Why Watts Should Replace mAh as Essential Spec for Mobile Devices (theverge.com) 182
Tech manufacturers continue misleading consumers with impressive-sounding but less useful specs like milliamp-hours and megahertz, while hiding the one measurement that matters most: watts. The Verge argues that the watt provides the clearest picture of a device's true capabilities by showing how much power courses through chips and how quickly batteries drain. With elementary math, consumers could easily calculate battery life by dividing watt-hours by power consumption. The Verge: The Steam Deck gaming handheld is my go-to example of how handy watts can be. With a 15-watt maximum processor wattage and up to 9 watts of overhead for other components, a strenuous game drains its 49Wh battery in roughly two hours flat. My eight-year-old can do that math: 15 plus 9 is 24, and 24 times 2 is 48. You can fit two hour-long 24-watt sessions into 48Wh, and because you have 49Wh, you're almost sure to get it.
With the least strenuous games, I'll sometimes see my Steam Deck draining the battery at a speed of just 6 watts -- which means I can get eight hours of gameplay because 6 watts times 8 hours is 48Wh, with 1Wh remaining in the 49Wh battery. Unlike megahertz, wattage also indicates sustained performance capability, revealing whether a processor can maintain high speeds or will throttle due to thermal constraints. Watts is also already familiar to consumers through light bulbs and power bills, but manufacturers persist with less transparent metrics that make direct comparisons difficult.
With the least strenuous games, I'll sometimes see my Steam Deck draining the battery at a speed of just 6 watts -- which means I can get eight hours of gameplay because 6 watts times 8 hours is 48Wh, with 1Wh remaining in the 49Wh battery. Unlike megahertz, wattage also indicates sustained performance capability, revealing whether a processor can maintain high speeds or will throttle due to thermal constraints. Watts is also already familiar to consumers through light bulbs and power bills, but manufacturers persist with less transparent metrics that make direct comparisons difficult.
I see this with RVs as well... (Score:2)
I've seen this with RVs. However, people get used to stuff like a 12 volt battery bank with 1200 Ah is something that can power an air conditioner for 8-12 hours, depending on the BTUs of the A/C [1]. Switching that to 14400 watt-hours or 14kWh makes sense, but people don't really like that change.
[1]: BTUs, tons (1 ton being 12,000 BTU), etc... IMHO, it would be nice to just do that with watts. Same with horsepower. However, I'd be tarred and feathered saying that someone's 300 hp engine is 223 kW.
Re: (Score:2)
Re: (Score:2)
Re: (Score:2)
Not sure why
Because gram calories sounds stupid, and joules are just begging you to misuse them.
Re: (Score:3)
What the fuck is "BTU"? You still burning coal in your shit hole?
I take it you’ve been stuck in some shithole for the last decade or three, and never heard of a data center before. Or understand how they are specced out and built.
Re: (Score:2)
I lived in the Denver in the late 90s and came across BTUs for the first time on the back of my energy bill (although it wasn't in BTUs) and shopping for window A/C units. I'm from Britain and I'd never heard of British Thermal Units before. WTF! I guess if you're still talking in terms of Fahrenheit and measuring water in lbs then BTUs might marginally make sense. Meanwhile it's all Watts and Watt-Hours here in the UK.
Re: (Score:3)
Now use Watts and Watt-Hours to compare the outputs of a window A/C unit vs a heat pump.
Oh, right, Watts aren't actually a unit of heat and efficiency differences make the two produce wildly different amounts of cooling. A heat pump can produce up to 3x the cooling per Watt compared to a window A/C unit.
We could switch to the SI unit, the Joule, but 1 BTU = 1.055 megajoules. All it would do is confuse people for a few years until they started treating them as the same thing and cost a small fortune rewrit
Re: (Score:2)
I live in the UK, so no need to worry about domestic A/C ;)
Re: (Score:2)
Re: (Score:2)
Heat pumps always specify a COP which you can multiply the power consumption by to get the heat transfer output.
Re: (Score:2)
There are equivalent metric measures for BTUs, but you aren't going to like them.
