Why Are Power Banks Heavy?


a bulky high-capacity power bank displayed on a digital scale

Power banks are a part of everyday life, helping you charge your devices on the go. But have you ever wondered why most of them weigh so much?

Most power banks have standard 18650 lithium-ion batteries in them. Those batteries have a fixed energy capacity and density and weigh approx. 1 ounce each. The higher the power bank’s capacity, the more batteries will have to be put into it. Hence, the weight of the power bank increases.

In addition, power banks also have to introduce an electrical circuit to amplify the power and charge optimally. The protection circuit, power requirement, and amplification circuit together make most of the power bank models that are available today somewhat bulky.

Keep reading this article to learn about all the factors that can make power banks heavy.

Why Are Power Banks so Heavy?

Most power banks use lithium-ion batteries. Lithium-ion batteries have an energy density of 100 to 265 Wh/kg. They deliver up to 3.6 volts. This means that power banks with a higher capacity will have to be packed with more lithium-ion batteries.

So, the higher the capacity, the heavier your power bank will be.

Power banks generally use 18650 lithium-ion batteries. Each of them weighs approximately 1 ounce (45g). Most power banks today contain between 6 and 12 of these batteries.

Irrespective of whether your power bank’s batteries are connected in series or parallel, there is always the need to bulk up the batteries for better energy efficiency. Because of the necessary circuits for amplification and protection, the overall weight and often also the size of the power bank increases

Keep the following in mind before buying a power bank: The larger and heavier the power bank, the higher its capacity will be. Having to carry around a heavy and bulky power bank can be inconvenient for some. On the other hand, a lighter and smaller power bank won’t have the same charging capacity.

How Much Do Power Banks Weigh

On average, the capacity to weight ratio is 1750mah per ounce. Power banks in the 10.000mAh to 15.000mAh typically weigh between 5 and 11 ounces (150-300g).

Power banks with a capacity of 15.000mAh to 20.000mAh usually weigh between 11 and 18 ounces (300 and 500g).

That’s why high-capacity power banks of 40.000 to 50.000mAh can actually weigh more than 30 ounces (900g). You can charge plenty of devices with that much power, but you will have to consider the weight factor and decide whether or not the extra weight is worth carrying around.

Personally, I really don’t mind it, as my high-capacity banks make me pretty much energy independent on e.g. longer camping trips without access to a wall outlet.

In addition to the batteries, there are also other factors that influence the weight of your power bank.

The most significant of which is undoubtedly the power bank’s casing, which can be made of either silicone, hard plastic, or aluminum alloy. Power banks built for durability generally use harder, tougher materials, which naturally will also weigh more.

Lithium-Ion vs. Lithium Polymer Batteries

The energy density of the lithium-ion battery is twice that of regular nickel-cadmium batteries. This makes it a popular choice among batteries for high energy density. It is known for its reputation as a low-maintenance battery.

But a lithium-ion battery is fairly fragile. It requires a protection circuit for safer working. The protection circuit can cap the peak voltage, preventing it from dropping too low while the discharging occurs. Other significant issues include capacity deterioration and aging.

Lithium-polymer batteries, on the other hand, have a very low profile and are very lightweight. They are considered safer and more resistant to overcharging.

This means that there is a much lower chance of electrolyte leakage. Lithium-polymer batteries do not require heavy casing either, making them the far lighter alternative of the two battery types.

However, lithium-polymer batteries have a far higher cost-to-energy ratio than lithium-ion batteries, which is why most manufacturers won’t use them.

But don’t worry! As the power bank market is now rapidly expanding and developing, I am sure that other battery alternatives that are both lighter and more cost- and energy-efficient will be found in the near future!

Is a Power Bank Heavier When Charged?

The mass of a battery does change when it is charged. With the discharge cycle, the mass of the power bank decreases. This holds true for most battery types and has everything to do with Einstein’s relativity theory E=mc2.

However, the change of mass between discharged and fully charged battery is pretty much negligible and cannot be measured by conventional scales. Hence, it doesn’t really play a significant role when it comes to the overall weight of the power bank.

Therefore, for all practical purposes, you can assume that almost no mass is gained or lost in the process and that the power bank’s weight as stated by the manufacturer is pretty much on-point!

What Are the Lightest Power Banks on the Market?

Below I’ve listed some of the market’s lightest top-quality power banks that still manage to have a decent charging capacity. All of these models can be purchased on Amazon for a very decent price:

Anker PowerCore 10000mAh

This lithium-ion battery power bank weighs a mere 181.4 g and has a 2A input and 5V output. It is almost 20% lighter than other power banks with the same capacity. It’s a very popular model that millions of people use and are satisfied with.

Anker is known for its PowerIQ and VoltageBoost Features, which make the PowerCore 10000 a top-notch and lightweight pick!

Asus ZenPower 10050mAh

The Asus ZenPower 10050 weighs 215 grams. It is less than an inch thick and has a super-lightweight anodized aluminum casing. The ergonomic design and slim feel make it a very popular choice. It also offers pass-through charging and has an inbuilt PowerSafe Technology.

RAVPower 22000mAh Power Bank

For those of you looking for a light power bank with a higher capacity, the RAVPower 22000 packs a punch. It weighs a mere 412 grams, which is really light for a power bank with a capacity of more than 20.000mAh!

This power bank is one of those that pack a lithium-polymer battery instead of a lithium-ion, which mostly explains the weight superiority. Its battery is very efficient, safe, and has an outstanding charging performance.

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