple terms, are you saying the phone is overcompensating for that initial drop in voltage and showing a lower percentage number initially? Then compensates once again by flattening out the curve?
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No. It looks like the phone is relying on the voltage output in calculating the remaining charge. The rapid initial decline in voltage output of the battery is reflected in a quick initial decline in the battery meter. It isn't compensating for the phenomena at all.
 
From your empirical data in your first post, with full charge being 4200mv and 90% being 4060mv, it would imply that 0% would be 2800mv. But looking at your data for 75% at 3939mv it would imply that 0% would be at 3100mv.

So what ever scale HTC/Android is using for remaining battery percentage does not look to be linear and they are doing some compensation.

Typically when charging a li-ion or li-po battery, there is an intial voltage drop when you take it off the charger. Max voltage for a lithium cell is 4.2 volts (4200mv) and minimum is usually limited to around 3.0 Volts to avoid damaging the cell.
 
Just FYI. The 0% point that Android reports from the battery is right when the graph takes that sharp dip toward bottom. 0% doesn't mean 0V. This is to allow the phone to shut down immediately but safely (while using up that last bit of power in the steep drop).
 
dcoaster said:
Just FYI. The 0% point that Android reports from the battery is right when the graph takes that sharp dip toward bottom. 0% doesn't mean 0V. This is to allow the phone to shut down immediately but safely (while using up that last bit of power in the steep drop).
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Who said 0% means 0 volts?

Are you saying that the inflection point is what android uses as 0%?
 
One of the issues that you might be seeing is that once the battery reaches 100% and your LED switches to green from amber, the charging system turns off. Once the battery is down to 95% it turns back on.
 
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