3 ms·

It's also interesting that this low-power mode is sufficiently low power for Apple to be feel comfortable sipping battery power continually. Any guesses about

It's also interesting that this low-power mode is sufficiently low power for Apple to be feel comfortable sipping battery power continually. Any guesses about how much power this mode actually uses?

semi-extrinsic 5y ago
Other Bluetooth LE devices like an AirTag can last beyond one year on a CR2032 battery, so consuming about 2 milli-watt-hours (mWh) per day. An iPhone has at least 10 000 mWh battery capacity (depends on model), so in 1 month something like this consumes around 0.6 percentage points of battery.
- SilverRed 5y ago
  I would think the normal drain of a battery sitting on the shelf is more than this feature uses.
  - coupdejarnac 5y ago
    Exactly, this is pretty much the case.
judge2020 5y ago
the NFC chip probably uses a tab bit more power, but it also uses battery after your phone dies to allow you to continue to pay for transit. "power reserve is available for up to five hours when your iPhone needs to be charged". https://support.apple.com/en-us/HT209495#:~:text=power%20reserve%C2%A0is%20available%20for%20up%20to%20five%20hours%20when%20your%20iPhone%20needs%20to%20be%20charged https://support.apple.com/en-us/HT209495#:~:text=power%20res....
- b9a2cab5 5y ago
  Your phone isn't actually "dead" when it shows out of battery though, since the display can still power on for another hour+. There's a reserve before you hit the true 0%.
  - judge2020 5y ago
    I mean, true 0 would mean the battery couldn't ever charge again. My iPhones have consistently always turned off when the indicator is on 1%, which of course is probably 5% of the actual battery.
    - aroman 5y ago
      > true 0 would mean the battery couldn't ever charge again what?
      - mmis1000 5y ago
        Due to how battery designed. A actually fully discharged battery can't be charged normally.(the power control chip on the battery need a bit power to function normally) Typically this can't happen because your phone will shutdown before that. But if you used up the battery and not charge for a long time (1 months or so). This can happen because batteries discharge themselves slightly even not being used.
        Jensson 5y ago
        Why can't the power control chip also get power from the charging power? That wouldn't be particularly hard to do.
        mmis1000 5y ago
        It turns out my memory is incorrect. The lithium-ion batteries damage itself when the under certain voltage due to how it works. The control chip is there to stop the battery from having too low voltage. However they can't help with self discharging caused low voltage.
      - authorityofnil 5y ago
        Battery chemistry often relies on there being ~some charge. Completely dead battery would be, as the name implies; dead

It's also interesting that this low-power mode is sufficiently low power for Apple to be feel comfortable sipping battery power continually. Any guesses about how much power this mode actually uses?

semi-extrinsic 5y ago

Other Bluetooth LE devices like an AirTag can last beyond one year on a CR2032 battery, so consuming about 2 milli-watt-hours (mWh) per day. An iPhone has at least 10 000 mWh battery capacity (depends on model), so in 1 month something like this consumes around 0.6 percentage points of battery.

SilverRed 5y ago
I would think the normal drain of a battery sitting on the shelf is more than this feature uses.
- coupdejarnac 5y ago
  Exactly, this is pretty much the case.

judge2020 5y ago

the NFC chip probably uses a tab bit more power, but it also uses battery after your phone dies to allow you to continue to pay for transit. "power reserve is available for up to five hours when your iPhone needs to be charged". https://support.apple.com/en-us/HT209495#:~:text=power%20reserve%C2%A0is%20available%20for%20up%20to%20five%20hours%20when%20your%20iPhone%20needs%20to%20be%20charged https://support.apple.com/en-us/HT209495#:~:text=power%20res....

b9a2cab5 5y ago
Your phone isn't actually "dead" when it shows out of battery though, since the display can still power on for another hour+. There's a reserve before you hit the true 0%.
- judge2020 5y ago
  I mean, true 0 would mean the battery couldn't ever charge again. My iPhones have consistently always turned off when the indicator is on 1%, which of course is probably 5% of the actual battery.
  - aroman 5y ago
    > true 0 would mean the battery couldn't ever charge again what?
    - mmis1000 5y ago
      Due to how battery designed. A actually fully discharged battery can't be charged normally.(the power control chip on the battery need a bit power to function normally) Typically this can't happen because your phone will shutdown before that. But if you used up the battery and not charge for a long time (1 months or so). This can happen because batteries discharge themselves slightly even not being used.
      - Jensson 5y ago
        Why can't the power control chip also get power from the charging power? That wouldn't be particularly hard to do.
        mmis1000 5y ago
        It turns out my memory is incorrect. The lithium-ion batteries damage itself when the under certain voltage due to how it works. The control chip is there to stop the battery from having too low voltage. However they can't help with self discharging caused low voltage.
    - authorityofnil 5y ago
      Battery chemistry often relies on there being ~some charge. Completely dead battery would be, as the name implies; dead