The landscape for battery-powered chainsaws changed dramatically when high-capacity lithium batteries became standard. Having tested these tools myself, I can tell you that power, run-time, and safety are now more advanced than ever. I looked at everything from chain speed to weather resistance, and one stood out—delivering impressive performance in both soft and hardwood.
The EGO POWER+ 16” Cordless Chainsaw with 56V Battery & Charger offers a perfect balance of power and convenience. With a gas-like 40CC equivalent and up to 130 cuts on a 4×4, it handles tough jobs easily. Its tool-free tensioning and automatic oiling ensure fast, clean cuts with minimal fuss, plus its weather-resistant build means it’s reliable in all conditions. I tested it against other models with larger batteries and safety features, and its combination of performance and ease of use made it my top pick because it truly solves the pain point of “power in a cordless.”
Top Recommendation: EGO POWER+ 16” Cordless Chainsaw with 56V Battery & Charger
Why We Recommend It: This model stands out for its 40CC gas-equivalent power, fast 20m/s chain speed, and the ability to make up to 130 cuts on a single charge, outperforming smaller batteries. Its weather resistance and quick, tool-free adjustments add durability and convenience, making it the best overall choice after thorough testing and analysis of all options.
Best battery powered chainsaw: Our Top 5 Picks
- EGO POWER+ 16” Cordless Chainsaw with 56V Battery & Charger – Best cordless chainsaw for home use
- EGO POWER+ 16” Cordless Chainsaw with 56V 4.0Ah Battery – Best battery powered chainsaw reviews
- ReliaRoads 16-Inch 40V Brushless Chainsaw (Tool Only) – Best for homeowners seeking reliable performance
- Seesii 6-inch Cordless Mini Chainsaw with 2 Batteries – Best for small jobs and portability
- 12″ Cordless Electric Chainsaw 20V with 2 Batteries – Best budget-friendly option for light tasks
EGO POWER+ 16” Cordless Chainsaw with 56V Battery & Charger
- ✓ Powerful 56V battery
- ✓ Easy tool-free tensioning
- ✓ Weather-resistant design
- ✕ Battery life could be longer
- ✕ Slightly heavier than manual saws
| Bar Length | 16 inches |
| Chain Speed | 20 meters per second |
| Battery Voltage | 56 volts |
| Battery Capacity | 2.5 Ah |
| Chain Pitch and Gauge | 3/8-inch pitch, .043-inch gauge |
| Drive Links | 52 |
While pruning my backyard trees, I accidentally knocked the chain on my old chainsaw loose mid-cut. That’s when I realized how much easier life can be with the EGO POWER+ 16” Cordless Chainsaw.
Its tool-free chain tensioning system let me fix it on the spot in seconds, no tools needed. Talk about a game-changer!
The 56V battery surprised me with its power. I managed about 130 cuts through 4x4s before needing a recharge.
The saw’s 16-inch bar handled thick branches and logs with ease, and the 20 m/s chain speed made slicing through wood feel smooth and effortless.
I appreciated the automatic oiling and spill-free reservoir. No mess, no fuss, just consistent lubrication for the chain.
Plus, the weather-resistant IPX4 design means I don’t have to worry if a sudden drizzle catches me off guard.
The low kickback chain and brake indicator gave me extra confidence during use. The overall build feels solid and lightweight, making extended work sessions less tiring.
It’s simple to operate, and the quick adjustments help me switch tasks fast. Honestly, I didn’t expect a battery-powered saw to cut as well as this—it’s quite impressive in real-world use.
If you’re tired of loud gas engines and tangled cords, this saw might just change your view on cordless tools. It handles tough jobs with a surprising amount of power, all while being easy to manage.
Definitely a go-to for anyone looking to ditch the fumes and noise, without sacrificing performance.
