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Old 12-09-2019, 09:36 PM   #1
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Why do Android phones use hundreds of times less power than an SBC?

I have noticed since the beginning how bad SBC computers are with power usage. They are are, to the very last one, hugely inefficient devices.

The reason I ask this today is because I had an incident with my last custom mobile device and am thinking of building a new one.

One of the lowest power SBC computers, the Raspberry Pi Zero uses over 100mA at idle with nothing connected. It seems low, but this is actually garbage power consumption. It is far too weak to browse the modern internet, but it would drain the largest phone battery in just a few hours! That in my eyes makes it one of the worst computers imaginable.

Let's get this out of the way: my Android phone uses 3mA at idle. 3mA x 4.2v = 12.6mV. This is while it is running and listening actively for texts and calls. It has over 2 weeks of actual battery life with a 2500 mah battery. Theoretically it has over a month of battery life.

Let's speculate on why this is:

Is Linux the problem? Android phones run a Linux kernel so this seems unlikely.

Is the SBC market the problem? People have incredibly low expectations of these devices afterall when they think the Pi Zero for example is "low power".

Is the price the problem? I can't find an efficient SBC for ANY price.

Is the processor design scale the problem? I believe the Lattepanda I am using now has a 16nm CPU but still sucks down 500mA at 4.2v.

Are "Sleep states" the problem? This seems unlikely because the Lattepanda I am using uses tens of times more power than my Android phone even when the Lattepanda is shut down!

Are built in peripherals the problem? Unlikely because the Pi Zero has almost none but uses more power than a remote control car.

Is a secretive "hardware cabal" that sets out to make any custom battery powered device impossible the problem? This I can believe in because of how difficult it is to save power. The manufacturers of smartphones have razor thin margins already. If it was viable to build your own they would all go out of business tomorrow.

In Conclusion:
You can see I am in no hurry to build another custom mobile device when SBC manufacturers are not helping me out in the least. Any "new" SBC is just going to be another phoned-in, useless, power draining beast of a board. You would think as long as I have been working on this problem I would have a solution but the power draw is still a mystery to me.
Old 12-09-2019, 11:23 PM   #2
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A phone isn't a SBC now is it?
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Old 12-10-2019, 02:41 AM   #3
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Originally Posted by Jason_25 View Post
my Android phone uses 3mA at idle. 3mA x 4.2v = 12.6mV
Typo? 12.6mVA, or 12.6mw.

But the answer which comes immediately to mind is: All that low power silicon technology comes at a cost/volume which the SBC market won't support. You get what you pay for, proportionally. What did that Pi cost compared to the Andriod phone?

As already noted, the Pi or any SBC is not a phone, and the SBC market is not the phone market.
Old 12-10-2019, 07:19 AM   #4
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3 mils? That's insane!

Here I am trying to get our component section below 100 uA operational and less than 1 for hibernate! (it's not a phone, don't worry about it, true example, but entirely not applicable to a full OS example)

My point there is that it is all in perspective.

Yes a lot of it is sleep states, along with what the CPU is doing. That product I speak of above, runs at 5 mA if we do not write the main loop properly. If instead we do cause it to sleep when it's not doing anything, it is below 7 uA. If we wake it up just enough to fulfill it's requirements and then put it back to sleep, we average far less than 100 uA and we're happy because we've exceeded our power budget in the negative. But originally when we started and didn't implement sleep state, people measured our power and said, "Hey! You guys are above 5 mils!!!!", "Y-e-a-h! We haven't done that part yet!"

