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this post was submitted on 14 Sep 2023
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No Stupid Questions
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No such thing. Ask away!
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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.
As always, a relevant XKCD
I can't imagine it's hard to establish a standard environment for battery capacity testing, or that such a standard doesn't exist already. Charge might be the more definite unit but it is not the useful unit. I think the closer they get to actually measuring the battery performance the better
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)