Does charging a phone on a laptop reduce battery life?

👤 Diwas Poudel    🕒 15 Jan 2023    📁 TECH

A battery is the soul of a mobile phone. There’s no life to it without a battery. The battery supplies power to a phone for it to operate. So, taking care of the phone’s battery health is essential. We charge our phone’s battery quite often. Using a phone charger to charge the phone is the most common way. Other ways include using a power bank or a laptop. These methods can work equally well for smartphones. In this article, we will be busting our myths about charging a phone on a laptop.

How can you charge a phone on a laptop?

Charging a phone on a laptop is quite an easy task. You need a USB cable to be connected to the laptop and the phone. The laptop's USB port is supplied with specific power for data transmission. This power charges your phone when connected to the laptop. The USB cable that comes along with the charging brick (charger) gets the job done.

Charging Phone on laptop
fig. Charging Phone on laptop

A different generation of USB ports provides different power supplies. Generally, the maximum wattage that different generations of USB cables provide are:

  • USB 1.0 = 1.5 W
  • USB 2.0 = 4 W
  • USB 3.0 = 6 W

Most mobile chargers today, supply more than 10 W of power while charging a smartphone. Some smartphone chargers can support a power supply of up to 210 Watts until now.

Charging a phone on a laptop is slow

As mentioned above, different generations of USB ports have different power outputs. So, charging speed differs. On comparing the charging speed of smartphone chargers to charging on a laptop, using the charger is way faster. This is because of the low output power provided via the USB ports to the phone. Charging technology has become more advanced day after day. Some smartphones can charge from 0% to 100% within 10-20 minutes. But, fully charging a phone on a laptop can take hours and hours.

Does charging a phone on a laptop reduce battery life?

You must have heard that charging the phone on a laptop or PC reduces battery life. This is just a myth. 

Let us first be familiar with how a smartphone battery works. Almost all smartphones today use Lithion-ion batteries. The Li-ion battery has two electrodes: positive and negative electrodes. Lithium acts as the positive electrode while the negative electrode is made up of carbon. You turn the phone on. The Lithium electrons flow from the negative electrode to the positive electrode. Thus, electric power is generated and supplied to every part of the phone. Now, for charging, the process is reversed. The Lithium ions flow from the positive electrode to the negative electrode. Hence, the charge is restored.

The higher the power supply from the source, the faster the rate of charging. As you now know, the supply from the laptop’s USB ports is low. The rate of flow of Li-ions from the positive electrode to the negative terminal gets slow. Thus decreasing the charging speed. On the other hand, smartphone chargers have a higher power supply. This in turn increases the charging speed.

However, it is more advantageous for a smartphone to slowly charge than to fast charge. When the charging is slow, there’s less strain on the battery. The charging and discharging cycle is slow. The Li-ions have less strain. This reduces the strains on electrodes and other components. But, when the phone is charging fast, there’s more strain on the Li-ions. Therefore, slowly charging a phone is always a better option. Charging a phone on a laptop is not just harmless, but is good as well. There’s no effect on the phone’s battery life. 

Advantages of charging a phone on a laptop

We have now come to know that charging a phone on a laptop is actually good. Let’s now see other advantages of charging a phone on a laptop:

  1. As a laptop acts as a power bank, charging the phone using the laptop can be easy and convenient. In case you don’t have a charging brick or a charging socket, you can opt to charge on a laptop.
  2. Data Transfer - You can do two tasks when the phone is plugged into the laptop’s USB port. At the same time, you can charge your phone as well as transfer your data to and from your laptop.


Charging a phone on a laptop can be easy and convenient but it comes with some cons. 

  1. The charging speed of the phone is too slow when charging with a laptop.
  2. When plugged into someone else’s laptop, your files and folders may be visible to the owner. (However, many smartphones provide a few options, like charging only and charging with file transfer. You can set your phone to a charging-only option when connecting to someone’s laptop.)
  3. The probability that your phone gets a virus also rises if you frequently use your laptop to power it.
  4. Some people believe, not supplying enough power to the smartphone is bad for the battery. But, the effect is very minimal and can be unnoticed.
fig.Different USB Connection Options

What can we do for the good battery life of a phone?

Several factors affect the battery life of a phone. You can follow the instructions below for the longevity of battery life.

  1. The phone’s battery is susceptible to damage when frequently charging. Charging the phone from around 20-30% to around 80-90% is considered the ideal way of charging. Plugging your phone into the charger quite often causes more strain on the battery. 
  2. Don’t keep your phone in high-temperature areas. Keeping the phone in a high-temperature area not just affects the battery, but also degrades the overall performance.
  3. Don’t charge your phone by placing it on other electrical appliances. Many electrical appliances emit electromagnetic waves. Also, they heat up. So, never place your phone on any electrical appliances while charging.
  4. Avoid using chargers from unauthorized manufacturers. 


We have come to know that, there’s no significant damage to the phone’s battery life when charging on a laptop. In this article, we have also covered the advantages and disadvantages of charging a phone on a laptop. Charging the phone using the original charger is always the best practice. However, there’s no harm in charging it on a laptop.

Article by: Pragyan Bhattarai