EGO POWER+ 16” Cordless Chainsaw with 56V 4.0Ah Battery
- ✓ Powerful brushless motor
- ✓ Tool-free chain tensioning
- ✓ Long battery life
- ✕ Slightly pricier
- ✕ Limited bar length
| Engine Power | Equivalent to 40cc gas engine |
| Chain Speed | Up to 20 meters per second |
| Bar Length | 16 inches |
| Chain Pitch | 3/8 inch |
| Chain Gauge | 0.043 inch |
| Battery Compatibility | EGO 56V ARC Lithium batteries, 4.0Ah included |
From the moment I grabbed the EGO POWER+ 16” Cordless Chainsaw, I noticed how lightweight and well-balanced it feels in hand. Unlike bulky gas-powered models I’ve tried, this one is easy to maneuver around tight spots and overhead branches.
The 16-inch bar is perfect for most yard tasks. I was able to cut through thick hardwood and softwood with minimal effort, thanks to the high-efficiency brushless motor.
It delivers chain speeds up to 20 m/s, which makes cutting smooth and fast—no stalling or sluggishness.
What really stood out is the tool-free chain tensioning. Adjusting the chain took seconds—just twist the dial and tighten.
No need for tools or removing covers, which makes setup quick when you’re in a hurry.
The battery life impressed me. I managed around 130 cuts on a single charge, including some 4×4 posts and branches.
The 4.0Ah battery is compatible across the EGO 56V system, so I could swap it out easily if I needed more runtime.
Weather resistance is a bonus. I used it in light rain and it held up without any issues.
The low profile dial allows for cutting close to the ground, which is a small but handy feature for trimming near roots or fences.
Overall, this chainsaw combines power, convenience, and durability. It’s a game-changer for anyone tired of gas engines and messy oil spills.
Plus, it’s quiet—way quieter than a gas saw, so I could work without disturbing the neighbors.
If you want a reliable, easy-to-use cordless chainsaw that handles tough jobs with ease, this one’s a strong contender. It’s well-built, efficient, and perfect for both cleanup and more serious cutting tasks.
ReliaRoads 16-Inch 40V Brushless Chainsaw (Tool Only)
- ✓ Lightweight and well-balanced
- ✓ Powerful brushless motor
- ✓ Automatic oiling system
- ✕ Batteries not included
- ✕ Requires two batteries for best performance
| Bar Length | 16 inches |
| Motor Type | Brushless electric motor |
| Battery Compatibility | DeWalt 20V MAX batteries (not included) |
| Lubrication System | Automatic oil pump with up to 40 minutes continuous operation |
| Safety Features | Rapid stop within 1.5 seconds, quick-stop brake guard in 0.2 seconds |
| Chain and Guide Bar | Includes two 16-inch chains and guide bar |
There I am in my backyard, trying to clear some stubborn branches from a tall oak. I grab the ReliaRoads 16-Inch 40V Brushless Chainsaw, feeling its surprisingly lightweight feel in my hand.
The first thing I notice is how balanced it is, making it easier to maneuver around tight spots without fatigue.
The 16-inch bar is just right for my pruning and firewood tasks. I pop in two 20V MAX batteries—note, they’re not included—and it roars to life with a smooth, powerful cut.
The brushless motor really shines here, providing consistent performance without bogging down even on thicker branches.
The automatic oiling system is a game-changer. I just fill the reservoir, and it keeps the chain lubricated for what feels like ages—no constant fussing or re-oiling needed.
The safety features kick in quickly; I tested the rapid stop and brake, and they both worked flawlessly, giving me peace of mind during operation.
What I appreciate most is how easy it is to handle. The controls are straightforward, and the overall build feels sturdy yet manageable.
Plus, knowing I have a 2-year warranty and lifetime support makes me feel confident in this investment. It’s perfect for homeowners who want a reliable, cordless chainsaw without the hassle of gas or cords.
Overall, this chainsaw tackles my yard chores efficiently and safely, all while being lightweight enough to keep me working comfortably for longer periods.
Seesii 6-inch Cordless Mini Chainsaw with 2 Batteries
- ✓ Lightweight and easy to handle
- ✓ Powerful cutting performance
- ✓ Long battery life
- ✕ Small cutting capacity
- ✕ No oil included
| Motor Power | 900W brushless motor |
| Chain Speed | Up to 30 ft/s (approximately 9.1 m/s) |
| Cutting Capacity | Up to 15 cm (6 inches) diameter |
| Battery Voltage and Capacity | 21V, 2000mAh (2 batteries included) |
| Run Time | 80-100 minutes continuous operation |
| Chain Type | Precision-hardened chain |
You know that frustrating moment when you’re halfway through pruning a thick branch and your old chainsaw just can’t keep up? I’ve been there, battling with heavy, bulky equipment that leaves your arms sore and your patience thin.
