Generally Li-ion (3.7V nominal) batteries were used so they could just base it off of current usage rather than power usage and you could get a decent idea comparing between smart phones.
Laptop batteries tend to use an operating voltage of multiple times that (2-cells would use 7.4V-ish, 3-cell would be 10.8 to 11.4V nominal, 4-cell would be 14.8V and so on), but the number of cells can vary wildly per model, so Wh is easier to compare numbers between laptops.
EE Here, I like this answer.
This shit should be all standardised around [micro|milli|Ø|kilo|tera]joules. mAh isn’t even energy, it’s charge!
The vast majority of cell phones use a single-cell Li-Ion battery, so their capacities can be directly compared using mAh. Laptops almost always contain multi-cell Li-Ion batteries, so their capacity cannot be directly compared using mAh (e.g. a 4S battery rated for 2500mAh has more energy than a 3S battery rated for 3000mAh).
So why don’t we use Wh for phones too? Simply because manufacturers would rather advertise a battery size of five thousand mAh (wow, so much capacity!) instead of 19 Wh.
The same issue happens with portable USB battery packs - they’re all advertised in mAh even though they use a wide variety of chemistries and cell configurations internally. What manufacturers do is take the total Wh of the pack and convert it back to the equivalent mAh of a single-cell Li-Ion. It’s annoying, and I really wish they would just use Wh directly.
Laptops predate cell phones in mainstream use. When laptops started, there were a variety of battery types in use with no standard charging voltage so Wh was the fair way to compare.
Cell phones have pretty much always been 3.7v lithium so mAh is a fair comparison and gives a bigger number than Wh.
You could just put it in mWh. BAM, bigger number.
3000 mAh * 3.7V = 11.100 mWh Much bigger. Much better.
I hate mAh… it’s absolutely no information how much energy is inside without taking the voltage into account. If you use directly (m)Wh, you directly have the amount of energy the battery can contain.
The same exact reason ISPs sell bandwidth in Mb/s, instead of the proper unit.
Quite simply, 500Mbit/s sounds a lot more impressive than 0.5Gbps or 62.5MB/s.
It leads to a lot of confusion for customers though, who think their Internet connection is 8 times faster than it is.
Why 5000 mAh rather than just 5 Ah?
Wh is a unit of energy, Ah is a unit of electric charge, basically how many physical electrons passed by.
The voltage of a battery goes down gradually as it is discharged, so getting an accurate value for total energy dissipated is very complicated, as this varies greatly with the discharge profile and other physical factors like the age/health of the battery.
The one thing that stays constant is the amount of electric charge a battery can provide. If it’s old, the voltage of that charge will be lower and go down quicker, but it will be the same total charge.
I agree from a consumer point of view, joules would be a friendlier unit, however it is also a lot easier to game. Electric charge is a much more definite unit in an electrical engineering sense.
If any of what I said is confusing please ask me to clarify, I’m assuming a basic level of electronic literacy but it’s hard to know what knowledge I’m taking for granted as an ex electrical engineer.
Church is meaningless if it’s not provided at a useful voltage though. What people truly care about is usable energy, which is what Watt-hours or Joules tell us. For example, I don’t care if my portable battery pack is 1000 milliamp hours, it’s meaningless unless I also know The battery chemistry used (nominal voltage) and the number of cells so I can figure out the actual potential energy.
Also, as a phone’s battery ages, if I’m not mistaken it truly does hold less “charge”, but I still believe the more useful metric is actual energy stored. That’s how it’s done in the EV scene, you use kWh to see how much energy is left in your battery. As the battery ages, “100%” represents slightly lesser energy (kWh)
it’s hard to know what knowledge I’m taking for granted as an ex electrical engineer.