There's no hardware cartel ruling things where if you don't pay, you don't save power. The boards you are playing with are hobby boards.
  1. That Android phone is a collaborative piece of engineering where you have dozens or hundreds of resources working on it, starting with the chip, which is capable of performing to very low power levels. These chips costs millions of dollars to design and manufacture. I've been involved with lesser chip designs and overall to bring a design to a first run of like 50,000 pieces, it cost in excess of 5 million. Samsung or other chip manufacturers who design the chips used in these phones has far more money, far greater experience at designing chips, partnerships with the manufacturers if not owning them already, and while their cost efficiencies are better, they also make multiple millions count of their chips, and thus they do a far better job than a smaller company doing odd lots of 50,000 or 100,000 every once in a while. Apple is no exception, they clearly have infrastructure which is far greater controlled and more efficient where they get rich features at very low power, within their cost, because they've done this a lot.
  2. The firmware on the phone, including the Android OS has been tuned so that it operates and allows the system to sleep or hibernate as much as possible.
  3. I can guarantee that you can download apps which will defeat this and if you were to take a data recorder of the power levels of that phone, they would vary greatly where "screen saver on, sitting on the desk, doing nothing", it may be far below 3 mA, and then running GPS, streaming audio, using the phone, it may be at, or above 3 mA during this time.
  4. The difference is that a general SBC you just buy, it runs Linux or Android, but the OS hasn't been tuned to operate as efficiently as possible and thus it is not saving power as efficiently. I'm sure you can tune a version of Android/Linux to do that, but it will take you some effort, along with adding sensors, etc to fulfill the feature requirements; hence a lot of engineering friends to concentrate on various pieces of the problem to make a whole solution which is rich in product features, well tested, and power efficient.
  5. By the way, you're phone is not going to perform this good over time. The lithium polymer batteries have some number of charge cycles which they support, but this also doesn't mean they'll just not charge anymore, instead it means they'll not charge as well, or fully. First of all, the 2500 mAH battery is not all used. There is a usable range, such as 85 or 90% of the capacity, over time the amount of charge the battery will hold, degrades and it may become a 2000 mAH battery 1-2 years later. After which they manufacturer says, the 400 or 500 charge cycle limit has been reached, we can't guarantee that you'll retain greater than xx% of the original capacity, etc, etc. They're getting better, but these are electrical truths. Ergo why phones kind of stink after 2'ish years for those who use and charge them everyday. Meanwhile, if you have efficient charging circuitry, which doesn't do a full charge every time when not needed, or if you use "not" fast charging, it may last longer, or if you're the type of person who doesn't use their phone for much, shuts it off at night or a lot of the time, and charges it maybe once a week, it'll last far longer at the higher quality.
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Old 12-10-2019, 01:16 PM   #5
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3mA x 4.2v = 12.6mV
Does not answer your question but
3 milliamperes X 4.2 volts is not 12.6 millivolts.

ohms law p=e*i
Voltage X Current = Power usage(Watts)
(.003 amps) X (4.2 volts) = (.0126 watts)

my Android phone uses 3mA at idle
Ampere is a measure of current flow through a conductor. Wattage is a measure of power output.
I am using now has a 16nm CPU but still sucks down 500mA at 4.2v.
.5A X 4.2V = 2.1Watts
Then it is dissipating 2.1 watts of power.

A 3000 mAh(milliamp Hour) battery could power a device drawing 100 mA (milliamp - current flow) for 30 hours

Voltage / resistance = current flow

120volts / 1000ohms = .12amps
12volts / 100ohms = .12amps
Same amount of current flow.

My 2 cents
Old 12-16-2019, 08:59 AM   #6
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The LattePanda is X86 and not ARM. X86 consumes a lot more than any arm device.

Most SBC's use older ARM architectures(A53 - A72 vs A57 - A76), and phone SoC's have 5/7 nm design vs 40/28nm of a RPi3B+/4 for example.
The newest Amlogic SoC's are very power efficient compared to other SBC's. The VIM3 for example (12nm) is the most powerful, while it consumes less than the Raspberry Pi4/3B+.
You can also shut down the big cores, and downclock the small cores what makes it even more power efficient.

The SBC SoC's come a few years behind compared to phone SoC's. Why? Because a lot more money goes into developing phones compared to SBC's.
Next year a lot of new better SoC's for SBC's will come out. Those will be 2x as efficient while more powerful. It's a waiting game.

I also want as powerful and power efficient boards. I use SBC's while on big cycling trips to edit and render my videos. I use solar panels and power banks to power them, so the more power efficient, the better for me.
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