3 ms·

This chart is a little suspicious given that iPhone battery density has only increased by 20% in 9 years. https://twitter.com/Alxbk/status/1181307722991652864

This chart is a little suspicious given that iPhone battery density has only increased by 20% in 9 years. https://twitter.com/Alxbk/status/1181307722991652864 https://twitter.com/Alxbk/status/1181307722991652864

zardo 5y ago
Apple isn't going to be selecting for mass/energy density. That's a major concern for EVs, but for a phone, you would gladly take double the capacity for 3x the mass.
- magila 5y ago
  EV battery capacity hasn't exactly been skyrocketing either. When the Tesla Model S was introduced in 2012 the largest battery option was 85 kWh. For the 2015 model year it got a 90 kWh option and 100 kWh for 2016. Today 100 kWh remains the most you can get.
  - zardo 5y ago
    How has the mass changed? If we're talking about a fraction (density) it's pointless to talk about the numerator on its own.
    - magila 5y ago
      I can't find any indication that the weight of Tesla batteries has changed significantly since the introduction of the 100 kWh pack. In any case weight savings on Tesla batteries seems to have come primarily from improved packaging rather than better chemistries.
robocat 5y ago
Mobile phones mostly optimise for Wh/m³ or for batteries more usually stated Wh/L (stored energy by volume), however that tweet is about Wh/kg (stored energy by weight) which is less relevant to mobile phones. “Density” means one thing that has little to do with energy, “energy density” https://en.wikipedia.org/wiki/Energy_density https://en.wikipedia.org/wiki/Energy_density is a slightly better term but it is also misused. “volumetric energy density” versus “gravimetric energy density” are clearer terms (edit:) for usage in conversations like this, although the more standard industry terms afaik are “energy density” for volumetric and “specific energy” for gravimetric.

3 ms·

This chart is a little suspicious given that iPhone battery density has only increased by 20% in 9 years. https://twitter.com/Alxbk/status/1181307722991652864

by RivieraKid 5y ago

zardo 5y ago
Apple isn't going to be selecting for mass/energy density. That's a major concern for EVs, but for a phone, you would gladly take double the capacity for 3x the mass.
- magila 5y ago
  EV battery capacity hasn't exactly been skyrocketing either. When the Tesla Model S was introduced in 2012 the largest battery option was 85 kWh. For the 2015 model year it got a 90 kWh option and 100 kWh for 2016. Today 100 kWh remains the most you can get.
  - zardo 5y ago
    How has the mass changed? If we're talking about a fraction (density) it's pointless to talk about the numerator on its own.
    - magila 5y ago
      I can't find any indication that the weight of Tesla batteries has changed significantly since the introduction of the 100 kWh pack. In any case weight savings on Tesla batteries seems to have come primarily from improved packaging rather than better chemistries.
robocat 5y ago
Mobile phones mostly optimise for Wh/m³ or for batteries more usually stated Wh/L (stored energy by volume), however that tweet is about Wh/kg (stored energy by weight) which is less relevant to mobile phones. “Density” means one thing that has little to do with energy, “energy density” https://en.wikipedia.org/wiki/Energy_density https://en.wikipedia.org/wiki/Energy_density is a slightly better term but it is also misused. “volumetric energy density” versus “gravimetric energy density” are clearer terms (edit:) for usage in conversations like this, although the more standard industry terms afaik are “energy density” for volumetric and “specific energy” for gravimetric.