In fact, I'm going to go out on a limb and say BTUs are still widely used in the UK.
Quick google seems to back that up. [appliancesdirect.co.uk]
Re:I see this with RVs as well... (Score:4, Funny)
Right, we don't use BTUs, we use "tons" of refrigeration! er...
I just replaced my HVAC system. The furnace was in BTUs and the AC was in tons. Honestly, they could be in calories per fortnight so long as I know they are sized properly for my use case.
Re: I see this with RVs as well... (Score:2)
The BTU specs are right next to the mJ. Except most of the time products don't include the Joules rating.
Watts (Power) is USELESS fort CAPACITY (Score:2)
Watts (volts x amps) is great for knowing how much POWER the battery can output (peak watts, constant watts - the size of the gasoline pipeline), but USELESS to know how big of a battery (how much gasoline/fule the tank holds) it is. mAh at the very least lets us calculate the battery capacity by multiplying the battery's voltage spec to get ENERGY (how much gasoline it holds). Ideally we'd know all of the above--ENERGY (in watt-hours, kilowatt-hous), CURRENT capacity (peak and safe max average amperage c
Re: (Score:3)
TFS specifically mentions watt-hours, and we know that's what the author means, so you're just being pedantic. If there's anything to criticize here, it's that when only a mAh spec is given, you can usually assume the device is running on a 3.7v nominal LiPo cell and do the math yourself. More often than not, when you're dealing with a device powered by multiple cells in series, a watt-hour rating will be provided and/or the nominal voltage of the pack will be specified.
The big notable exception that stan
Re:Watts (Power) is USELESS fort CAPACITY (Score:4, Insightful)
Especially because Amp-hours already has hours. We're replacing the amp with watt, not getting rid of the hours.
Re: (Score:3)
The headline may be misleading, but the summary I think is pretty clear, the author is calling for battery capacity to be specified in Watt-Hours, and for power draw in Watts to be a key spec given for devices - the example's right there - he's not calling for battery capacity to be specified in Watts.
Re: (Score:2)
So while you are technically right, and it is worth point out Watts are not a measure energy storage, maybe you are being a bit pedantic in the way you make your point?
Re: (Score:2)
I see SOMEONE read ONLY the FUCKING title.
CAPITALS!
Re: (Score:2)
Re: (Score:2)
Funny
Re: (Score:3)
And yet my 5Ah battery pack stores way more energy than your 12,000mAh one, and can charge a lot more devices.
Mines a drill battery with a USB charging attachment. Ah are just a proxy for energy, i.e. J or Wh, but one dependent on the battery voltage. I think it's better to stick to the units you actually want not proxies with hidden scaling factors.
For example: how long would your expect a 10W charger to charge a 5Ah battery. Now do the same calculation for a 100Wh one.
Re: (Score:2)
other units are just noise - why does it matter to you that its a 6 volt, 12 volt, or 24 volt thingamabob? It matters if your device needs a 6 volt, 12 volt or 24 volt power supply and doesn't work with a different voltage.
It's like an ancient 3 1/2" floppy disk. It doesn't matter how big it is; what matters is that a 3 1/2" floppy disk is a floppy disk that fits into a 3 1/2" floppy disk drive. Or button batteries where the size is printed on the batteries; you don't care about the actual size, you just care that you have the right size that fits your device.
Re: (Score:2)
My vote is simply amp-hours and amps. other units are just noise - why does it matter to you that its a 6 volt, 12 volt, or 24 volt thingamabob?
Because an amp hour at 24 volts is four times more energy than an amp hour at 6 volts.
If your "thingamabob" draws 5 watts, and you have a 10 A-hr battery, how long will it run? Yes, it matters whether it's 6 volts or 24 volts.
Re: (Score:2)
How about electron-volts?
Verge is ignorant (Score:2)
Somehow they thing that giving them watts will magically allow them to estimate battery life completely ignoring non-linear power drain of batteries but are too dumb to do a basic multiplication to get the watts they so truly want.
