4 ms·

When a battery is as its discharged, its ESR rises, causing this behavior. A small amount of damage is caused during the cycling of a battery, permanently raisi

When a battery is as its discharged, its ESR rises, causing this behavior. A small amount of damage is caused during the cycling of a battery, permanently raising its ESR, so that is why older batteries shut down sooner. Basically, you can think of it as a 5L bucket of water with a hole in the bottom. The first liter will have a much higher pressure than the last. Running energy intensive features (GPS, 3D, camera, cell modem, etc) increases the minimum needed pressure, causing the device to shutdown when lower power features would operate just fine. As you keep using the bucket, the mound of dirt its on gets washed away, reducing the maximum pressure you can get out of it. Building a good battery gauge is non-trivial as you have to factor in how much people use high energy features when the battery is nearing end of charge. Better low power modes would help with this, but nobody has found a good way of indicating to the user the battery has X% power left at current use vs the battery has Y% of its fully charged capacity remaining.

nradov 10y ago
It would be nice if smartphones would degrade more gracefully. The instant that the protection circuit detects that the battery is no longer unable to supply enough power I would think it could immediately shut down all extra peripherals and go into ultra power saving mode (grayscale screen, no sensors, no apps, only phone calls and SMS).
- extrapickles 10y ago
  The ultra low power mode might not be able to do SMS or phone calls over cellular as it needs large bursts of power to TX, depending on connection quality and type (2g vs LTE, range to tower, etc). A capacitor that can store enough charge to send/receive a SMS would allow this to work as the capacitor can be charged slowly, but it would take up valuable room inside the phone (a few mm^3). Some embedded cell/sat radios where size isn't very important already do this to reduce demands on the hosts electrical system (eg: solar powered parking meters that take credit cards).
  - nradov 10y ago
    The ultra power saving mode on Samsung phones does SMS and phone calls over cellular. That is an existing product feature, the problem is just that it doesn't automatically switch to that mode when the battery still has some charge but isn't capable of putting out enough power to sustain normal operations.

nradov 10y ago

It would be nice if smartphones would degrade more gracefully. The instant that the protection circuit detects that the battery is no longer unable to supply enough power I would think it could immediately shut down all extra peripherals and go into ultra power saving mode (grayscale screen, no sensors, no apps, only phone calls and SMS).

extrapickles 10y ago
The ultra low power mode might not be able to do SMS or phone calls over cellular as it needs large bursts of power to TX, depending on connection quality and type (2g vs LTE, range to tower, etc). A capacitor that can store enough charge to send/receive a SMS would allow this to work as the capacitor can be charged slowly, but it would take up valuable room inside the phone (a few mm^3). Some embedded cell/sat radios where size isn't very important already do this to reduce demands on the hosts electrical system (eg: solar powered parking meters that take credit cards).
- nradov 10y ago
  The ultra power saving mode on Samsung phones does SMS and phone calls over cellular. That is an existing product feature, the problem is just that it doesn't automatically switch to that mode when the battery still has some charge but isn't capable of putting out enough power to sustain normal operations.