# Smartphone Charges Faster If I Use It While It's Charging **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [April 18, 2022, 10:25pm UTC](https://boards.straightdope.com/t/smartphone-charges-faster-if-i-use-it-while-its-charging/963014 "2022-04-18T22:25:18Z")\ **Posts on this page:** 9\ **Page:** 2
**Author:** ![pjd](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pjd/32/3009_2.png) [@pjd](https://boards.straightdope.com/u/pjd)\ **Post date:** [April 19, 2022, 11:43am UTC](https://boards.straightdope.com/t/smartphone-charges-faster-if-i-use-it-while-its-charging/963014/23 "2022-04-19T11:43:59Z")
this. ---
**Author:** ![Turek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/turek/32/18782_2.png) [@Turek](https://boards.straightdope.com/u/Turek)\ **Post date:** [April 19, 2022, 11:51am UTC](https://boards.straightdope.com/t/smartphone-charges-faster-if-i-use-it-while-its-charging/963014/24 "2022-04-19T11:51:52Z")
> [@dougrb](#): > > It’s probably just downloading the power. Agreed. The OP should probably write up a paper and send it to some scientists. ---
**Author:** ![echoreply](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/echoreply/32/3641_2.png) [@echoreply](https://boards.straightdope.com/u/echoreply)\ **Post date:** [April 19, 2022, 2:40pm UTC](https://boards.straightdope.com/t/smartphone-charges-faster-if-i-use-it-while-its-charging/963014/25 "2022-04-19T14:40:02Z")
> [@Joey\_P](#): > > use a killawatt type device meant to be plugged into USB ports I have one of those, but there are a few problems with it. A bit of background: Not all USB cables are created equal; some can carry more current than others. I originally bought the USB ammeter to determine which of my big pile of USB cables were best for charging. The problem is, that using the ammeter with a known-good QuickCharge cable, may cause the phone to drop out of QuickCharge, but other times the ammeter will show the phone is QuickCharging. It causes even more problems with Apple devices. The Kill-a-Watt may show an ipad is charging at 10W, then connect the USB meter, and now it is only charging at 5W. The Kill-a-Watt and the USB ammeter tend to agree. Obviously the Kill-a-Watt shows 110-120 volts, but if it shows 10W, then the USB shows 5V and 2A. There is definitely power loss in the charger. The Kill-a-Watt may show 28-30W, but the USB shows 12V 2A QuickCharging. I would like to get a new USB ammeter that does USB-C power delivery, but you go to Alieexpress, look at the hundreds of options, and tell me which one to get. Lots of nearly identical ones ranging from $10-50. I don’t want another one that is so bad it decreases the charge speed when connected. Or go to Amazon and see the exact same ones, but marked up 3-400% and a bunch of fake reviews (if any reviews). ---
**Author:** ![DavidNRockies](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/davidnrockies/32/6279_2.png) [@DavidNRockies](https://boards.straightdope.com/u/DavidNRockies)\ **Post date:** [April 19, 2022, 2:56pm UTC](https://boards.straightdope.com/t/smartphone-charges-faster-if-i-use-it-while-its-charging/963014/26 "2022-04-19T14:56:06Z")
Just a WAG, but this one sounds like what used to be (still is ?) called a surface charge: > [@](#): > > ### **Surface Charge** > > Lead acid batteries are sluggish and cannot convert lead sulfate to lead and lead dioxide quickly during charge. This delayed action causes most of the charge activities to occur on the plate surfaces, resulting in an elevated state-of-charge (SoC) on the outside. > > A battery with surface charge has a slightly elevated voltage and gives a false voltage-based SoC reading. To normalize the condition, switch on electrical loads to remove about 1 percent of the battery’s capacity or allow the battery to rest for a few hours. Turning on the headlights for a few minutes will do this. Surface charge is not a battery defect but a reversible condition. [**SOURCE**](https://batteryuniversity.com/article/bu-804c-acid-stratification-and-surface-charge) ---
**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\ **Post date:** [April 20, 2022, 2:37am UTC](https://boards.straightdope.com/t/smartphone-charges-faster-if-i-use-it-while-its-charging/963014/27 "2022-04-20T02:37:43Z")
That doesn’t apply to the lithium batteries in a phone. ---
**Author:** ![gnoitall](https://avatars.discourse-cdn.com/v4/letter/g/bb73d2/32.png) [@gnoitall](https://boards.straightdope.com/u/gnoitall)\ **Post date:** [April 20, 2022, 3:11am UTC](https://boards.straightdope.com/t/smartphone-charges-faster-if-i-use-it-while-its-charging/963014/28 "2022-04-20T03:11:04Z")
A phone using lead-acid batteries would weigh about 15 pounds and be about the size of a small shoebox. ---
**Author:** ![DavidNRockies](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/davidnrockies/32/6279_2.png) [@DavidNRockies](https://boards.straightdope.com/u/DavidNRockies)\ **Post date:** [April 20, 2022, 3:17am UTC](https://boards.straightdope.com/t/smartphone-charges-faster-if-i-use-it-while-its-charging/963014/29 "2022-04-20T03:17:47Z")
> [@Princhester](#): > > That doesn’t apply to the lithium batteries in a phone. > [@gnoitall](#): > > A phone using lead-acid batteries would weigh about 15 pounds and be about the size of a small shoebox. Ah. Good points. Thank you both 🙂 ETA: a quick review shows it may not be limited to lead-acid batteries. It may be _largely_ applicable to them, though: > In simple terms, surface charge is the situation where your battery reads more voltage than its actual voltage. As a result of the elevated voltage, your battery reads a false voltage. **Battery surface charge happens mainly on lead-acid batteries.** This happens because lead-acid batteries are slow at converting lead sulfate to lead and lead dioxide during the charging process. As a result of this delayed action, most of the charging activity happens on the surface of the plates which results in the state of charge (SoC) increasing on the outside. [bolding mine] Anybody know for sure ? [**SOURCE**](https://www.large.net/news/8xu43qb.html) ---
**Author:** ![CaveMike](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cavemike/32/16379_2.png) [@CaveMike](https://boards.straightdope.com/u/CaveMike)\ **Post date:** [April 20, 2022, 4:03am UTC](https://boards.straightdope.com/t/smartphone-charges-faster-if-i-use-it-while-its-charging/963014/30 "2022-04-20T04:03:57Z")
I don’t think so, but I really don’t know for sure. However, reading the voltage of a lithium battery during charging isn’t accurate because the increased temperature during charging affects the voltage reading. You have to let the battery sit with an open circuit to get a good reading. Instead devices (phones, laptops) typically use a process called coulomb counting to track the current going into and out of the battery. There is a look-up table to map the count to battery percentage. It is possible for the count to get out-of-sync with the battery (due to a bug, a battery swap, etc). In this case, the phone might think the battery is more charged than it actually is. I am not sure what technique earbuds (like the Bose ones upthread) use though. ---
**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\ **Post date:** [April 20, 2022, 4:34am UTC](https://boards.straightdope.com/t/smartphone-charges-faster-if-i-use-it-while-its-charging/963014/31 "2022-04-20T04:34:22Z")
I have never seen lithium batteries exhibit surface charge effects. Surface charge affects otherwise good batteries and causes a slightly elevated voltage that is reduced within moments when load is applied. I have never seen this in a lithium battery. And even if it applied, as **CaveMike** says smartphones don’t use voltage to determine level of charge anyway. So it wouldn’t give the result the OP reports even if it existed in Lithium batteries. [Previous page](https://boards.straightdope.com/t/smartphone-charges-faster-if-i-use-it-while-its-charging/963014.md?page=1)