They trivilise a complex matter while thinking a unit change will fundamentally improve things.
Re: (Score:3)
For the longest time the entire game of The Verge was to pretend they were journalists with expertise, that they were a multi-dimensional version of the specialty rag when they were, in fact, frauds that pushed manufacturer speeds and feeds for profit. Now the veil is off, The Verge proudly displays its ignorance and incompetence. The Verge now wants the public to see who it truly is, a dumb-as-fuck reflection of society as a whole.
Re: (Score:2)
Somehow they thing that giving them watts will magically allow them to estimate battery life completely ignoring non-linear power drain of batteries but are too dumb to do a basic multiplication to get the watts they so truly want.
First of all, even my flashlight has a boost-buck converter that makes power draw constant. Your cell phone certainly has a switching converter. Moreover, you can't convert amp hours to watt hours with basic math. Or any math. There's not enough information. The easy way is to integrate the measure of voltage over time under constant current discharge. I suspect you know this, but in your eagerness to make Verge sound dumb, you misrepresented the physics.
Re: (Score:2)
It's not always obvious nor advertised the voltage they are using to quote you mAh, so calculating the total energy storage capacity isn't always straightforward.
A country that still uses Fahrenheit (Score:2)
Re:A country that still uses Fahrenheit (Score:4, Interesting)
As someone who lives in Florida, I can tell you precisely what is wrong with Celsius: A set point of 23C will run the air conditioning until it is too cold, and 24C will let it get too hot before it kicks on. Whereas a thermostat with a 1 degree swing set at 74F is just heavenly.
I guess folks who are just used to being miserably uncomfortable in their homes all the time don't get it. Certainly, the same thing could be accomplished by adding a decimal of precision to the Celsius mode, but it seems like the thermostat manufacturers haven't caught on.
Re: A country that still uses Fahrenheit (Score:2)
That's not really a problem with units, but with thermostat makers user interface, sadly. My Carrier infinity system thermostats supposedly measure 1/100th of a degree internally (not sure if F or C), in each of the 10 zones, but the screen and hard buttons don't display a decimal point, or allow one to be set, unfortunately. I left my system on F, because I like finer control as you do, though not specifically 23/24C. But even after living 29 years in the USA, it continues to bug me to see temperatures in
Re: (Score:2)
That's not really a problem with units, but with thermostat makers user interface, sadly.
Comparing whole values between the two, the closest the Celsius scale can get is only within 2.2 degrees of accuracy on the Fahrenheit scale.
Yes. That IS a problem of unit conversion. One scale is far more gross than the other. Especially if vendors don’t bother with decimal options.
Re: (Score:2)
Yes. That IS a problem of unit conversion. One scale is far more gross than the other. Especially if vendors donâ(TM)t bother with decimal options.
No, it really isn't. It's the user interface of specific thermostats. I don't recall which countries I was in at the time, but I've definitely seen thermostats in hotel rooms where the up and down buttons change the set point by 0.5 degrees Celsius and the display showed the set point with either a .0 or .5 at the end.
It's a UI decision whether a display shows integers only, one decimal place restricted to only .0 or .5, or one decimal place that can take on all values from .0 to .9. I agree integers only i
Re: (Score:2)
..I agree integers only is more aesthetically pleasing, but who really cares about the aesthetics of a thermostat's LCD.
No one cares. Just as no one cares to be forced to find human comfort within fractions of whole numbers somewhere between 23C and 24C. This is how the more reasonable scale of Fahrenheit was justified.
If a system displays whole numbers in Celsius, then it’s reasonable to assume that system is probably limited to that accuracy until proven otherwise. Are there different accuracy requirements between Celsius and Fahrenheit vendors who sell whole-value only appliances? Yes. Because of the scale dif
Re: (Score:3)
If a system displays whole numbers in Celsius, then itâ(TM)s reasonable to assume that system is probably limited to that accuracy until proven otherwise.
But the system doesn't display whole numbers, that was my point. I have seen with my own eyes and adjusted the temperature with my own finger on thermostats in several hotel rooms where the system displayed and performed in half degrees Celsius.
