The comments in this question say that I shouldn't wait until low battery charge level before I charge, because that reduces battery life (this is contrary to my understanding before that the faster we charge (without waiting for battery to discharge) the worse it will be for battery life). My question is, when I should generally start charging to avoid this effect? 20%?

Interesting question: If we always limit the usage of the battery only 20% and above, won't we, in effect, reduces our battery capacity to 80%, because we will only use the battery in 20%-100% state?


3 Answers 3


As soon and as often as you can. Spending time at any extreme of charge (high or low) can damage lithium batteries. High charge isn't that bad, considering how quickly modern devices will drain away from that state. Spending time at lower charge levels will damage the internal structure of the battery though.

Draining to "0" on the device won't actually immediately kill the battery though -- the battery protection circuitry will prevent it from going down to critical levels. But the more time you spend at lower charges, the more cumulative damage you do and the more time you take away from the lifespan of the battery. Do the best you can to avoid this, and you'll likely have a battery that still gives you 70-80% of it's life by the time the device is considered obsolete.

  • So you mean I should always connect my phone whenever I have access to a charger or a USB port with cable? Boy I thought this reduces battery life.
    – Fitri
    Commented Dec 23, 2010 at 15:59
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    Yes, connect it every chance you get. It does not reduce battery life. That is only on Nicad batteries and you have a li-ion.
    – Matt
    Commented Dec 23, 2010 at 16:01
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    Exactly - charge whenever you have an opportunity. The only time you're likely to run into a NiCad (last tech that had significant memory effect) is in cheaper cordless power tools.
    – Saiboogu
    Commented Dec 23, 2010 at 16:05
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    ... and some digital cameras. Most of those look like two AA batteries tapped together because they are two nicad AAs taped together.
    – Matt
    Commented Dec 23, 2010 at 16:26
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    No worries about unplugging early - If you can only squeeze in a few percent charge before moving on it's still beneficial and has no downsides.
    – Saiboogu
    Commented Dec 27, 2010 at 13:29

Lithium Ion batteries don't develope "memory" like Nickel Cadnuim batteries, so charging every day regardless of your discharge level will not affect the battery life. If my memory serves me right, because of the way that the batteries are recharged it is less strain on the battery if you don't let it get below 40% but I wouldn't worry too much about it. In that same respect, don't be hesitant to charge anytime you have the opportunity.


Now there's Chargie - a USB stick+Android app combo that limits charging externally (no root needed). Just install the stick between the charger and phone and use the app to select the charge level. Simple as that. Look for "chargie stick" on Google.

Even if you want to charge to 100% - it will go there but disconnect power completely until charge goes down to 97% (a few hours). Then it will reapply charge, but that's way less stressful than normal trickle charging. However, given today's battery capacities, 90% is enough to get you out of most days.

Disclosure: I am the CEO of Lighty Electronics. We developed Chargie and would love people who have had this issue to enjoy our product as much as we do. No spam, just the solution to the problem.

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