A battery chainsaw lets you cut firewood, prune limbs and fell small trees without mixing fuel or pulling a starter cord. The Greenworks 40V chainsaw operator manual states that the tool is designed for cutting branches, trunks, logs and beams of a diameter determined by the cutting length of the guide bar, and it is only intended for cutting wood. The same description appears in the Greenworks 82V manual. Both manuals warn that the saw is not for professional tree services and must not be used by children or anyone without adequate personal protective equipment.
Key Parts and How a Battery Chainsaw Operates
A battery chainsaw uses a rechargeable battery pack to spin a motor that drives a toothed chain around a guide bar. The University of Hawaii CTAHR publication “Chain Saw Selection, Operation and Maintenance” describes the guide bar as the part that supports and provides a track for the saw chain, while the chain sprocket is the powered toothed wheel that drives the chain. The chain brake, which stops the chain if the hand guard is tripped, is a critical safety feature. The Greenworks 82V manual explains that you engage the chain brake by pushing the guard forward and disengage it by pulling the guard backward.
Both Greenworks manuals note that the chain must be lubricated with bar and chain oil. The oil tank on the 40V model holds 200 ml, and the 82V model holds 250 ml; in each case, a full tank lasts approximately 20 to 40 minutes of operation. The saw will not run correctly without sufficient oil, and the manuals caution against using dirty, used or contaminated oil because it can damage the bar or chain.
Choosing a Battery Chainsaw: Bar Length, Voltage and Safety Features
The University of Hawaii CTAHR advises that a chain saw should be picked for the main cutting jobs it is to do. Most nonprofessional users, the publication says, buy medium-sized saws with 14- to 20-inch bars and weighing 10 to 16 pounds. As examples, the Greenworks 40V model has a 14-inch guide bar, while the Greenworks 82V model has a 20-inch guide bar. The voltage of the battery pack (40V or 82V in these examples) is a model-specific figure, not a general rule for all saws. When you choose a battery chainsaw, also consider whether you already own other tools on the same battery platform; our guide on choosing a battery platform for yard tools can help you think through that decision.
Safety features matter as much as cutting capacity. UF/IFAS Gardening Solutions recommends looking for a low-kickback chain, a hand guard and a chain brake when you purchase a chain saw. The Greenworks manuals describe the chain brake and the lock-out button that must be pressed together with the trigger to start the saw, which helps prevent accidental starts. For a closer look at bar and chain specifications, see our chainsaw bar and chain guide.
Safety Gear and Personal Protective Equipment
The Canadian Centre for Occupational Health and Safety (CCOHS) recommends specific personal protective equipment when operating a chainsaw. Eye protection should include safety glasses with side shields, safety goggles or a face shield approved by standards such as CAN/CSA Z94.3-20. A face shield alone, without safety glasses, does not provide adequate eye protection. For hearing protection, CCOHS notes that chain saws create high noise levels of up to 95 to 115 dBA, so devices approved by standards like CSA Z94.2-14 are needed.
CCOHS also advises leather gloves with ballistic nylon reinforcement on the back, which offer a good grip and can prevent cuts when sharpening the saw. Foot protection should be heavy, well-fitted safety boots made from cut-resistant materials; boots made of ballistic nylon offer the best cut protection. Leg protection means trousers or chaps with sewn-in ballistic nylon pads, and clothing should be close-fitting without cuffs to prevent entanglement. A hard hat approved by CSA Z94.1-15 is recommended. The Greenworks 40V manual adds that further protective equipment for head, hands, legs and feet is recommended, and adequate protective clothing will reduce personal injury from flying debris or accidental contact with the saw chain. Our article on chainsaw protective gear covers this topic in more detail.
How to Use a Battery Chainsaw Safely
Both Greenworks manuals instruct the operator to hold the chainsaw with the right hand on the rear handle and the left hand on the front handle, with thumbs and fingers encircling the handles. The 40V manual states that holding the saw with a reversed hand configuration increases the risk of personal injury and should never be done. Before starting, make sure the saw chain is not in contact with anything. To start the saw, press the lock-out button and the trigger at the same time; releasing the trigger stops the motor.
Kickback is a sudden reverse reaction that can occur when the nose or tip of the guide bar touches an object, or when the wood closes in and pinches the saw chain in the cut. The Greenworks manuals explain that kickback forces can be controlled by maintaining a firm grip with both hands, not overreaching, and not cutting above shoulder height. The University of Hawaii CTAHR adds that a slow-moving chain is more likely to grab and cause kickback than one cutting freely at higher speed, so keep the engine speed up during cuts.