I'm not disputing that there may also be thermostats that only have a resolution of whole degrees Celsius, but I know for a fact that ones exist that function in half degrees Celsius.
That makes it a user interface issue because thermostat designers make the decision
Re: (Score:2)
Re: (Score:2)
"This is how the more reasonable scale of Fahrenheit was justified."
You literally typed this sentence out and posted it. Home schooled?
No, stupid. I’m a well-seasoned human who’s lived on this planet long enough to know our temperature-driven systems designed for human comfort quite often need more than 2.2 degrees of accuracy.
As justified by many a woman whom the audience here clearly struggles to relate to.
Re: (Score:2)
"I've definitely seen thermostats in hotel rooms where the up and down buttons change the set point by 0.5 degrees Celsius and the display showed the set point with either a .0 or .5 at the end."
Correct. This is the world's dumbest partisan argument. Even SuperKendall isn't this bad.
Re: (Score:2)
"Especially if vendors don’t bother with decimal options."
No, ENTIRELY because vendors don't bother with decimal options (if that is even true). Built into this absurd working-backwards discussion is the implication that these two units of temperature were DEVISED for the purpose of setting a thermostat, one obviously designed better than the other. No one even needs to say how stupid you are for even taking up your side of the argument.
And "decimal options" aren't required either, only fractional o
Re: (Score:2)
For me, I just find that Fahrenheit maps to a nice 0-100 scale for human comfort. 70 in terms of grades is a C, or average grade, and is an "average" comfortable room temperature. Anything below 0 or over 100 is going to require some special preparation to be outdoors comfortably for extended periods. Other types of weather fit nicely into 10 degree increments. 50-60 is sweatshirt weather, 90-100 is great for swimming, etc.
Re: (Score:2)
I don't think any human can appreciate the difference of one deg celsius at that range. You are talking bollocks.
Besides, my thermostat at home allows for 0.5 degrees. It's a google nest.
Re: (Score:3)
I don't think any human can appreciate the difference of one deg celsius at that range.
You have never worked in an office. A single degree F delta is noticed by people who have very strong opinions on appropriate temperature.
Re: (Score:2)
Yes, they notice it immediately either from the dial that sets it, or from the temperature sensor on the AC.
And it doesn't matter that a properly calibrated thermometer will show a completely different temperature at that very moment.
Re: (Score:3)
Besides, my thermostat at home allows for 0.5 degrees. It's a google nest.
I have a few very cheap thermometers from aliexpress. They display 10ths of degree celsius, and two of them show almost exactly the same temperature in the same location.
Re: (Score:2)
I don't think any human can appreciate the difference of one deg celsius at that range. You are talking bollocks.
Besides, my thermostat at home allows for 0.5 degrees. It's a google nest.
Nearly all thermostats that offer centigrade temperatures allow half-degree increments, and that is precisely because your first statement -- that humans can't appreciate or notice a 1C delta -- is completely wrong. Which is why Centigrade isn't great for human temperature use. Fahrenheit is weird, but its granularity is a very good fit for what temperature deltas humans can feel and care about. Its 10-degree increments are also quite meaningful in human terms, and its 0-100 temperatures are a good approxi
Re: (Score:2)
If only someone would invent a number between 23 and 24 for the delicate among us.
Re: (Score:2)
> and those that put men on the moon and brought them back safely.
Using german scientists that were kidnapped during operation paperclip. All of which used metric.
Re: (Score:2)
and also use metric pervasively. Just because Americans use imperial units doesn't mean they use imperial to the exclusion of metric, quite the opposite.
Imperial vs metric is an intelligence test of sorts, but not in the way the stupid people think. In ways where it is important, American industry uses metric, in ways where it is not important they do whatever is expedient. But MAGA douchbags can only see a reductionist opportunity for derision, everything is a tribalist fight to the death.
Wh, not W (Score:5, Insightful)
The capacity of a battery can usefully be specified in Wh. Power draw is in W, multiply by the time that power is drawn to get the capacity you used.
