Battery-Powered Chainsaws and Benefits to Worker Health

May 4, 2020 garry.mcgauran

In this article we discuss the occupational pros and cons of chainsaws powered by lithium-ion batteries.

We compare this battery-powered technology to traditional combustion powered models and highlight the health benefits. And we also reveal situations where battery powered chainsaws may not be a safer alternative to two-stroke models.

Name: Battery chainsaw. Electric cordless chainsaw.

Traditional technology: Combustion engine i.e. two-stroke petrol/gas driven chainsaws

Those at risk: Arborists. Forestry workers. Lumberers. Carpenters. Farmers. Firefighters. Landscapers. Gardeners. Groundskeepers. Utility workers. Maintenance operatives. Chainsaw artists.

we reveal situations where battery powered chainsaws may not be a safer alternative to two-stroke models

Risky business of chainsaws

When the objective of the day is to fell a large tree in a remote location and cut it into firewood sized pieces, the chainsaw is unrivalled. Since their introduction 40 years ago chainsaws became a game changer for those involved in forestry and other wood industries. The most rudimentary calculations showed that petrol chainsaws were between 5-10 times faster than the manual handsaws that they originally replaced. That is a lot of backbreaking labour saved. However it is no secret that chainsaws pose some serious health and safety hazards.

There is good reason why chainsaws are banned in workplaces where viable wood cutting alternatives exist. They are inherently unsafe and companies that are invested in chainsaws spend significant resources on operator training, safety education, and PPE. The following are quotes from Occupational Health & Safety regulatory bodies around the world:

Chainsaws have the potential to cause horrific injuries – HSE, UK

Chainsaws are one of the most dangerous power tools used during (hurricane) cleanup – OSHA, United States

While it makes light work of felling and cutting up trees, a chainsaw has the potential to inflict very serious injuries or create hazardous situations – SafeWork SA, Australia

Notable chainsaw hazards

The safety hazards associated with both battery powered and petrol powered chainsaws include:

Unprotected steel chain moving at high RPMs
Accelerated particles i.e. dusts and debris
Falling objects and materials i.e. tree-work
Kickback i.e. sudden uncontrolled upward and backward movement of the chain and guide bar towards the operator

The large forces at work, and the sharp moving chain associated with petrol chainsaws still exist with battery chainsaws. So why is this battery technology being adopted by companies around the world?

Battery chainsaw benefits

Battery chainsaws generate significantly lower decibel levels

Noise levels

The good news is that battery chainsaws can be used in urban environment such as school grounds, in ecologically sensitive areas, and indoors without breaching noise pollution bylaws. Petrol-powered chainsaws can run up to 119dB whereas battery models runs around 104 dB(A) and can be measured at the operators ear at 93dB (A). These noise reductions can have a significant cumulative effect for those operating saws in high-risk occupations.

Hand arm vibration

the reduction in exposure to hand arm vibration makes battery saws an attractive option for those serious about reducing occupational risks

Whilst most modern petrol driven chainsaws incorporate anti-vibration dampeners and heated handles, the risk of hand-arm vibration (HAV) still poses a health risk for regular users. Battery pack chainsaws generate significantly less vibration than gas powered saws. For e.g. Husqvarna models boast 2 m/s² from the front handle for cutting, and 2.4 m/s² at the rear handle for cutting. In comparison a similar petrol model produces vibration of up to 6.6 m/s² for cutting. In the UK for example any worker exposed above the 2.5 m/s² (over 8 hours) action level is entitled by law to health surveillance. In itself, the reduction in exposure to hand arm vibration makes battery saws an attractive option for those serious about reducing occupational risks.

Weight

The higher the cc of a petrol driven chainsaw the bigger the weight of the engine. At 5kg a chainsaw may seem light but the effects of fatigue will set in after 20-30 minutes no matter how fit or strong the operator is. At 2.4 kg (minus battery) a battery saw is nearly half as light as petrol models of the same size. Ergonomically this is a stark decrease in terms of physical loading, and can significantly reduce the risks of fatigue and injury.

Fumes and emissions

Electric powered chainsaws use clean technology and create almost no smoke or emissions. This means reduced physical exposure to petrochemicals and reduced inhalation of hydrocarbons. From an environmental perspective it also means zero harmful emissions being released into the atmosphere.

