We live in a fast paced world where we move from one place to another constantly, along with having a plethora of mobile devices we need to carry.

These mobile devices use many different types of rechargeable batteries to keep them energised, but the most common being Lithium-Ion.

Lithium-Ion batteries need to be charged once they have fully discharged. 

But, more often than not, you might need to use the device that has a lithium-ion battery when charging it. 

So, can you charge a Lithium-Ion battery while using it? Yes, you can charge a Lithium Ion battery while using it, however, it’s not the best practice. Doing so will result in a lower rate of charge which means it will take longer to charge the lithium ion battery. 

There are some other issues that arise when trying to charge a lithium battery while using it which shall be discussed further in this article. 

Deeper look at how a battery is charged

Knowing the process of how a battery is charged, will help you better understand why using a Lithium-Ion battery while charging it isn’t very ideal.

There are two main classes of batteries; Primary and Secondary.

Primary batteries are one-off batteries that must be disposed of after they have fully discharged. These types of batteries can only be used once.

Secondary batteries are rechargeable. This means that when they have been fully discharged of all their energy, they can be ‘recharged’ back to their full capacity and used again. 

A Lithium-Ion battery is a type of rechargeable battery. 

They can be recharged multiple times, and their lifespan is largely dependent on their chemical composition.

How a battery charger charges a battery  

But, rechargeable batteries do not just recharge by themselves (which would be neat if they could). However, they require the aid of a battery charger.

Batteries power devices by converting stored chemical energy into electrical power (which is a product of voltage and current). 

The process when a battery releases its energy to power devices is known as discharging. While reversing the discharging process and giving energy back to a dead battery is known as recharging.  

Charging a battery involves a number of steps which include;

  • Charging
  • Stabilising (optimising the charging rate)
  • Terminating (knowing when to stop the charging process)

Charge and Discharge rates of batteries vary from one to the next depending on factors such as their chemical compositions and size (the amount of charge they are able to hold for their given physical size).  

Discharging involves the release of electrons when a chemical reaction occurs in between the two terminals (or electrodes) and electrolyte (the substance that separates the electrodes). 

Once the chemical reaction within the battery is over, the battery is effectively out of charge (flat).

For primary (disposable) batteries this is the end of the road, however, rechargeable batteries can be recharged to be used again.

Battery chargers are used to reverse the chemical reaction process to recharge the battery. While discharging involves energy leaving the battery, charging a battery involves feeding energy back into a battery (using a battery charger) to reset the chemicals to their initial state. 

To feed energy back into a battery, battery chargers supply electric current for a predetermined period of time. 

Reasons not to charge a Lithium-Ion battery while using it

It might seem that a battery charger has a simple task of just feeding current to a Lithium-Ion battery to recharge it.

However, there is a bit more that happens within the battery charger to ensure that the battery is optimally charged while also being protected. 

So it might not be the best idea to charge a Lithium-Ion battery while using it. 

Let’s take a look at why. 

There are a couple of things that happen when you try to charge a Lithium-Ion battery and use it at the same time.

Reason #1 not to charge a Lithium-Ion battery while using it

Firstly when a battery is being charged, it is subjected to a voltage higher than its own. This is why current flows from the battery charger to a battery.

If you try using a Lithium-Ion battery while it is charging (for low currents), you could trigger safety circuits as it may detect the extra current as an overcurrent or short, and stop the charging process. 

For higher currents, the load will draw power from the battery charger which means that the battery isn’t going to get much current and is going to charge at a slower rate taking it a longer time to reach full capacity. 

Reason #2 not to charge a Lithium-Ion battery while using it

The second issue that arises is that every now and then, the battery charger stops charging to monitor the voltage of the Lithium-Ion battery. 

When this happens, the battery will start supplying current to the load which isn’t an ideal situation as the Lithium-Ion battery will then report a different voltage when subjected to a load, as opposed to when not under load circumstances. 

This messes up the charging process.

Can you charge a Lithium battery while using it for consumer electronics? 

The scenarios we have discussed above have mostly been with Lithium-Ion batteries that are detachable from devices (like power tools for example), where the battery charger is a separate entity.

But, many consumer electronic devices (that use Lithium-Ion batteries), have their charging circuits embedded in them.

Devices such as smartphones, smart watches, laptops, and so much more. 

These devices have come a long way, and include sophisticated charging circuits within them. 

Most of the time you would have used one of these devices while you were simultaneously charging it as well.

But, how is this possible?

These devices have been designed with charging circuits that allow one to use it and charge it at the same time. 

Engineers would have realised that sooner or later, the user would need to use their device (especially smartphones) when charging.

Note, while it may be possible, it is still not advisable to do so as you will still be slowing down the rate of charge.

What is the best way to charge a Lithium Ion Battery?

As we have just learnt, charging a battery and while using it is not good practice. Doing so will reduce the rate of charge which means it is going to take longer for the Lithium-Ion battery to reach full charge.

To charge a Lithium-Ion battery more efficiently, follow the three tips below;

  1. Do not use the battery while it is charging
  2. Do not charge the battery under extreme temperatures (cold or hot). Stay within moderate temperature settings
  3. Avoid fully charging the battery (especially with Lithium-Ion batteries). A partial charge will extend its lifespan 

For consumer electronics like smartphones, turn the device off and then charge. This will drastically reduce the charge time. 

Categories: Batteries