Wonder if anybody has a similar problem.
I use my XDA for work, guessing a lot of people do that, doh! And I work in a warehouse/ outside in UK.
Anyway here goes. By cold temperatures, I mean British weather! Which is in the positive Celcius range, so not that cold..
Last night it happened again. I was out in a field near Hull, working! I made a phone call, then the battery light goes red, 10% battery. In a field how do I charge it!! Simple, stick it in my pocket to warm it up. Within minutes the XDA has 60% again!!
Please any tips or similar experiences. I know that the summer is coming so things look up. But what happens when Autumn comes around again, well my contract is up, so a new phone I do believe!!!! And the XDA will just be a pocket PC, to keep in doors in the warmth.... Maybe a sony...
Martin
Cold and batteries
From: http://www.argreenhouse.com/papers/tony2/ECS00_Bond_Untr.pdf:
Tests of low-temperature discharge rate capability of various commercial Li-ion batteries showed that on average only ca. 30 % of battery capacity can be obtained at a C/2 rate at a temperature of -20 Celsius, and less than 10 % at 1C. Batteries described in this work exhibited higher capacity at C/2 at -20 Celsius (Fig. 10) than most of the recent commercially available Li-ion batteries tested. The discharge rate capability of these samples was a strong function of temperature; at a 2C rate, the capacity utilization decreased from ca. 90 % at 21 Celsius to 24 % at 0 Celsius and less than 2 % at -20 Celsius. In the above example, the C/2 capacity was 99, 95 and 37 % at 21, 0 and -20 Celsius, respectively.
Click to expand...
Click to collapse
(A discharge rate of 1C means "as many Amps as there are AmpHrs in the battery, i.e. theoretically discharging the battery in exactly one hour.)
Polar equipment often has separate battery holders: device out in the open where fingers can touch it, batteries inside insulated clothing with warm human. Tummy or inside of upper leg are warmest...
Thank you
That answers the question then.
Their developing better batteries....
Anybody else have similar experiences though...
Martin
Get yourself a battery pack - runs off 4 AA's. (Search ebay under xda). Absolutely invaluable for traveling.
Regards
Tim
So this is a development idea...
I thought about this the other day and realized that under volting could be causing my battery to die quickly...
Here's why.
V = I * R
Where v = volts, I = amps, R = ohms.
P = V * I
Where P = (power)watts
I know some of you are going to think that this doesn't belong in development, but here me out here.
So if the processor uses 1.5 Watts and we decrease the voltage, this means that the processor needs to increase current to maintain that power. This equates to reduced battery life.
I'm just suggesting that undervolting may be causing the low battery life. If you know better feel free to tell me I'm wrong, but please explain the mechanics of what is going on not just your theory.
This question is over my head so I'll refrain from speculating directly on your theory. But real-world results with my undervolted Stupidfast 1.54 kernel gives me much better battery life than stock. Yes, this may be due also to the unbloated-ness as well so I'm not 100% certain the undervolting is the main help here
Well....I dunno how this applies to CPUs but.... I used to be a car audio installer/buff and when we noticed voltage sagging to an amplifier, the amplifier would compensate by pulling more amperage at the lower voltage. It never seemed to make much different to the batteries, but it did make the amps run much hotter...so....
Again, not sure if it would tie in, but....
Hmm I've never thought about that. From my RC knowledge the most efficient set ups are the ones that use high voltage but low amps.
I may have to try a OV kernel and see if I notice a difference...
Sent from my Samsung Fascinate running BH3.0, DL09, 125mv undervolt Voodoo5 using SwiftKey and Tapatalk
As a disclaimer, I have not performed any formal reading on this topic, these are just my idle ramblings.
My contention has been that you only enjoy the benefits of a UV kernel if you are a certain type of user.
If you are performing CPU intensive tasks, you reap the most benefit from the UV kernel because it needs less power to run at 1 GHz (or whatever the maximum clock speed is set to for that kernel).
If you spend alot of time idling, for instance reading interspersed by web requests, you are spending most of your time at the minimum clock speed. With the stock kernel, that is set to 0.1 GHz. With a UV kernel, the minimum clock needs to be set to something higher to keep the CPU running. You may be able to estimate what this speed needs to be based on the fundamental power calculations in the OP.
The governor quickly changes your clock speed based on your current usage & requirements. To make optimal use of the CPU governor, it should have access to the broadest possible range of speeds (without going higher than is useful/safe). Unfortunately, undervolting a kernel sacrifices some of the lower end of that range. Therefore, many users see much improved battery life, while others (like me) experience noticeably diminished overall performance from UV kernels.