Wh is superior to Ah: if you only know the Ah, you have to find out the voltage of the battery to find out what capacity it has. Power draw for devices is generally specified in W, not A.
Re: (Score:2)
The useful battery capacity that the owner can get is complicated by the fact that these days batteries are rarely used directly, but rather their output voltage is adjusted via a step up or down converter, often more than once. You can see that with USB power banks, where the actual performance you will get depends on what voltage your phone wants, how much current it pulls, the starting and ending SoC etc.
A single number will never give you a good indication of performance, or even allow for fair comparis
Re: (Score:3)
The useful battery capacity that the owner can get is complicated by the fact that these days batteries are rarely used directly, but rather their output voltage is adjusted via a step up or down converter
Which is exactly why capacity should be specified in units of energy: Wh or Joules.
Do you even physics, bro?
Re: (Score:2)
But those don't take into account the inefficiency of the voltage conversion. From a consumer point of view they want to know what to buy, not what the capacity of the internal battery is.
It's even worse when they try to compare it to their phone. Knowing the energy in the phone battery and in the mobile battery doesn't tell them how many actual charges of the phone they can get.
Re: (Score:2)
But those don't take into account the inefficiency of the voltage conversion.
So adjust it for a nominal efficiency rating.
What do you propose instead?
Re: (Score:2)
The usual solution to this is a set of standardized tests, say for common USB PD voltages at the maximum current available.
Re: (Score:3)
The usual solution to this is a set of standardized tests, say for common USB PD voltages at the maximum current available.
That's not an answer to the question, because it talks about measurement, whereas the discussion is about how to specify capacity for the user.
watt hours should've always been the unit.. (Score:2)
Re: (Score:3)
A unit that actually means something (Wh) is objectively superior to the useless unit we're stuck with due to "we've always done it this way" (Ah).
No consumer understands the Ah unit, either.
Re: (Score:2)
No, the problem isn't me. The problem is that a spec is used that is useless on its own and requires calculation (of a type that not everybody is familiar with, and that requires data not everybody has) before it is useful for any purpose at all.
Re: (Score:2)
For that second part the mAh (not Ah, but mAh) is objectively superior to the consumer if product B already has that unit then listing product A in Wh is beyond useless to them.
Unless the two products have different battery voltages, or even just sufficiently-different battery performance curves. Though honestly neither Ah nor Wh are what the consumer really wants to know, which is just h, because different products draw different amounts of power.
The best option, for both engineers and consumers, is for devices with internal batteries to provide hours of battery life for each of a few different usage patterns, along with watts for each usage pattern, and for external batteries
Why we should quote EV battery capacity in Joules (Score:5, Insightful)
Battery manufacturers could have competitions about who will be the first to get a gigajoule into an SUV, and we could quote battery density in Joules per cubic meter
Re: (Score:2)
I'd rather like it if instead of telling me my battery is 85KWh, I could have a 300 MegaJoule battery. Battery manufacturers could have competitions about who will be the first to get a gigajoule into an SUV, and we could quote battery density in Joules per cubic meter .. oh, the beauty of SI units and the metric system.
I was really hoping we would somehow avoid highlighting the asinine stupidity that is car marketing, but let me remind you of JUST how moronic we still are today. There are exactly zero horses under any hood of any car. 99% of the driving population has never ridden a horse, or even been near one. And yet we still measure them all by this insanely outdated standard as if consumers can actually grasp it.
And watching the damn EV pimps do it with electric motors? That’s not just stupid. It’s d
Re: (Score:2)
Re: (Score:2)
Even horses can't always achieve a horsepower output. You can easily lose your mind in horsepower, especially when you find out there is a difference between US Horsepower (746 watts) and Metric Horsepower (735 watts). (WHY??) And then ask an engine manufacture how they measure the horsepower output of an engine .. measuring torque, multiplying it by RPM and dividing the answer by a magic number .. and of course US and Europe measure torque in slightly different ways which is why there is a Metric Horsepower measurement ...
