Why Do Cordless Vacuums Use a Lithium-Ion Battery?

Lithium-ion batteries have become increasingly common in consumer electronics. Many of the vacuums on our list of the best cordless vacuums come with a lithium-ion battery, and manufacturers often boast that their models include this battery type.

But what makes a lithium-ion battery different to other types? How do they work? And what are the advantages? Keep reading to find out.

What is a Lithium-Ion Battery?

Without getting too technical, a Li-ion battery is a rechargeable battery that, unlike other types, uses lithium ions. These ions move between electrodes in one direction to recharge and another to discharge.

A lithium-ion battery is made up of several components. The most important include a monitor for assessing battery charge, a temperature sensor to track temperature changes, a voltage converter and a voltage tap.

The batteries can be found in a variety of shapes and sizes, from large laptop batteries to those that fit into your phone. Inside, however, they all use the same process for storing and discharging energy.

How Do They Work?

The interior of a Li-ion battery is pressurised. This is vital for the chemical reaction, but also adds an element of risk.

For this reason, the exterior of a lithium-ion battery is usually made from metal. In most cases, the casing has a pressure vent. If the pressure inside the battery increases too much, the vent allows it to normalise and prevent explosion – although the battery is likely to be damaged beyond repair by this point.

While a Li-ion battery might look simple from the outside, there’s a lot going on behind the scenes. The basic structure of the battery is combination of three thin sheets of material – a positive and negative electrode and a third sheet to act as a separator.

When charging, ions move between the electrodes. Then on discharge they move in the opposite direction. This flow of ions is the basic mechanism for storing and discharging energy.

An interesting note about the Li-ion battery is that the charge state monitor is actually a small computer. This is one of the reasons why a lithium-ion battery is more expensive. The purpose of the computer is to track the amount of charge, so that it can provide information to the appliance. It may also regulate temperature by preventing energy flow if the battery gets too hot.

What are the Advantages for Cordless Vacuums?

One of the biggest downsides to early cordless vacuums was battery life. Even today, one of the reasons people are reluctant to switch to a cordless is the limited run-time between charges (along with reduced suction).

For this reason, improving battery life has been a primary concern amongst vacuum manufacturers.

The good news is that battery technology, in general, has greatly improved on cordless vacuums since the first models. They are now more efficient, allowing for greater power without compromising battery life. This is partly because lithium-ion batteries are now included in most of the best models.

There are a number of advantages to lithium-ion batteries compared to other types. These include:

• They can hold charge much more efficiently than other types of battery. For comparison, a lithium-ion battery only loses around 5% charge per month (mainly due to the on-board computer), whereas other popular batteries can lose up to 20%.
• They weigh less than other batteries of a similar size. This allows vacuum manufacturers to pack greater energy into a smaller battery.
• Unlike some other types of battery, you do not need to fully discharge them to prevent the batteries run-time decreasing. This is vital for cordless vacuums, as you won’t always want to completely drain the battery before recharging.
• They can be charged and drained more times than other types of battery.

There are some drawbacks to lithium-ion batteries though, including that they only last two or three years after manufacture, they are more sensitive to heat and are also more expensive.

Which Cordless Vacuum Have a Lithium-Ion Battery?

Increasing numbers of cordless vacuums come with a lithium-ion battery, mainly because they hold their charge more efficiently. Some of the most popular models include:

• Bosch BCH625KTGB Athlet – this model was once one of our favourite cordless vacuums. The 60 minute run-time is the longest we’d seen at the time of the review and it provides decent suction power.
• Gtech AirRam – this is another of our favourites. It’s built with a lithium-ion battery for increased run-time.
• Morphy Richards 732004 – this slimline budget vacuum includes a an 18V Li-ion battery.
• Dyson V6 Absolute – the strong suction power of the V6 requires a Li-ion battery.

A notable exception is the Dyson V8 range, which is our top-rated cordless vacuum cleaner. For this range, Dyson have chosen a Nickel-Cobalt-Aluminium battery. We’ll do an article on this type of battery in the near future.

Summary

Lithium-ion batteries have a number of advantages over other types of battery, which is why they’ve become increasingly common in cordless vacuums. These advantages include better charge retention, ability to complete more charge cycles and a lighter weight.

They have their drawbacks though, such as the relatively short lifetime and heat sensitivity. They certainly aren’t the “perfect” battery as some manufacturers would like you to believe. Even so, many of our favourite cordless models use Li-ion batteries for the advantages they provide.