SDSD laptops and laptop batteries

[ChrisGreaves]

A thought: back in the day of hard drives⁽¹⁾ - rotating platters - much energy was spent moving arms in and out, starting up, and rotating disks. Not much I grant you; I recall seeing specs of a one-inch disk about twenty years ago. A laptop battery might last eight hours.

Battery technology has improved over the past twenty years, and laptops have done away with kinetic energy and its evil cousin the Associated Entropy.

So why doesn't this HP15 laptop battery last for thirty-six hours?

I suspect that the answer is "economics". Now that laptops don't need rotating-disk energy, the laptops don't need as much energy from a battery, so we can install a cheaper battery that still delivers 7 hours of life.
The battery might just be smaller in terms of its number of atoms of Lithium required, or it might user older technology (Na, K, Rb, Cs or Fr from the periodic table) or something else.

⁽¹⁾ I grew up with 15" diameter 8-platter 8MB disks that were so heavy that at S.A.I.T. female computer operators weren't allowed to lift or mount them on account of the strain ...

(signed) "curious" of Bonavista

[HansV]

One of the main goals in laptop design has been to make them thinner and lighter. So batteries have become thinner and lighter too.
CPUs now have multiple cores, increasing power usage.
Screens with high pixel density, and in particular touchscreens, use more power than the old lower resolution screens.

[stuck]

...Battery technology has improved over the past twenty years...

Yes but battery chemistry hasn't changed that much. That plus the higher energy demands as outlined by Hans will be the main reasons why batteries don't last very long.

Ken

[ChrisGreaves]

@Hans & @Stuck

OK. So we went through a bit of a saddle-point where batteries were becoming more powerful as laptops became more efficient.
"Saddle-point" because each combination of device and battery would produce a different drain-time for a laptop, but once all the hard drives were gone, things would settle out again.
Cheers, Chris