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Battery runtime: everything you need to know

Understanding battery runtime on cordless products

We’ve started to include battery runtime on some of our cordless products (all stated as an ‘up to…’ figure). However, it’s important to understand that there are a range of factors which can impact the runtime you get from your product during day-to-day use. The role of the battery is to power the motor that drives the product, regardless of what product type it is. As a result, there are some common things to consider when trying to understand what runtime you will get when using your product. We’ve grouped it into three areas; the conditions the products are used in, the product specifications, and battery care.

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Working conditions

The conditions the products are used in will have the biggest impact on the runtime you get from the battery.

Grass length

This is something worth considering if you haven't mown or trimmed your lawn for a while. Longer grass increases the demand on the motor driving your lawnmower blade or trimmer spool due to the greater resistance from the grass, reducing runtime. To combat this, for lawnmowers especially, we recommend cutting regularly using higher cutting heights earlier in the season and gradually lowering the height over subsequent cuts to your preferred height. This will also encourage lawn growth.

Overgrown/dense vegetation

Similarly to cutting longer grass, overgrown or areas with dense vegetation increase the demand on the product due to the volume of material that needs clearing. This will decrease the runtime of the battery. For very overgrown areas, we suggest using a 36V battery instead of an 18V as the greater power should make it easier to cut through the vegetation.

Wet or dry conditions

Although there is no danger to the battery if used in wet conditions, we strongly recommend using in as dry conditions as possible. The wetter the conditions the greater power needed to conduct the same work versus dry conditions, due to greater resistance from the vegetation being cut. This increases demands on the motor and lowers the runtime. This can be the case on wet grass when mowing or trimming your lawn, using a brushcutter to clear overgrown areas, damp wood when using a chainsaw or when clearing leaves using a blower/blow vacuum. We strongly recommend using in as dry conditions as possible to maximise runtime.

Garden terrain

There are benefits to using cordless mowers on uneven terrain, namely their relative lightness and better manoeuvrability versus petrol models. However, use on steep gradients can impact battery runtime due to the greater power needed to cut moving uphill, and regular adjustments needed to ensure an even cut.

Thicker branches

This is especially relevant for hedge trimmers and chainsaws. Thicker branches require more power to cut through and will reduce the runtime versus cutting through softer material.

Occasional usage

Your runtime will be maximised when you use a fully charged battery. If you do not use your product on a regular basis, it is easy to forget to charge the battery prior to beginning your task. This means your runtime is limited to how much charge is left in the battery from when you last used it. It is good practice to charge the battery after each use or have a charged spare ready to go.

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Product specifications

As the technology within cordless products improves, there are a few things to look out for which can impact battery runtime:

Brushless motors

Brushless motors are becoming increasingly common on garden power products, especially on more higher spec products. The advantage brushless motors have is they reduce friction within the motor, allowing the battery to run more efficiently and increasing runtime versus standard motor. However, they are typically more expensive versus standard products.

Battery temperature

The more a battery heats up, a reduction in runtime might be experienced due to the faster drain on the battery caused by higher temperatures. Some battery platforms (e.g. Erbauer EXT) feature technology designed to keep the battery cooler while in use, allowing for an increased runtime compared to a more standard battery.

Battery amp hour versus product

Runtime stated in our stores is based on the battery included with the product when sold. However, the interchangeable nature of battery systems means it is possible swap between batteries on products which are part of the same platform. Depending on the product and battery, this will impact the runtime you get. For example, the demands on the motor and battery when using a lawnmower means using a 2.0ah battery is not advisable as your runtime will be very limited versus a 5.0ah battery. Comparatively, trimmers/hedge trimmers are typically sold with 2.0/2.5ah batteries but will work with 4.0/5.0ah batteries on the same platform. While you should typically get a greater runtime using larger batteries, they will increase the weight of the product and can negatively impact its usability.

Product features

There are a number of features built into certain products which can impact the runtime you get. Some are designed specifically to increase the runtime whereas others will have a detrimental effect on runtime due to the power needed to ensure they work correctly (although may be potentially useful in terms of how the product is used).

A couple of examples:

  • Variable speeds/eco mode (leaf blowers in particular). Certain products have the ability to adjust the speed to suit the task you need. Running on lower speeds should increase the runtime of battery but it might take longer to complete your task. Whereas running on higher speeds means you can complete the same task quicker, you run the risk of losing battery life.
  • Self-propulsion (lawnmowers in particular). Self-propelled propulsion is a popular feature on lawnmowers and there are some battery powered models which have this functionality. However due to the increased power required to drive the wheels, using this sitting will reduce the runtime versus a standard hand-propelled model.

Battery care

Although low maintenance is a key advantage of cordless products, there a number of things you can do to ensure your battery is well looked after and your product runs efficiently. These should have a positive impact on the longevity of your battery and ultimately, its sustained runtime.

Preparing for charging

It is important to slightly warm a battery up before charging. Lithium-Ion batteries generate heat when in use, so it is advisable to give the tools some light use before charging the battery if possible.

Battery storage

When the tools are not in use put a battery in a warm place to prevent it getting too cold. Always remove the battery from the tool while in storage. Try to avoid leaving them in cold places as this could be detrimental to the battery. Make sure to bring them inside to keep them warm and safe, especially during winter. If possible, always store batteries with at least 50% charge. During summer months it is advisable to allow batteries to cool before charging as the hotter they are, the less storage capacity they have.

Battery cleanliness

Make sure to keep batteries clean and free from debris as this can cause problems when you come to use and charge them. Make sure to pay special attention to venting to allow for proper cooling.

Spare batteries

Lithium-Ion batteries do not have a “memory” so can be charged and discharged at any point and do not have to be fully charged before use. It is advisable to have at least two batteries and charge them in cycles i.e., use one battery while the other is charging, but remember you do not have to wait for a battery to fully charge before re-using if you have an urgent task to complete. It is worth understanding how long your battery should take to charge when making your purchase.

Product maintenance

It is important to clean your tools after each use to ensure that all moving parts have free movement without being impeded by debris or dirt. This will mean the battery power is being used most efficiently to deliver the ultimate performance and runtime.

Always keep blades or chains sharp, lubricated and as free from corrosion as possible. The sharper something is the less power it should take to perform the task therefore prolonging the battery run time and product performance.