When you SHOULD let your phone battery charge to 100%

For the past three years, I’ve been preaching to people to not fully charge their phones, or do it as rarely as possible. Well, all this time it seemed obvious to me (and some other battery-obsessed freaks) that you also shouldn’t let your phone discharge to 0, because it also causes harm to the battery (maybe even more than briefly letting it go to full).

To recap, the three causes that accelerate lithium ion battery degradation are:

  1. heat (while charging or discharging)
  2. prolonged full charging
  3. deep discharging

Chargie protects your battery from the harmful effects of prolonged full charging, but it can’t do anything about deep discharges. Those are to be handled by the user, unless the phone is constantly connected to external power and its charging process completely handled by the Chargie app.

However, there is one instance when you should fully charge your phone: if the battery doesn’t hold a charge until you know you can plug it again.

In those cases, PLEASE charge to 100%, through Chargie, because it will cut off power completely at the top and not keep trickle charging it any longer. This process alone lets the battery’s chemistry relax, the ions to settle and the heat to dissipate in a matter of minutes. Cutting off power completely at 100% also puts most phones into deep sleep, which means the CPU won’t be providing heat to the battery any longer.

Of course, the technique is not as effective as charging to 80%, but is the next best thing to charge limiting. You can also use the delayed charging function (called Top Up Scheduler) in the Android app (coming to iOS this fall) for better results.

We’ve experimented the above with our test phones, and the results have been quite revealing.

You could as well choose to do this manualy – plug in and stay attentive to see when the battery is full, then unplug immediately once it gets there. You can do that, but Chargie does it automatically, and that’s why it’s loved by more than 17000 users worldwide, as of today.

Get your own Chargie at https://chargie.org/chargie-shop/

Comments (09)

    1. 20% would be a good point. If you need go below that, take your phone’s recommendation and switch it to Low Power Mode. It’s very useful and protects the battery. Low current consumption at that level makes for reduced heat dissipation and wear.

  1. That is not correct. Letting a Li-Ion cell sit at 0% does NOT hurt Li-Ion cells, because the phone switches off, before it damages the cell.
    There is no damage at low SOC, but above about 4.0-4.1 Volt
    Watch some Jeff Dahn Videos on YouTube.

    1. Having done many experiments with over-discharging batteries, I can definitely tell lithium ion cells are very sensitive to very low voltages, even for short periods of time. Of course, a modern phone won’t let it drop below 3.3v, but going below 3.5v is by far not optimal for that battery. We’re talking long term effects, because we want to use those batteries/devices for as long as possible.

  2. How about battery packs that are made of more than one cell? Like an iPad.
    These need balancing between the cells which happens by bleeding of energy from the full cell to the not complete one and it happens when 100% is reached and let stay there with trickle for a while.
    This is when BMS usually kicks in, doesn’t it?

    1. those batteries are not charged one at a time. Balancing is only done to series-connected batteries, not parallel ones. As far as I know, iPads have a parallel setup, hence the internal BMS only manages per-pack charging, not individually. If one of them goes bad, the heat sensor and the unit’s basic under/over-voltage circuit will tell that. Anyway, we’ve been saying that a 100% charge is good for calibration reasons from time to time.

  3. I charge to 80% with my Chargie and then go about my day. I use very little battery thanks to my de-googled Android OS not wasting battery reporting back to google so I can usually make it home with 55-60% still remaining. Should I wait until 20% before recharging or is it fine to top off to 80% every night?

    1. You can safely take it to 30% every day. But to be on the safe side, better charge mid range. So I guess a 30-70 is just fine.

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