The kind of insanity that makes a man want to jump on a horse to ride down to the bar for a drink or seven..only to come out hours later to find his horse was taken to an automotive impound lot. Due to local emissions standards.
Re: (Score:2)
"And yet we still measure them all by this insanely outdated standard as if consumers can actually grasp it."
And by "we", you mean the morons that agree with you. Large parts of the world do not use horsepower as a unit.
"And watching the damn EV pimps do it with electric motors? That’s not just stupid. It’s downright embarrassing."
Says the guy who is totally oblivious to just how "downright embarrassing" his own posts are.
Re: Why we should quote EV battery capacity in Jou (Score:2)
The Marketing Problem. (Score:2)
The entire summary essentially proved that watt consumption depends considerably on the specific game and how it stresses the hardware, giving a most extreme example of a game draining the hardware in two hours.
I’d love for the one who wrote that to sell me how they’re going to market that. Battery will last anywhere from 2 to 27 hours, depending on usage? Good luck, because we can’t guesstimate any better than that?
Yeah a kid can do the simple math. Now tell that kid to go market and s
That's a stupid argument (Score:2)
Consumers will not measure the power of their electronics by the maximum current draw on a battery.
A standard for measuring average runtime from full charge is what really matters, mAh only matters when comparing two devices where the only difference between them is battery capacity.
Re: (Score:2)
Re: (Score:2)
Right, no argument there - just like you need to know what kind of power supply your PC build will need based on what you're plugging in to it.
However, for the typical consumer they want to know the case is shinny, it's going to be faster than they're used to, and it's going to last longer than they're used to. They don't understand Watts, amps, or amp-hours or anything else that has to do with moving electrons.
For everyone else, the more meaningful standard numbers we have in the spec sheet, the better.
And yet somehow (Score:3)
Morpheus: "The human generates more bio-electricity than 120-volt battery and over 25,000 BTUs of body heat. Combined with a form of fusion, the machines have found all the energy they would ever need."
"This new power plant will generate 400 megawatts every month, enough to satisfy the energy demands of 27 medium-sized distilleries."
You could also use hogshead per fortnight - the distinction will be lost on most people, because most people are utterly ignorant 1) on basic arithmetic, and 2) what the hell energy and power mean.
This just isn't true (Score:2)
With elementary math, consumers could easily calculate battery life by dividing watt-hours by power consumption.
No, that's not true at all. That's not how computers work, and that's not how batteries work. Battery capacity is not like a spring, where force in and force out are equal. The amount of power that it takes to charge a battery differs depending on how you do it, and the amount of power that you get out also depends on how you draw it.
In general, the slower you discharge a chemical storage battery, the more power you can get out. (The same is mostly true of charging them, but there is more nuance.) The compu
Watt = Joule/second (Score:4, Interesting)
But Watts aren't energy... (Score:2)
Watts is not a measurement of energy (Score:3)
Describing batteries etc in watts is something a school kid would know as ridiculous.
What next? Measuring a coke cans capacity not in mililitres but in mililitres per second? Because thats exactly what they are suggesting here.
Ok... Who let... (Score:2)
Who let the marketing people join Slashdot!?!
FFS! Get out! Do not show your faces here again!
And what about USB-C? (Score:2)
Won't someone think of USB-C? Watts is consistent no matter what voltage your USB-C charger negotiates at. Amps would be meaningless without constantly converting. I have a 50Wh battery and I'm charging at 10W. It will take 5 hours to charge.
Doesn't matter (Score:2)
This is essentially the same argument about converting consumer units in the US to metric. The reason it won't happen is that it doesn't matter. For a non-scientific consumer, the semantics of the unit don't matter. What matters is that the units are consistent over time. That way, the consumer adjusts their own thinking to assign semantics to the numbers for that unit.
Consumers generally won't appreciate the difference between mAh and W. They both some set of widget units. What matters is that 3000 m
Unfortunately ... (Score:2)
With elementary math, consumers could easily calculate battery life by dividing watt-hours by power consumption.
