There're several companies out there that sell "extended" batteries for smartphones. For example, Nokia Lumia 820 standard battery has 1450 mAh capacity and the extended one has 1600 mAh capacity - 9% more.

Now a smartphone typically runs less than one day before the battery is drained. Let it be 20 hours on standard battery which translates into 22 hours on the extended battery.

Either way the phone needs recharging every day.

Does it make any real difference for users?

  • 3
    It could make the difference between the phone running out of batteries on the train on the way home, as opposed to when you actually have arrived home, so yes, I think it does make a difference. Non-functional issues of this nature (speed of use being another such item) are very much User Experience issues.
    – JonW
    Commented Jan 31, 2013 at 9:31
  • But when the battery life goes down- as it inevitably will- the "non-extended" batteries will reach the stage where they need charging more than once a day sooner than the "extended" ones do.
    – Urbycoz
    Commented Jan 31, 2013 at 9:33
  • @JonW: Yes, this scenario is valid, but what are the chances that your trip has exactly the duration that the standard battery is drained but the +9% extended one is not?
    – sharptooth
    Commented Jan 31, 2013 at 9:35
  • 3
    If it were a 100% improved lifespan then we would all agree that there is a noticeable user benefit. I think the question is really about 'at what percentage of additional battery life does the user gain any noticeable benefit over standard batteries'. (But that's probably not answerable in this situation).
    – JonW
    Commented Jan 31, 2013 at 9:46
  • 1
    1600/1450= 1.1034, which translates in 10.3% more, not 9. Also my smartphone easily runs 3 days, 72 hours and a 7 hour increase would be certainly noticable.
    – Pieter B
    Commented Jan 31, 2013 at 14:11

4 Answers 4


Intuitively it seems reasonable to say that you only need the extra battery life if you frequently let your battery run out (implying you do not charge often enough, or long enough). So, how often do people recharge their phones? Is this a problem many people encounter? You might find the 2011 paper by Ferreira et al. interesting. It is titled "Understanding human-smartphone concerns: a study of battery life". They were interested in the recharge behaviour/patterns of smartphone users.

I will quote some parts from the paper as it applies to your question, but you should really read the full paper to get a more complete answer.

Some context from the abstract:

This paper presents a large, 4-week study of more than 4000 people to assess their smartphone charging habits to identify timeslots suitable for opportunistic data uploading and power intensive operations on such devices, as well as opportunities to provide interventions to support better charging behavior.

How do users manage batter life?

Users mostly avoided lower battery levels, with the daily average of the lowest battery percentage values being 30%. This is likely due to the fact that the Android devices’ battery icon turns yellow at 30%, and prompts the user with a textual notification to charge the smartphone by the time it reaches 15%.

How do people fit "charging time" into their daily routines?

The data reveals two major charging schedules: one between 6PM and 8PM, with the majority of users initiating charging when the battery levels are at 40%, and another charging schedule between 1AM and 2AM, with a majority initiating charging when battery is at 30%.

What counts as "charging time"?

By charging time, we mean the time since the user plugged his device to charge until unplugged from the outlet.

How long do people typically leave their phones to charge?

The majority of the charging instances occur for a very small period of time (up to thirty minutes) or between one to two hours, which is the average required time to recharge completely a battery.

however, some people leave the phone plugged in

As expected, a lot of charging instances happen overnight, for 14 hours or more...

How do people charge their phones?

As predicted, for longer charging periods AC is the preferred choice for phone charging. For short charges (30 minutes or less), USB charging is much more frequent. On average, users charge their phones 39% of the time using USB, and 61% of the time using AC...

So, it seems that most people won't necessarily benefit from 9% reserve battery power, given the typical power-management behaviour. The one caveat is what constitutes a "typical user"...

  • That's some comprehensive figures! What surprises me is that one of the main charging periods is between 1AM-2AM. The figures do seem to back that up, but it seems surprising to me that there are significant numbers of people who start charging their phone at 1AM.
    – JonW
    Commented Jan 31, 2013 at 15:29
  • Not having the phone hit a lower battery level constitutes a user benefit. If my phone was regularly hitting 10% (yet never hitting 0%), I would probably want an extended battery.
    – Brian
    Commented Jan 31, 2013 at 15:30

Personally at-least, I can say a firm yes, though not as much as having a second battery (but normally getting an extended battery means you still have the original as well.) It also has a negative impact though, because typically the extended battery alters the shape of the phone. This greatly limits what accessories can be used with the device. Personally, I've still found it worth it on most phone's I've purchased as the extra time frequently means more confidence in my ability to use the phone for what I need without feeling like I'm risking running out of power.

Since having a secondary battery is almost critical these days, unless there is a significant cost difference, the extended battery generally does offer more confidence in not running out of power.

I think the level of impact probably varies greatly from person to person though and from phone to phone depending on runtime. If a phone has really poor runtime, then the extra gain probably won't matter unless it is a higher percentage. If the phone has long enough run time, then it doesn't matter again because it can make it between chargings. If the phone typically has problems making it between chargings without and doesn't with, then it is a significant and meaningful difference in experience.


Reasons to buy a new battery:
1. As a spare battery.
2. Existing battery no longer holds a full charge.
3. Existing battery has insufficient charge for user's usage/charging habits.

In the case of #3, the user probably won't be satisfied with a form-fitting, 10% extended battery and will instead be forced to go with a 100%+ extended battery (which changes the shape of the phone). In the case of #1 or #2, the user will, all else being equal, prefer one which holds more charge. Unless the user is very well-informed, the only things the user is going to pay much attention to when buying a new battery is capacity, price, and reviews.


It makes a difference for my teen-age daughter. I realize that's a single data point, but I bet she's not alone.

By having an extended battery on her iPhone, she tends to use it more every day. Prior to having the battery, she sometimes had to make choices about how much to use during the day based on what her needs for the evening would be.

For example, if she knew she was staying after school to attend a football game, she would conserve battery use during the day so she would be able to call me in the evening to pick her up. The extra battery frees her from having to make such compromises because she can use it almost as much as she wants and it will last until bedtime.

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