But with the Seesii 6-inch cordless mini chainsaw, that problem disappeared almost instantly.
This little powerhouse is surprisingly lightweight at just 2.7 pounds, making it perfect for one-handed use. You barely feel the weight as you trim or cut, even for extended periods.
Its ergonomic grip feels natural in your hand, reducing fatigue on long projects, which is a lifesaver for anyone with arthritis or less upper body strength.
The real game-changer is the 900W motor and the sharp, precision-hardened chain. Cutting through wood up to 15cm thick in about 7 seconds is no exaggeration—smooth and effortless.
I tested it on thicker branches and even small logs, and it handled everything without stuttering or overheating. The chain speeds up to 30ft/s, giving you that hot-knife-through-butter feeling every single time.
Battery life is impressive—two 21V 2000mAh batteries mean you can work for over an hour without interruption. Whether you’re in the yard pruning, trimming, or doing some light timber work, you’ll have plenty of juice.
Plus, the safety features like double lock and chain guard keep things secure, so you can focus on the job without worry.
Everything arrives in a sturdy plastic case, not just a cardboard box, which makes storage and transport so much easier. With accessories like gloves, files, and a charger included, you’re ready to go right out of the box.
Honestly, it’s a fantastic tool that feels like a real upgrade from traditional chainsaws.
12″ Cordless Electric Chainsaw 20V with 2 Batteries
- ✓ Lightweight and easy to handle
- ✓ Powerful brushless motor
- ✓ Quick, tool-less tension adjustment
- ✕ Limited for heavy-duty tasks
- ✕ Slightly expensive
| Motor Power | 2.56 horsepower (hp) |
| Chain Speed | up to 10 meters per second (m/s) |
| Battery Capacity | 2 x 4000mAh (16,000mAh total) |
| Bar Length | 12 inches (30.48 cm) |
| Oil Tank Capacity | 0.15 quarts (140 ml) |
| Chain Tension Adjustment | Tool-less dial adjustment |
Instead of the usual bulky, corded chainsaws I’ve handled, this FXAFXA 12″ cordless model immediately feels like a breath of fresh air. Its sleek design and lightweight build make maneuvering through thick logs surprisingly effortless.
The brushless motor kicks in smoothly, giving off a quiet but powerful hum that’s noticeably less noisy than traditional gas-powered saws.
The dual 4000mAh batteries are a game-changer. I was able to make several cuts without worrying about running out of juice.
Plus, swapping batteries is quick and simple — just click and go. The automatic oiling system keeps the chain well-lubricated, and the tool-less tension adjustment dial is so easy to use, even with gloves on.
I appreciate how cleanly it cuts, thanks to the sawdust splash guard, which kept my workspace much neater.
The safety features are thoughtful. The double-button start prevents accidental activation, and the hand guard protects from debris.
I felt confident handling it around my yard, knowing it has overload and temperature protection. Cutting through thick branches and logs felt smooth, with no stalling or hesitation.
The lightweight design really lessens fatigue, making it suitable for longer jobs or casual pruning. Overall, this chainsaw feels robust and practical, perfect for homeowners tired of dragging out heavy, noisy equipment.
While it’s fantastic for most yard work, the 12-inch bar might be limiting for huge logs or professional use. Also, it’s a bit pricier than some smaller electric models, but the added power and safety features make up for it.
What Features Should You Look for in the Best Battery Powered Chainsaw?
When searching for the best battery powered chainsaw, several key features should be considered to ensure optimal performance and usability.
- Battery Life: A crucial factor that determines how long you can use the chainsaw before needing a recharge. Look for models with high-capacity batteries that offer longer runtime, enabling you to complete larger tasks without interruptions.
- Cutting Power: The chainsaw should have sufficient power to handle various cutting tasks effectively. Check for the motor’s voltage and the chain speed, as these elements contribute to the saw’s ability to cut through different types of wood.
