By Nicolas Raoul

2016-04-22 06:18:56 8 Comments

When I put my Android device to charge, the lock screen says "Charging slowly":

Android Marshmallow Charging slowly

Is it a particular software setting that tells Android to charge slowly?

How to make Android charge fast?


@Nicolas Raoul 2016-04-22 06:18:56

This is not a software setting: Android is just telling you that the power source you connected the device to is not giving enough electrical power to charge as fast as it could.

It seems that:

  • "Charging slowly" means below 1A (at 5V),
  • "Charging" means between 1A and 1.5A,
  • "Charging rapidly" means more than 1.5A.

The solution is to make more electrical power come to your device:

  • If your computer has Type C port, use this one. This port will most likely also have Power Delivery, which will give you a "rapid" charge.
  • Plug to the wall rather than to a laptop.
  • Try different USB cables.
  • Some adapter/device combinations are better than others (example for Nexus 6P/5X), so use an adapter made specifically for your device if available.
  • Some laptops have different USB ports with different power performances. On my laptop I have 2 USB ports, if I plug in the port on the right Android says "Charging slowly" but if I plug in the port on the left (with the + battery symbol) Android says "Charging", which is better:

SS USB battery laptop

Edit: Please see @beeshyams' answer explaining why charging slowly is actually a good thing when your battery is already quite full.

@Zeiss Ikon 2016-04-22 11:39:46

My experience with my Galaxy S4 (lollipop) is that "Charging Slowly" occurs with all 1A chargers and cables (including computer USB ports), while "Charging" appears only when connected to both a charger and cable that support 2A current. Notable that when using bluetooth and navigation (which uses both GPS and cell location), the phone won't charge fast enough to match drain on a 1A charge system; this seems a very likely reason why 2A chargers and cables were created.

@arni 2019-08-30 08:28:25

Also note that in some cases it might be needed to separately enable USB3 quick charging from computer BIOS.

@Andrew T. 2016-04-22 12:11:37

Other answers have explained about how to make it charging faster, this answer tries to explain more about the threshold that the Android uses.

The charging speed is not configurable; it's just a status that Android shows to let the user knows about it.

When it was first implemented, it's based on the how much current (in milliAmpere) it receives. As shown on the commit log, "Show charging speed on Keyguard", specifically, the config.xml file, the default values were,

<!-- Threshold in micro amperes below which a charger is rated as "slow" -->
<integer name="config_chargingSlowlyThreshold">1000000</integer>
<!-- Threshold in micro amperes above which a charger is rated as "fast" -->
<integer name="config_chargingFastThreshold">1500000</integer>
  • Charging slowly: < 1A
  • Charging: 1A - 1.5A
  • Charging rapidly: > 1.5A

5 months later, the implementation was changed to be based on power (in microWatts) it receives. As shown on the commit log, "Charging speed based on voltage", from the same config.xml file, the default values were,

<!-- Threshold in micro watts below which a charger is rated as "slow"; 1A @ 5V -->
<integer name="config_chargingSlowlyThreshold">5000000</integer>
<!-- Threshold in micro watts above which a charger is rated as "fast"; 1.5A @ 5V  -->
<integer name="config_chargingFastThreshold">7500000</integer>
  • Charging slowly: < 5W
  • Charging: 5W - 7.5W
  • Charging rapidly: > 7.5W

Now, the default values and current behavior (using microWatts instead of Amperes) might be problematic on some devices (e.g. Nexus 5). However, those values are also adjustable by vendor/OS maker, as seen in LineageOS' case.

As reported in Nexus 5's LineageOS Bug Tracker and explained in Nexus 5's LineageOS Code Review,

The default slow charge threshold in the framework is set to 5000000 microwatts. This assumes the devices OEM wall charger output is 1A @ 5V.

The OEM LG Nexus 5 wall charger can only output 1.1A @ 4.8V at its max. Then that is further reduced to around 1A @ 4.3V by the charging driver in the kernel. This results in the lock screen incorrectly displaying "Charging slowly" all the time.

Prior to Nougat, the threshold was based on microAmperes and was set to 1000000, which the charger/device could easily do, resulting in the lock screen displaying "Charging".

This change lowers the threshold from 5000000 to 4200000 microwatts so that wall chargers show "Charging" on the lock screen, returning it to stock Marshmallow behavior.

Note: This threshold only affects what is displayed on the lock screen. It does not affect actual charging current.

@beeshyams 2016-04-22 12:16:04

Thanks +1. The change to milliwatt ties in well with Qualcomm 3.0, IMO, where current and voltage both can be tweaked to get required wattage, earlier it was more of brute force increasing current mainly

@beeshyams 2016-04-22 09:43:12

This is by way of supplementing OP's research with additional relevant inputs

"Charging Rapidly" always is neither desirable nor changing the charger mode user configurable

Why is it not desirable?

  1. Current drawn for charging is not uniform. It varies depending on the stage of charging as can be seen from Figure 1 here

  2. This is reiterated by OEM-see footnote 1

Battery must be substantially depleted; charging rate slows as charging progresses

  1. What this means is that Charging Slowly is not necessarily bad. You should expect and see charging rapidly →Charging → charging slowly transition happen as the charge level increases. This is the nature of charging Li Ion / LiPo batteries.Charging rapidly throughout the charging cycle is pushing power beyond what is needed and would surely ruin your battery- Hint: You will never see an OEM claiming to fast charge from 0 t0 100% in xx minutes. Fast charging typically ends in once the battery is charged in the region of 70%. ( You may need to use an app like Ampere to measure the charging current and the corresponding charging slowly/ charging / charging rapidly to specifically know for your device)

Why is the Charging mode not user configurable?

Andrew's answer explains the associated current and power limits depending on which the mode changes and is android feature. Aside, Samsung has come up with user configurable options to enable/disable fast charging

OK, how do I ensure it is charging rapidly whenever it should?

Options suggested by OP are all valid with a caveat- While mixing and matching cables to maximize current as quoted by you (example for 6P/ 5X from my earlier answer) is a good idea, you need to bear in mind the following

  • Any fast charger won't do, use OEM charger only, if you want fast charging. Nexus 5X uses USB Type C charger not Qualcomm fast charging, though it runs a Qualcomm Chip. Nice write up here

  • If shopping for cables outside Google,make sure they are USB Type C compliant

@Grimoire 2016-04-22 10:42:24

Not sure if this is related, but I found that a five-pin microUSB allows faster charging than a four-pin one.

@beeshyams 2016-04-22 10:57:40

@DeathMaskSalesman: Type C USB being discussed here is 24 pin. 5 pin is for earlier versions supporting OTG. I haven't come across reasons if any that it should charge faster. Please share if you are aware

@Grimoire 2016-04-22 11:06:56

None really, I just compared the charging speed of said cable against the stock Samsung cable.

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