When felling a tree, the Greenworks manuals describe making a lower-level notching cut that is one-third the diameter of the tree and perpendicular to the felling direction, followed by a felling cut no less than 2 inches above the notching cut. For limbing, remove small limbs in one cut and keep larger lower branches as support until the log is limbed. When bucking a log into lengths, stand on the uphill side, control the saw completely and release cutting pressure near the end of the cut. The University of Hawaii CTAHR emphasizes working from the ground, not the log, and avoiding operating a saw above waist level.
Chain Lubrication, Tension and Maintenance
Both Greenworks manuals state that you should examine the chain oil level before each use and add bar and chain oil if necessary. The oil indicator on the saw lets you check the level without opening the tank. The manuals warn not to use the machine without sufficient chain oil, as this can damage the bar or chain.
Chain tension must be checked regularly because a chain stretches with use. The Greenworks 40V manual says to tension the chain so that it can only just be pulled away from the bar at its centre point. During normal operation, the temperature of the chain increases, and the drive links of a correctly tensioned warm chain will hang approximately 1/16 inch (1.58 mm) out of the bar groove. A slack chain may jump off and cause serious or even fatal injury. The University of Hawaii CTAHR recommends checking chain tension frequently: while lifting the nose of the guide bar, pull the chain away from the top of the bar and release it; the chain is properly tensioned if it does not sag and can be moved freely along the guide bar by a gloved hand.
Sharpen the cutters when the chain does not go into wood easily. The Greenworks manuals specify using a 5/32 inch (4 mm) diameter round file for the cutters’ corners and a flat file for the top plate, side plate and depth gauge. File all cutters to the same length and keep the file flat with the surface. The University of Hawaii CTAHR notes that signs of a dull chain include fine sawdust instead of chips, chain chatter, an overheated bar, curved cuts and the operator having to apply too much force. Replace the chain if the cutting edges are less than 1/5 inch (5 mm) long or if there is too much space between the drive links and the rivets. For guide bar maintenance, both Greenworks manuals advise lubricating the nose sprocket bearings, cleaning the bar groove with a scraping hook, cleaning the lubrication holes and removing burr from the edges with a flat file. Our chainsaw maintenance guide walks through these steps in detail.
Key Checks and Why They Matter
| Feature or check | Why it matters |
|---|---|
| Chain tension | A slack chain can jump off the bar and cause serious injury (Greenworks 40V manual). |
| Chain oil level | Running the saw without sufficient oil can damage the bar or chain (Greenworks 40V manual). |
| Chain brake function | The chain brake stops the chain if the hand guard is tripped, reducing injury risk (University of Hawaii CTAHR). |
| Guide bar condition | A worn bar can make the chain lean to one side; replace the bar if the groove does not fit the drive links (Greenworks 82V manual). |
| Sharp chain | A dull chain produces fine sawdust, overheats the bar and forces the operator to push harder (University of Hawaii CTAHR). |
| Battery charge | A low battery may cause the motor to stop or cut poorly; charge the battery pack before use (Greenworks 40V troubleshooting). |
| Personal protective equipment | Eye, hearing, hand, foot and leg protection reduce injury from flying debris or accidental chain contact (CCOHS). |
Frequently asked questions
How often should I check the chain tension?
The Greenworks 40V manual says to examine the chain tension before each use. Because a chain stretches as it heats up during cutting, the manual also advises adjusting the chain regularly to take up the slack. The University of Hawaii CTAHR recommends checking tension frequently and rechecking after making a few cuts.
What type of oil should I use in a battery chainsaw?
Both Greenworks manuals specify using bar and chain oil that is only for chains and chain oilers. They warn against using dirty, used or contaminated oil, which can damage the bar or chain. The oil tank should be filled before each use and monitored through the oil indicator.
Can a battery chainsaw fell a large tree?
The Greenworks manuals describe felling procedures and state that the saw is designed for cutting wood of a diameter determined by the cutting length of the guide bar. The University of Hawaii CTAHR notes that most nonprofessional users choose saws with 14- to 20-inch bars. A battery chainsaw can fell a tree whose diameter is within the capacity of its bar length, but the operator must follow the felling instructions and safety precautions in the manual.
For more on chainsaws and pole saws, visit our Chainsaws & Pole Saws page.