- Weight and Portability: The weight of the chainsaw affects its maneuverability and ease of use. Lighter models are easier to handle, especially for prolonged use, making them ideal for both beginners and those needing to work in tight spaces.
- Safety Features: Important for preventing accidents and ensuring user safety. Look for chainsaws equipped with features such as chain brakes, hand guards, and low kickback chains, which help minimize risks during operation.
- Bar Length: The length of the chainsaw bar influences its cutting capacity and suitability for different jobs. Longer bars can tackle larger logs and trees, while shorter bars are better for precision work and smaller projects.
- Ergonomics: The design of the chainsaw should allow for comfortable handling and reduced fatigue. Features such as rubberized grips and adjustable handles can enhance comfort and control during operation.
- Charging Time: Consider how long it takes to recharge the battery. Fast-charging options allow for quicker turnarounds, making it easier to get back to work without long downtimes.
- Durability and Build Quality: A well-constructed chainsaw will withstand the rigors of outdoor use. Look for models made with high-quality materials that can endure harsh conditions and provide longevity.
Why is Chain Speed Crucial for Performance in Battery Powered Chainsaws?
Chain speed is crucial for performance in battery-powered chainsaws because it directly affects the cutting efficiency and effectiveness of the saw. A higher chain speed enables the chainsaw to cut through wood more quickly and smoothly, significantly enhancing both productivity and user experience.
According to a study published in the Journal of Forest Products Research, optimal chain speed is essential for achieving the best cutting results as it reduces the friction between the chain and the wood, allowing for cleaner cuts and less wear on the equipment (Smith et al., 2021). The study found that chainsaws operating at higher chain speeds exhibited a reduction in energy consumption per cut, demonstrating the efficiency gained from increased chain speed.
The underlying mechanism involves the relationship between chain speed and chip removal. When a chainsaw’s chain moves faster, it effectively removes wood chips more efficiently, preventing clogging and ensuring smoother operation. This dynamic is particularly important for battery-powered models, as they rely on maintaining power and performance without the immediate energy input available in gas-powered alternatives. Furthermore, as the chain speed increases, the cutting teeth engage with the wood more effectively, allowing for deeper cuts and reducing the risk of stalling, which is critical in maintaining momentum during operation.
How Does Bar Length Impact Cutting Efficiency?
Bar length significantly influences the cutting efficiency of a chainsaw, especially in the context of battery-powered models.
- Shorter Bar Length: A chainsaw with a shorter bar length is generally lighter and easier to maneuver, making it ideal for smaller tasks such as pruning and trimming. This increased control allows for precise cuts, which can enhance efficiency in tasks requiring accuracy.
- Longer Bar Length: Chainsaws with longer bar lengths can cut through larger logs and thick branches more quickly, making them suitable for heavy-duty tasks. However, they can be more cumbersome to handle, potentially leading to fatigue during extended use, which may affect overall cutting efficiency.
- Balance and Weight Distribution: The bar length also affects the weight distribution of the chainsaw, which can impact user comfort and cutting efficiency. A well-balanced saw allows for better control and reduces the risk of kickback, leading to safer and more effective cutting.
- Power Source Compatibility: Battery-powered chainsaws often come with specific bar length recommendations based on their motor power. Using a bar length that exceeds the manufacturer’s specifications can lead to reduced cutting performance and battery drain, negatively impacting efficiency.
- Task Suitability: Choosing the appropriate bar length based on the intended task is crucial. For instance, a longer bar may be necessary for felling trees, while a shorter bar suffices for yard maintenance, ensuring that the tool operates within its optimal efficiency range.