Harmful chemicals

The risk of fire and explosion always exists when using, storing, and transporting petroleum fuel and oil mix. Physical contact with fuels also carries the risk of dermatitis. Battery operated tools reduce the risk of exposure to chemicals and the sealed batteries present no chemical risk when handled. Most battery models are designed with automatic chain oilers which requires minimal exposure to these hazards.

Comparative risks

Combustion powered chainsaws are still unrivalled in heavy-duty use

Battery Power

The majority of battery chainsaws struggle for power when tackling larger tree trunks

Battery chainsaws come with a variety of bars and chains sizes, however they are not heavy duty saws and do not possess the torque of similar sized petrol models. The majority of battery chainsaws struggle for power when tackling larger tree trunks. They are not, designed for consistent heavy-duty use and have better applications in pruning, de limbing, DIY and in construction use. Large trees require quality petrol driven saws of 45cc engine or bigger. The largest sized battery powered chainsaws such as the Dewalt FLEXVOLT 60v and the impressive Greenworks PRO 80v are on a par with a 45cc petrol chainsaw. Without prior knowledge of voltage limitations there is scope for “wrong-tool-for-the-wrong-job” scenarios which lead to safety deviations and shortcuts.

The lithium-ion batteries that power cordless chainsaws are not without their own set of unique fire hazards. These batteries require careful management when handling and charging. Emerging Tech Safety discusses lithium battery safety in full detail here.

Battery longevity

The innovative technology at the centre of battery chainsaws is also one of its main weakness. Depending on the specific model and workload, an operator may get between 20-60 minutes from each battery. This type battery life limits portability, and unless the operator carries a backpack full of batteries he/she is not venturing too far away from a charging source. As a comparison, a petrol driven saw consumes less than a gallon of petrol over the course of a full working day. That said, technological advances will ensure that battery tools pack more power and capacity in the near future.

Cost

Battery powered chainsaws are expensive due to the manufacturing cost of lithium-ion batteries. Price is a barrier to uptake and no matter how much health and safety benefits a new technology presents, cost is the number one consideration for buyers. As with all new technology increased manufacturing efficiencies will ensure that battery chainsaws become less cost prohibitive.

Comment

We set out to examine the benefits and risks of battery operated chainsaws when compared to standard petrol driven models. The chainsaw is clearly an indispensable, labour-saving power tool used widely by arborists, farmers, and foresters. That said, chainsaws are a high risk piece of work equipment. They may lack the full power and longevity of petrol models however there are enough health gains – in noise, weight, vibration and chemical exposure – to make them a feasible alternative for tasks within their power capability. If chainsaws continue to be the main tool of choice in forestry and timber industries, it is crucial that employers strive to adopt innovative technology which lowers risk to the operator. Below are measures that organisations may take to manage risk around battery-operated chainsaws.

Actionable Information

Procurement: analysis of job and task requirements should dictate if and where battery-operated saws are applicable. Battery-operated chainsaws may compliment two-stroke models. For example, use of standard chainsaw to fell large trees and cut up trunk; and use of battery chainsaw to de-limb the tree and cut-up branches. Another example would be the exclusive use of battery-chainsaws in urban areas, or on school grounds. When procuring battery chainsaws ensure the power and battery longevity are suitable for the jobs and tasks at hand.

Risk assessment: before exposing workers to battery chainsaw risks organisations may want to risk assess: (i) Use and maintenance of the chainsaw; (ii) Use, storage and charging of Li-Po batteries; (iii) Each work process e.g. felling trees, de-limbing trees, and emergency chainsaw work.

Operating Procedures: develop standard operating procedures for regular work processes. Examples may include: felling trees, de-limbing trees, emergency chainsaw work and working near the public. Ensure that standardised chainsaw procedures are made available to all chainsaw users.

Instruction and training: provide necessary instruction and training to those working with, working around, and maintaining chainsaws.

PPE and safety equipment: provide suitable PPE for those operating chainsaws. These include: (i) Full face mask; (ii) Ear defenders; (iii) Gloves; (iv) Safety boots (v) Respiratory equipment.

For those in high risk industries organisations may want to consider (v) chainsaw pants, (vii) arborist helmets, and (viii) trouser suspenders to avoid loose or sagging clothing.

For those operating in public or emergency situations organisations may also want to incorporate (vii) modular guarding systems and (viii) fire extinguishers.

Note: Chainsaw safety is your responsibility. Always follow the chainsaw manufacturers directions. You should use the above information as general advice.

Emerging Tech Safety