Swyped w/ XDA App. When in doubt, mumble.
P=V*I
The processor does not draw a constant power, but it does have a minimum. The point of undervolting is bringing the power consumption to that minimum within the phones physical environment and user expectations of functionality.
So...
You are right.
However, processor frequency is dependant on current. Thus if you are undervolting to save battery life then you will need to keep your frequency the same or lower to notice a difference. If you are overclocking (increasing current) and undervolting then your P stays the same so the user ends up feeling the battery life to be the same or worse.
Facundo
Are there any standard or over volt kernels available so we can test this theory? It seems as though all the kernels available are UV.
Sent from my SCH-I500 using XDA App
would you like a standard voltage kernel to test?
Personally I see worse battery life on UV kernel. My usage mostly equals to dumb phone, with email sync and moderate web browsing.
I would change formula to I = V/R, which will read as current is directly proportional to voltage and inversely proportional to resistance. That makes obvious that reducing voltage we decrease current. However one point to note here is that this law is for PASSIVE conductor, which is obviously not our case. I would not speculate further, because we do not know what king of power conversion happens. It might simply turn out that conversion is not efficient at lower voltages. Google desktop power block certifications/efficiency to see whet I mean.
I compiled some kernels so you folks can play with it. I SERIOUSLY doubt you will get better life with my stock voltage vs. undervolt, but give her a shot.
Undervolted
Voodoo
http://adrynalyne.us/files/kernels/adryn_test2_0116_fascinate_voodoo5.zip
Nonvoodoo
http://adrynalyne.us/files/kernels/adryn_test2_0116_fascinate_novoodooo.zip
Standard voltage
Voodoo
http://adrynalyne.us/files/kernels/adryn_sv_0116_fascinate_voodoo5.zip
Nonvoodoo
http://adrynalyne.us/files/kernels/adryn_sv_0116_fascinate_novoodoo.zip
I'm giving the SV Voodoo kernel a try right now.
Sent from my Samsung Fascinate running BH3.0, DL09, and Voodoo5 using SwiftKey and Tapatalk
I thought about this as I thought about power lines. They use super high voltages to reduce the amount of power loss through the lines.
Anyways, sounds good, I'll test it out. I'd have to get a baseline. I guess I'll charge my phone right now and test out the regular voltage.
I'll let you guys know tomorrow the differences tomorrow.
In all honesty, I don't ever feel that I get more juice out of unvervolt kernels and I've been using all kinds of kernels since the release of MT3G.
Thanks for the standard voltage kernel!
I do appreciate you efforts in continually optimizing these, having a baseline to compare to just makes it all the more wonderful.
I will give the SV (standard voltage) a day or so of testing and then compare the UV against to make the test fair. With ten minutes of use ^^, it is already a great contender for my daily driver. I had gone back to 11/29 from 12/30. 11/29 was a terrible pairing with DL09; my GPS was unusable.
$ busybox md5sum ad*.zip
aea1047f3b2d33e759064d47cc8cac27 adryn_sv_0116_fascinate_novoodoo.zip
Works great!
Swyped w/ XDA App. When in doubt, mumble.
I wonder if android has battery test application, just to be put everything in the same play field? It's kind of pointless to compare subjectively.
Well, I tried to be objective with this test I just did.
Here were my conditions:
Charge to full, write down the time it was at full charge which wasn't 100%.
Let it sit for one hour.
Write down the charge.
SV Conditions
Starting charge 99%
Ending charge 97%
UV Conditions
Starting charge 98%
Ending charge 96%
The results...
SV - 3% discharge / hour
UV - 2% discharge / hour
Errors analysis:
There are several issues with this test because they were not even at the same charge at the start. Batteries have their maximum charge at 100%, and the rate of decrease is not a linear decrease. More testing is needed to compare the results.
Also the duration is not long and other factors have not been considered such as background applications refreshing on their own. I will have to test for 8-10 hours of each at idling tomorrow to get an accurate measurement.
Currently, I'm still on the UV kernel and I'll publish my results tomorrow of the UV over the 10 hour period.
Then I'll try to not use my phone throughout the day and test the SV.
It would be nice if someone could test the SV and UV with moderate usage and write down the initial charge, final charge, and the duration between the measurements. And another using heavy usage.
Thanks.
RacerXFD said:
SV Conditions
Starting charge 99%
Ending charge 97%
UV Conditions
Starting charge 98%
Ending charge 96%
The results...
