July 18, 2024


Unlimited Technology

Battery Capacity vs. Charging Speed: Which Is More Important?

We’ve said it before, and we’ll say it again: the ideal smartphone battery is one that makes you forget about it. That is to say that it’s something you don’t have to worry about. For instance, if you have to go out of your way to charge your phone to ensure that it won’t suddenly die on you, that’s an instant red flag.

With all these smartphone brands boasting about their super-fast charging lately—from 18W to all the way at 100W or even higher—you’d think charging speed must matter a whole lot more than the total battery capacity. But is that true? Let’s find out.

How Do Smartphone Batteries Work?

Before we get into the details, let’s first learn how batteries work. Smartphone batteries are made of lithium-ion, and they inevitably degrade over time. They work by exchanging electrons between two electrodes: positively charged (cathode) and negatively charged (anode).

When your smartphone is in use (or just simply sitting idle running background apps), electrons from the negative pole flow towards the positive pole. This flow powers the components in your smartphone and allows you to run apps and use services like WiFi, GPS, flashlight, etc.

lithium rechargeable battery

When charging, this flow is reversed, i.e., electrons flow from positive to negative. Now, this is all great until you decide to go from 100%-0% and vice-versa over and over again. This is bad for your battery because the more imbalance the battery holds, the faster it will degrade, reducing its capacity.

Ideally, you want your phone to stay near 50% charge for as long as possible. But this isn’t exactly convenient for daily use. So for an optimal and consistent charging habit, you should keep your battery roughly between 80%-20% and never higher or lower than that range.

Related: The Most Promising Alternatives to Lithium-ion Batteries

Why Do Brands Prioritize Speed Over Capacity?

There are two reasons smartphone manufacturers deliver speed over battery capacity.

One, because including a physically bigger battery makes the device bulkier. When prospective buyers enter a physical store, the first impression matters a lot. In other words, how the device looks, feels, and overall appeal plays a huge role in the buying decision.

A smartphone with a slim look and feel simply appears more modern and gives a premium vibe, attracting attention and sparking interest. Due to this, smartphone brands compete to make their products as visually distinguishable as possible to make a good first impression.

iPhone battery wallpaper

And two, faster charging makes for better marketing material and gives brands bragging rights, so to speak. Most of us don’t like waiting for our phones to charge, so it’s not surprising why we find fast charging compelling; it saves time.

Now, you may argue that people can just charge their phones overnight, and you’d be right. If your phone can last one full day of use, then fast charging seems a bit unnecessary. However, say you’re in a hurry to leave for an important meeting in 30 minutes and your phone is dead. In that case, fast charging can be a godsend.

Misconceptions About Smartphone Battery

A popular misconception is that fast charging can damage your phone’s battery in the long run. While poor manufacturing and fake third-party accessories can certainly be dangerous, fast charging is not as damaging to your device as you might think.

We covered how fast charging affects battery life in a previous article if you’d like to know how the tech works in greater depth. However, in actuality, the bigger threat to your battery is how excessively you use it and its internal temperature, resulting in overheating issues.

Related: How to Check Battery Health for an Android Phone

A smartphone in airplane mode

You must have seen in ads how a lot of brands use liquid cooling to keep a smartphone’s internal temperatures from rising too high. This is because overheating is just straight-up bad news for your smartphone.

Overheating can change the battery’s physical structure and significantly reduce the maximum capacity of charge it can hold over a period. This is the reason why gamer-centric smartphones often have a huge battery capacity to compensate for the overtime degradation since gaming is a power-hungry task.

When to Prioritize Speed Over Capacity


If you travel a lot and don’t stick to one place for long, you absolutely need a fast charger handy because you don’t know when you might get access to a functioning power source again. In such a case, relying on your standard 5W or 10W charger can invite unwanted trouble.

However, for most people, fast charging is more so about convenience rather than about necessity. It’s about that ease of mind that if they ever happen to be running low on battery, they can plug in their device for a couple of minutes and get hours worth of screen time.

Related: How to Charge Your Android Phone Faster: Tips and Tricks

When to Prioritize Capacity Over Speed

We know that fast charging comes in handy when you are running short on time and need some juice right away. However, if you spend most of your time at home or the office, fast charging shouldn’t be your priority when you are in the market to buy a new phone.

Similarly, if you don’t upgrade your phone very often, a physically bigger battery will prove to be more helpful in the long run because it can survive its timely degradation. In other words, a phone with a 5000mAh battery and “normal” charging speed will serve you for more years than a phone with a 3500mAh battery and 100W charging.

There are exceptions to this, of course. For instance, brands can build custom smartphone processors that are highly optimized, efficient, and calibrated specifically to ensure minimal battery usage. This way, a small but well-optimized battery can outlast a big but poorly-built battery. Theoretically, at least.

iPhone 13 Pro battery

Image Credit: Apple

But by a general rule of thumb, the bigger the battery, the longer it will last. And as smartphones increase in power and capability, the need to constantly upgrade to a newer model is becoming less and less obvious. Unless you are an enthusiast, it won’t make sense to buy a new phone if your old one is working just fine.

In fact, users today are holding on to their devices for longer than ever before. And if you are in the same camp and are planning to hold on to your device for more than three to five years, prioritizing battery capacity would probably be a smart choice.

Related: Why Do Phones Have Such Short Battery Life?

Smartphone Batteries Should Be Balanced

Ultimately, there is no clear winner between charging speed and battery capacity. Both have pros and cons. Increase the capacity too much, and the phone becomes bulky. Keep it too little, and the battery will empty sooner. Increase the charging speed too much, and the phone will overheat. Keep it too little, and it wastes time.

Which is more important depends entirely on the person asking the question, their lifestyle, how they use their phone daily, and their budget. That said, smartphone batteries are becoming more intelligent every year. With all the bleeding edge tech we have so far, it’s unlikely that battery life will be a problem on modern phones.

iPhone teardown battery
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