Demystifying Electricity

Published on: Thu Jan 04 2024


In this article, we’re going to go over some of the basics of electricity for your every day life. There will be some physics to be understood in the beginning, but I promise we’ll get to some more practical questions and tips later. So let’s start.

What is electricity

Electricity, in its most basic explanation, is “the presence and motion of matter possessing an electric charge”. Thank you Wikipedia. But sure, all that elecricity is, are electrons in motion, which in turn delivers energy from the outlet to our devices or from the batteries in the devices to the CPU, screen and other hardware components. Now that does not help us in our every day life, so let’s dive into more specific topics of electricity.

We are going to skip the AC vs DC topic, since I do not think that it has any benefits for the questions, that we are going to answer later on.

Electricity Units


Definition: Voltage, often denoted as ‘V’, is the electrical potential difference between two points. It’s the force that pushes electrons through a conductor.

Analogy: Think of it like water pressure in a hose. The higher the pressure, the more water flows through.

Thank you ChatGPT. Insightful as always. Now voltage is pretty important, since it gives you a baseline for how much power you have available to you. If you have a device that needs a certain voltage, you should always try to match it as close as possible.

Some consequences of a voltage that is too low are inefficient operations of the device and possibly permanent damage to the hardware, due to the strain on the electrical components. Sometimes devices will not even start, if they do not receive a certain amount of voltage.

However if you overpower it, as in plug it into way more voltage than necessary, the device can overheat and sustain permanent damage, which in turn can lead to a shorter lifespan.


Definition: Electric current, measured in amperes (amps), is the flow of electric charge. One ampere is the flow of one coulomb of charge per second.

Analogy: It is like the flow rate of water in a hose - the volume of water passing a point per unit time.

Thank you ChatGPT. So amperes, or amps for short, is another fundamental unit for electricity. If we go with the analogy given by ChatGPT, if we think of voltage as the base water flow, you can think of amperes as what comes out of the other end of the hose. The flow / speed of the electrons is influenced by the resistance (Ohm) in that wire. So low resistance means higher flow and high resistance means less flow.

Just like with voltage, too much or not enough amperes can lead to damage or missfunction of the device. That is also the reason why you have circuit breakers in your household. It prevents the wiring from being damaged when the systems are overloaded.


Definition: Electrical power, measured in watts, is the rate at which electrical energy is transferred by an electric circuit.

Formula: Power (W) = Voltage (V) × Current (A)

Thank you ChatGPT. Watt is what you get when you combine watts and amperes. It is kind of what ultimately matters, when you are considering household devices. Now that statement is not fully correct, because there are nuances to consider. But for the sake of this post, which is not speaking to people, who want to design complex electric circuits and just want to know how not to damage their laptop batteries, it is a fine assumption to make.

If we apply this to everyday life scenarios, let’s look at a scenario where you did not bring your smartphone adapater and only the laptop adapter on a trip. While a laptop requires 60-90W to adecuately charge, an iPhone lies around 10-30W. That does not mean that charging it with the laptop adapter for a week will half the lifespan, but at least try to use the correct adapter when you are at home, where your phone is probably charged most of the times.

Practical Example

Charging a laptop with your smartphone usb adapter

Let’s take my macbook m2 14” as an example. As you can see above (ignore the “M3”, the spec for the M2 is the same), you get a 70W power adapter or a 96W for fast charging. If you take a look at the bottom of the laptop it says “20.3V === 3.3A or 20.5V === 4.7A”. Since watts are voltage multiplied by amps, we can calculate that 20.3 x 3.3 = 66.99 and 20.5 x 4.7 = 96.35. If we compare those numbers to the power adapter watts, we can see that they match up quite well - not perfectly, but good enough.

So the tip here: charge your devices with the adapters they came with, or ones with similar output watts.

Practical Tip - The 80/20 rule

Try to keep your charge between 20 and 80% at all times. Sure, if you’re going on a long trip and want to charge it to 100%, go for it. It’s not like one time is going to ruin the battery. Just like a cheat day is not going to ruin your weight.

If you’re wondering why, here’s an analogy:

Think of the battery as a parking area and of the electrons as cars. Charging the battery would be a car finding a parking spot. So when the parking area is completely empty (empty battery), it’s super easy to find a parking spot for any car (electron). But as the parking area gets crowded, it becomes harder and takes more time to find a spot. This is analogous to how a battery is charged.

In the case of an almost empty battery, the speed of the electrons if way greater, which in turn leads to more heat generated in the battery, thereby shortening its life span (entropy, the evil of all things). In the case of a fuller battery, it also requires more voltage to charge, which in turn puts a strain on the battery and shortening its lifespan.

Following this tip, an easy “hack” to extend your smartphone battery life is not charging it every night. Nowadays you can charge a smartphone with fast charging capabilities in a matter of 1-2 hours. So in the evening, get it charged to 100%, use it before going to bed to look at social media to degrade your sleep quality and then do not put it on a charge, but rather have it sit at an >80% level throughout the night.

Common questions

When is charging harmful for your device?

Practically speaking every battery has a finite life span. It is just a matter of trying to get the longest one. That means that ideally, in a perfect world, you would not charge your battery more than 80% and not let it discharge below 20%. You would also not use your laptop in a hot environment where it can overheat.

Also it can not be understated how much better battery and device technology has become in the last decades. For example, most laptops have inbuilt safety mechanisms that prevent overheating the battery when keeping it plugged in at 100% charge. Keeping the laptop plugged in at 100% will degrade the battery over time and shorten its lifespan, but it will not overheat it and potentially cause it to explode or catch fire.

Thankfully a lot of modern operating systems can you give you insights into charging patterns and battery health, so that is something you can monitor yourself aswell every couple of months.

Is emptying your battery good for it?

In short: yes. If you’ve every had an old phone that died even though it still had 10% charge, it might be time to callibrate it by letting it discharge to 0%. This will help the operating system get a better grip on the actual % left in the battery. This is not something you have to do often though, maybe once a year.