How Do You Know When A Portable Charger Is Fully Charged?

how to know if portable charger is fully charged

Power banks and portable chargers are great for anyone on the go who needs to charge up their battery when they don’t have access to a wireless charger or wall socket.

To tell you the various states of the unit, the chargers have LED light indicators and these are what help you identify whether the charger is fully charged or not. Decoding the information provided by these indicators is also helpful in using the portable charger or power bank safely.

We have written this article to tell you about what these LED indicator lights mean and how to use them to work out when your portable charger is charged.

Common LED Indicator Lights And Functions

Some power banks have 4 LED indicator lights which are blue and when you connect them to load it up, one of these lights will blink and indicate the power bank is starting to charge up.

When you are connected to a power source, the LED lights on your power bank should tell you the charge taken up by the power bank until now.

  • 1st Light Blinking- Charged between 0%-25% and continuing to charge
  • 2nd Light Blinking- Charged between 25%-50% and continuing to charge
  • 3rd Light Blinking- Charged between 50%- 75% and continuing to charge
  • 4th Light Blinking- Charged between 75%-100% and continuing to charge
  • 4 Lights Lit- Fully Charged
  • 4 Lights Blinking- Charging Error

When all the lights are lit and the power bank is fully charged, it should be disconnected from the power source.

Although power banks have a built-in protection system that stops the device from overcharging or overheating, it’s still not advisable to keep the power bank connected to the power source longer than it needs to be as it could cause long-term damage.

When all 4 LEDs start to blink, this indicated that the unit has developed a fault. This should be looked at by a professional and if it is still under warranty, it should be sent back to the vendor to be repaired or replaced.

When the power bank is disconnected, there should not be any LEDs lit but to check the charge level, click the check button which is usually located on the side and you should see either 1, 2, 3, or all 4 LED lights come on.

If all 4 lights turn on, this means the power bank is fully charged and if 1, 2, or 3 LED lights come on, this indicates it is charged to the percentages outlined above. If no LED lights turn on at all, this means the power bank is completely discharged.

Power Banks That Have Two LED Indicator Lights

Some power banks only have 2 LED lights. This will usually take the form of one blue and one red. When charging if the blue light is steady, the power bank is charging the phone but if it is flashing, the power bank needs charging.

If the red light is flashing, the power bank is being charged, but if it is steady, it is fully charged.

Power Banks Without Indicator LEDs

Power banks that don’t have any LED lights will usually be low-cost and lower quality. The manual should tell you how long it takes to charge and as you use it frequently, you should be able to work out charging time yourself.

Faulty LED Indicator Lights

To work out if the power bank has stopped working when the LED indicator lights are faulty or have failed, you will need to test it for yourself. Load it up with charge and then attempt to charge your phone.

If your phone is charging, then your power bank also has a charge and is working properly.

You can also work out the state of charge on any power bank by measuring the terminal voltage of the batteries by a voltmeter.

Most power banks use lithium-ion batteries and when they are fully charged, you will find their voltage should be at 4.2 volts.

How Do I Calculate Charging Time?

How Do I Calculate Charging Time

To do this, you need to find out the capacity of your power bank. This is commonly written on the power bank itself but if you can’t spot it on the power bank, you should be able to find it in the manual.

This will be in mAh which is short of milliampere-hours. Now you need to work out how much current can be delivered by the power source in Amperes and this should be written on the power charger.

If your power bank 10000 mAh capacity and the power charger can deliver a current of 2 Amperes. 1000 mA = 1 Ampere and ‘h’ indicates the time in hours. The time to fully charge your power bank would then be 10000 mAh/2A= 10 Ah/2A = 5 hours.

Some manufacturers of power banks however overstate the charge holding capacity and this would make the calculations outlined above incorrect. You would instead use the actual power capacity formula, which is:

3.7V x Advertised capacity x efficiency / 5V

You also need to consider that power bank charging capacities are reduced over time with heavy usage. You will see a visible difference in the charge holding capacity of your power bank after around 100 to 500 charge/discharge cycles.

However, this will depend on the brand, quality, and durability of your power bank.
If the power bank is subjected to high temperatures, this might also decrease charge capacity.

To work out how much charging time your power bank has left, you can use the first formula outlined in this section with the reduced charge holding capacity.

Damaging Your Power Bank

To extend the life of your power bank, you need to take good care of it and avoid overcharging it or completely discharging it. If you do both of these things regularly, it will discharge beyond the critical level and become damaged in the process.

You need to make sure you are charging your power bank every few months, even if you do not use it that that much. Like any electrical item, avoid leaving or storing your power bank in hot or humid conditions.

Final Thoughts

Using a portable charger or power bank is a great way to extend battery life on the go and to make sure you are never without your phone on trips away.

However, to make good use of a power bank, you need to make sure you are charging it correctly and know what the LED light indicators mean so that you can use them to know when your power bank is fully charged.

This will avoid damage and will extend its overall life to keep you fully charged on the go for longer.

Brett Jones
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