You lost a lot of Americans at, "elementary math". (sigh)
Re:Dumbfucks (Score:5, Informative)
W = V*A. Do the math yourself, it's not that hard.
Actually that maths is impossible in some cases, unless you open the product, because many products don't say what battery voltage is.
Traditionally they were simply talking about the mAh rating of the single Li-Ion cell in the power banks of the early days with a boost converter to give the 5V people needed. Also most Li-Ion cells refer to a nominal voltage of 3.7 or 3.8V which is charged to 4.1 or 4.2V and discharged to whatever the boost converter and over discharge circuit limits are set to. So the mAh rating of a cell may be, say, 3000mAh. So right away the first pet peeve. That is simply 3Ah, saying "three thousand thousandths of an Ampere" is just plain stupid, but you can not seem to tell a marketing type that.
Next problem is the cell may be spec'd for that Ah when discharged to, say, 2.8V where as the circuit may stop boosting at 3.2V, making the actual Ah rating less when used. Then you get losses in the boost converter. So combine those two losses and you might only be getting 70% of the cell's spec. If we were to say the cell has 3Ah based on a nominal voltage of 3.8V that would be 3Ah x 3.8V = 11.4Wh but add in the losses from boosting and limited cell voltage range and you could be looking at only 8Wh. At 5V that is actual 1.6Ah even though the marketing person has insisted that to be labeled and advertised as 3000mA.
About now someone is reading this and thinking "Well actually..." and will come up with different answer. That will merely point out that the current system is flawed. The basic premise proposed, that mobile devices power should be spec'd in watts, is a good idea, regardless of how simple the maths may appear.
Side note: Go to the electronics store as ask the customers there if they know the formula for converting voltage to wattage. I bet the number of people who can do your "not that hard" maths will be rather low.
Re:Dumbfucks (Score:5, Insightful)
Actually that maths is impossible in some cases, unless you open the product, because many products don't say what battery voltage is.
And I don't care for example what the voltage of my iPhone battery is, I just care that it is right for the iPhone so that the iPhone works.
Now imagine Apple uses say 9V batteries. Then some marketing guy who knows a little bit about physics asks "can we replace the 9V battery with a 1.5V battery with 6 times as many ampere hours". And suddenly the Ah are 6 times larger with no benefit for the customer.
On the other hand, "Watt" is stupid as well. My MacBook has a _maximum_ number of watts - if all cores and all GPUs are used, brightness to the max, WiFi on and writiing to the SSD simultaneously. And then you could plug in two iPads and charge them from the MacBook battery. But as I'm typing here, only half of an efficiency core is used, with much fewer watts.
It's basically like specifying your car's fuel consumption as "gallons per hour". If you go through Los Angeles in the night, miles and miles of 30mph streets, your "gallons per hour" are miniscule. Now take the car on a racing track with an experienced racing driver and the "gallons per hour" go through the roof. Miles per gallon is a reasonable way to estimate your cost, and you could do "miles with a full tank" to measure how far you can drive without a refill.
Watt hours is a unit that makes sense.
Re: (Score:3)
So right away the first pet peeve. That is simply 3Ah, saying "three thousand thousandths of an Ampere" is just plain stupid, but you can not seem to tell a marketing type that.
It's only stupid in absolute terms, not in comparable terms. Batteries are compared to batteries. Batteries have a long history with them in being marketed in mAh (because they were small), so users are used to not only the unit, but it benefits not having to do math when making a comparison. It's not just consumers or marketing either. You learn in your engineering degree not to mix units when comparing between things, even if the differences are a factor of a thousand.
It stands to reason that mobile phone
Re: (Score:2, Insightful)
But beyond that, Watts don't make a lot of sense for DC current, you can know the power draw just by looking at the current. No need to confuse things by including the voltage. Amp-hours are fine. With AC you need to include the reactance, which is why it's useful to include the voltage and use watts instead of amps. (That is my understanding, it might be weak).
not really Dumbfucks (Score:3)
But beyond that, Watts don't make a lot of sense for DC current, you can know the power draw just by looking at the current.