SV - 3% discharge / hour
UV - 2% discharge / hour
Click to expand...
Click to collapse
Im confused with your math here...
Yeah, your math is off.....
Sent from my SCH-I500 using XDA App
RacerXFD said:
So this is a development idea...
I thought about this the other day and realized that under volting could be causing my battery to die quickly...
Here's why.
V = I * R
Where v = volts, I = amps, R = ohms.
P = V * I
Where P = (power)watts
I know some of you are going to think that this doesn't belong in development, but here me out here.
So if the processor uses 1.5 Watts and we decrease the voltage, this means that the processor needs to increase current to maintain that power. This equates to reduced battery life.
I'm just suggesting that undervolting may be causing the low battery life. If you know better feel free to tell me I'm wrong, but please explain the mechanics of what is going on not just your theory.
Click to expand...
Click to collapse
I'm an electrical engineer, and none of this makes any sense. V=IR is for current and voltage going through/across a constant resistor. Transistors are not constant resistors. The current through a Metal Oxide Semiconductor Field Effect Transistor (MOSFET), the type of transistor that is in basically all ICs, is always in positive relation to the voltage, at least for the purposes of this basic explanation. Decreasing the supply voltage, which is you can consider to be the VGS of a transistor for a simple analysis, is always going to decrease the current as well. Thus, depending on the range of operation of the MOSFET, decreasing the voltage will also decrease the current and thus power will decrease more than linearly. Less current means that the transistors will charge and discharge capacitances slower, and that's why you need voltages for higher clock speeds and overclocking IN GENERAL. Device physics is really weird.
Now, someone else was saying that maybe because you undervolt it less current goes through which means it needs to spend more time in a higher clock state. This is completely false, the current going through it has nothing to do directly with the amount of work done. Yes, you need more current for faster clock speeds, but at a given clock speed, it doesn't matter how much voltage or current there is and how fast the individual parts of the circuit work, as long as the longest delay in any part of the circuit is less than the clock rate. If it's longer than the clock period, then your circuit is no longer going to function and you'll have instability and crashes, but there is a bit of wiggle room designed into these circuits because each chip can be different. That's why you can overclock or undervolt a CPU, because obviously if it was designed to run at the fastest clock speed possible, any little variation in supply voltage, temperature, manufacturing process/lithography (which is very common) would cause your CPU to completely not function. You have to design your circuits to be tolerant of some amount of error from many sources (even cosmic radiation in some cases), otherwise it won't just be slow, it won't function at all. Logic circuits are clocked to synchronize data going through the circuit, and if the timing constraints aren't always obeyed you'll get wrong answers which would probably crash your OS. Undervolting will never cause the CPU to do less work in one clock cycle, unless you undervolt it too much, in which case things will likely blow up in your face.
Sorry for the wall of text, but hopefully this will clear up some stuff. And in the future, please stick to what you're good at and don't try to speculate things based on one formula that you heard sometime in physics while you were half asleep, or something some CSR told you to get you to shut up. Believe it or not, the people who are designing CPUs and writing/modifying kernels and operating systems actually know what they're doing and you're not going to suddenly realize that they're going about their business wrong because of something you learned in high school.
Edit: One other thing. The calculation of percentages of battery life is a bit of guesswork on the side of your phone, trying to determine via statistics what a voltage level means in terms of percentage of battery life. Battery voltages don't drop linearly as you use them, and can be affected by many things, such as whether it's plugged in to the charger in particular. That's why you see a drop immediately when you unplug your phone, and why looking at 2-3% differences is completely meaningless. The better way to test would be to actually see how long you can use it with an equal amount of work being done on each voltage, which is hard to do in real life. Too many variables are present in today's smartphones, what with background tasks and data coming and going and the like. And wireless radios are a huge battery drain, especially when you're receiving a weak signal. I would advise people to just carry a charger or usb cable with them and top up your battery when you need to rather than worry so much about small differences in battery life. You'll save on a lot of stressing .
Thanks for the explanation. I'm an aerospace engineer. I did have to take a few courses in EE, but nothing to your level. So please let me know if I'm completely off on my testing.
I am pretty sure that the Devs know what they're doing, but I was getting tired of my low battery life and I was willing to test this theory of mine out for them. Again, seriously if I am completely out of the park in terms of this testing, let me know. And I'm ok with being called stupid as long as you teach me what I did wrong...
Yea, I completely forgot how with transistors, the math regarding voltage is handled differently than through a resistor. Are you telling me that the battery life will not be different between standard voltages and under voltages?
