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Joined 2 years ago
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Cake day: June 11th, 2023

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  • Well… sort of.

    Batteries perform differently under load. A battery that delivers 10Wh under a 1W load will probably deliver less (and get warmer) under a 10W load. Power supplies also perform differently under load, and DC-DC switching power supplies perform differently based on the output voltage. Generally, a larger voltage conversion and/or a higher load is less efficient. There’s also going to be some base power consumption in the circuit, so the most output power is probably achieved at some sort of medium load.

    To make things more fun, batteries are usually tested under constant current, not constant power. The increasing current as the battery drains of a constant power load will result in less total power, and constant output power often means increasing input power as the battery drains.

    In short, the real world is complicated. Giving best and worst case Watt-hours could be a reasonable approach.



  • Powerbanks are where it’s most problematic. They’re usually reporting the capacity of the battery cells in mAh. Those cells will be at 2.8-4.2V during operation, but the powerbank outputs 5V, or in modern powerbanks some higher number. 5000 mAh at the 3.6V average of the cells during discharge is certainly not 5000 mAh at the 9V it’s giving to my phone.

    It’s not going to give my phone 2000 mAh @ 9V or 18 Wh as the math would suggest either because it’s well below 100% efficient. I’m not sure what’s reasonable to demand in terms of advertising here since efficiency will vary with output voltage and output wattage.












  • The article only tests whether the batteries get hot. High electrical loads, both charge and discharge can also degrade batteries directly.

    I’ve been setting limits with ACCA for years on my Pixel 4A because its battery is difficult to replace. I didn’t expect to keep it for five years, but there isn’t a new phone I would like better.

    My standard limit is 60% charge and 500mA charge rate. Sometimes I increase the limit to 80% or the charge rate to 1000mA for convenience. I rarely allow 100% or the full 3000mA charge rate, and it’s set to pause charging in response to temperature.


  • With ten finger typing, having the most-used keys on the home row is a significant advantage for speed and ergonomics. With swiping, having a sequence of characters close to each other makes it hard for the algorithm to predict the intended word. With tapping, it’s a disadvantage to have adjacent characters in a sequence on a small touchscreen because it increases the chance of fat-fingering them.