... if you know the voltage
No need to confuse things by including the voltage.
...unless you want to know the power draw.
Re: (Score:3)
I'm not sure why you think you can eliminate terms from ohms law. You objectively need more than one term to relate power and current. Either you need to know the voltage and current to determine power being drawn, or you need to know equivalent resistive load to calculate the power.
Same with power loss over cable you need to know either the voltage drop, or the resistance in addition to current. DC isn't different from AC in this regard.
Re:Dumbfucks (Score:5, Informative)
And that's why vendors will never, ever let go of mAh, because they can quote impressively misleading figures at the cell's native voltage even if they're in a 5S2P pack.
On the remote chance the industry does decide to come up with a new rating that isn't mAh, it'll be PMPO, Peak Marketing Power Output, so you can get 1000 PMPO Watts from a recycled 18650.
Where? (Score:2)
Side note: Go to the electronics store
I'm stuck at step one...
Re: (Score:2)
Exactly this, coupled to the transient nature of duty cycle over time. This yields an actual representation of battery drain time, no matter the load (all resistive loads within the system over its duration from fully charged to drained unusable).
And it's tough, a min-max time over the service life of the power source (battery). No one wants to think anymore, let along give an accurate projection needed to make a useful buying decision.
Re: Dumbfucks (Score:2)
We need AI for that now.
Re:Dumbfucks (Score:5, Interesting)
You can't do that if you don't know what the voltage is. I have a power bank here that claims 30,000 mAh. Is that battery current, or 5v port current, or some other current from the variable voltage USB-C port? Or off each individual 3.7v cell in the pack?
Manufacturers can be counted on to be deceptive if you give them the opportunity, which this certainly does. So I assume they are going off the battery cells, which gives them the lowest voltage and so the highest current number to put on their package. But it doesn't say anywhere on the package, so who knows for sure? And if I'm trying to compare two different batter banks for purchase, are they measuring off the same voltage? Though to be fair here, they're probably BOTH going off the battery cell voltage because they both want to advertise the biggest number - if one of them does it then they all have to do it, because consumer are stupid and it'd cost them a lot of sales otherwise.
This is like reading the sticker on the new car in the lot to see what the fuel economy of the car is, and instead of MPG, it's MPT. (miles per tank) It's not an answer you can directly compare to the other cars in the lot, (since tank sizes vary) and requires additional information (capacity of gas tank, which to no one's surprise is NOT listed on the sticker) plus you have to do math to get the number you actually wanted and can use to compare with other products. This theoretical "MPT" is a device selected to cause confusion with the consumer, just like mAh is on real life products like batteries and banks.
Re: Dumbfucks (Score:2)
Watts and watthours makes more sense.
UPS Ratings (Score:2)
W = V*A. Do the math yourself, it's not that hard.
Sure if you're talking about DC. Now calculating the runtime on a UPS that's rated in KVA. Hint: Volt-Amps aren't the same as Watts.
Re: (Score:3)
Well, a VA is the same thing as a Watt. It's the definition of a Watt, in fact.
"Volt-Amps" are a special unit defined such that you can measure it approximately with a simple multimeter or exactly(ish) with a more expensive one, and don't have to do any integration to get the proper result.
Re: (Score:2)
W = V*A. Do the math yourself, it's not that hard.
Unless they don't happen to specify the voltage. Then it IS hard.
As long as battery capacity is specified in watt-hours, power should be specified in watts.
Re: (Score:3, Funny)
Pray tell, what is this "incredibly useful information" that isn't obvious from the watt, unless you're a braindead retard?
Why feed the trolls? (Score:2)
And why propagate their vacuous Subjects?
Re: Dumbfucks (Score:3)
If the user wants to know how long they can use the device, they want the answer in units of time, giving the answer in watts, further hides the information.
Re: Isn't there some proper ancient non-SI unit? (Score:3)
Re: (Score:2)
Re: (Score:2)
Horse-Hour doesn't make any sense because horses wear out if they keep going for an hour.