EDIT: I understand what you're saying about lowering voltage lowers current because the current has a linear relationship with the voltage in a MOSFET chip. Thanks, I had to read that like 5 times to understand and remind myself.
This is a complete waste of my time at this point because I know what's going on, but I wish to share my results anyways...
Ok here's where I got with the testing since last night. I realize that battery life is nonlinear. But i figure this is better than nothing.
But I did complete 8 hour test of SV at idle.
Starting charge percentage 94%
Ending charge percentage 82%
Which results in 1.5%/hour discharge rate at idle.
Will do the undervolt today. I'll document that in roughly 8 hours.
is there an accurate battery monitoring app that works on the motorola atrix for mA amounts while the battery drains? and the reason I ask if there is one that is accurate, because I have tried using currentwidget, its shows no data for mA, but displays % and the mV. I am in the process of trying battery monitor widget now, but after going on almost to the end of 2 days, I don't believe it's actually accurate. While my phone is not being used and screen off it's lowest standby reading was draining between 15-22mA, losing about 1% of battery every 30mins or so according to the history readout.
im running cm7 beta, faux .2.0 1.3 kernel, radio n_01.77.30p, it's an unlocked motorola atrix from bell that im using on rogers. tegrapart d00
Nothing will give you an "accurate" mA reading unless you can tell the actual mAh capacity of YOUR battery rather than what the battery is rated at. Any app that reports mA is going to be calculating it according to the mAh you say the battery is (again, already inaccurate) and how quickly the battery level percentage is dropping. There is no mA reading that it can just report, its just guessing from given data.
For Battery Monitor Widget though, 15-22mA on standby is weird, I've used that app for months and it has always said 5mA discharge for standby situations. Did you tell the app your battery's mAh rating or is it still whatever the default value is?
its still default i guess, i went to calibration tab, the total max and min are empty
the other fields below say
max: 4205mV min: 3164mV
stored: 1880maH total: 1880maH
measured: pro version only...(that one is obvious...lol)
Your battery should be rated 1930maH unless you are using a non stock battery.
Wirmpolter said:
its still default i guess, i went to calibration tab, the total max and min are empty
the other fields below say
max: 4205mV min: 3164mV
stored: 1880maH total: 1880maH
measured: pro version only...(that one is obvious...lol)
Click to expand...
Click to collapse
mV != mAh
mV measurement used in the BatteryCalibration app doesn't show your battery capacity. It can only be used as a reference point to when your battery is at 100%. (for 100% it should be around 4200mV).
I'm working on a research project about Android smartphones power consumption. Using "adb shell dumpsys batterystats" interesting stats can be obtained. For example:
Statistics since last charge: System starts: 0, currently on battery: false
Time on battery: 1h 0m 38s 51ms (99.7%) realtime, 1h 0m 38s 50ms (99.7%) uptime
Time on battery screen off: 30m 21s 169ms (49.9%) realtime, 30m 21s 169ms (49.9%) uptime
Total run time: 1h 0m 47s 207ms realtime, 1h 0m 47s 207ms uptime
Start clock time: 2016-06-18-22-57-54
Screen on: 30m 16s 882ms (49.9%) 1x, Interactive: 30m 16s 367ms (49.9%)
Screen brightnesses:
dark 10s 89ms (0.6%)
light 30m 6s 793ms (99.4%)
....
Estimated power use (mAh):
Capacity: 6700, Computed drain: 298, actual drain: 335-402
Screen: 244
Unaccounted: 36.9 ( )
Uid u0a90: 15.8 ( cpu=15.8 )
Uid 1000: 9.58 ( cpu=9.49 sensor=0.0868 )
.....
As far as I know, the power_profile.xml is used to estimate the power consumption of each hardware component, and differs from device model to another.
Now I have couple of questions:
Q1: How does Android compute the actual drain ? I looked everywhere and I can't seem to find an answer. I also checked Android code, but unfortunately I couldn't identify the implementation of the method theat is responsible for "actual drain".
Q2: How Android estimates the screen power consumption ? the screen's value when it is on "light = 75%" state is:
ligh: 120.96 ( and it's in mA according to the power_profile.xml), I found this value on Nexus 9.
However, the report says the consumption is 244 mAh for about 30 mins, it doesn't make sense to me ! Can you guys explain it ? I tried to check the source code but again I couldn't find it.
Q3: How accurate these values in the power_profile.xml ? I found here some posts reporting some issues for Samsung devices. But I don't know about Nexus 9.