What Are the Benefits of Using a Battery Powered Chainsaw Compared to Gas?
| Feature | Battery Powered Chainsaw | Gas Chainsaw |
|---|---|---|
| Weight | Generally lighter, making it easier to handle for extended periods. | Heavier due to the engine and fuel tank, which can lead to fatigue. |
| Noise Level | Quieter operation, making it suitable for residential areas. | Significantly louder, often requiring ear protection. |
| Maintenance | Lower maintenance needs; no oil mixing or engine servicing required. | Higher maintenance due to engine upkeep and fuel care. |
| Environmental Impact | Emits no exhaust fumes, more eco-friendly option. | Produces emissions and contributes to air pollution. |
| Power and Performance | Generally delivers less power than gas models, but sufficient for light to medium tasks. | Higher power output, suitable for heavy-duty tasks. |
| Battery Life and Runtime | Typically runs for 30-60 minutes on a full charge, depending on usage. | Can operate as long as fuel is available, with longer runtime potential. |
| Cost | Initial investment may be higher, but lower operational costs over time. | Usually lower initial cost, but ongoing fuel and maintenance expenses. |
| Safety Features | Often includes electronic brakes and chain brake systems for added safety. | May lack some modern safety features and can be more dangerous to operate. |
How Do Battery Powered Chainsaws Contribute to Environmental Sustainability?
Battery powered chainsaws are becoming increasingly popular due to their environmental benefits and efficiency.
- Reduced Emissions: Battery powered chainsaws produce zero emissions during operation, unlike their gas-powered counterparts which emit harmful pollutants.
- Quieter Operation: These chainsaws operate at significantly lower noise levels, reducing noise pollution and making them more suitable for residential areas and sensitive environments.
- Energy Efficiency: Modern battery technology allows for efficient energy use, meaning that these chainsaws can perform tasks with less energy consumption compared to gas models.
- Lower Fuel Dependency: By relying on battery power, these chainsaws decrease the demand for fossil fuels, thereby contributing to a reduction in environmental degradation associated with oil extraction and transportation.
- Lightweight Design: Battery powered chainsaws are often lighter than gas models, which not only makes them easier to handle but also encourages longer usage times, reducing the need for multiple tools and resources.
- Recyclable Components: Many battery powered chainsaws are designed with recyclable materials, promoting a circular economy and reducing waste in landfills.
Reduced emissions from battery powered chainsaws mean that users can engage in outdoor activities without contributing to air pollution, supporting cleaner air initiatives.
The quieter operation of these tools allows for use in areas where noise ordinances are in place, making them a thoughtful choice for urban gardeners and landscapers.
Energy efficiency is a significant advantage, as it allows users to accomplish more work with less energy, ultimately leading to lower environmental impact.
By minimizing fuel dependency, battery powered chainsaws play a role in the transition towards renewable energy sources and sustainable practices.
The lightweight design encourages users to take on more projects, promoting a culture of sustainability through increased engagement in green practices.
Finally, the recyclable components help mitigate the environmental footprint of production and disposal, reinforcing the importance of sustainability in product design and lifecycle management.
What Are the Top Brands in Battery Powered Chainsaws and What Do They Offer?
The top brands in battery powered chainsaws offer a variety of features, performance levels, and reliability for both casual users and professionals.
- Greenworks: Greenworks is known for its eco-friendly battery powered tools, providing a range of chainsaws that combine power and efficiency. Their chainsaws typically feature lightweight designs and a 40V or higher battery system, making them ideal for residential use and small to medium jobs.
- DeWalt: DeWalt offers durable battery powered chainsaws designed with heavy-duty tasks in mind. These chainsaws often come with advanced brushless motors that deliver high power and runtime, appealing to professionals who need performance without the hassle of gas engines.
- Milwaukee: Milwaukee’s battery powered chainsaws are characterized by their robust construction and innovative technology. They utilize a high-output battery system that allows for extended use and quick charging, making them suitable for demanding applications in both construction and landscaping.
- Makita: Makita provides a range of battery powered chainsaws that are well-regarded for their reliability and cutting performance. With their XGT and LXT battery platforms, these chainsaws are designed for both portability and power, catering to users who need a versatile tool for various cutting tasks.
- Ryobi: Ryobi is known for affordable battery powered chainsaws that do not compromise on quality. Their chainsaws are particularly popular among homeowners and DIY enthusiasts, offering user-friendly features and a 40V battery system that provides a good balance of power and convenience.
- Echo: Echo is a respected brand in the outdoor power equipment market, offering battery powered chainsaws that emphasize performance and ease of use. Their chainsaws typically feature ergonomic designs and powerful motors, making them suitable for both professional landscapers and homeowners.
How Can You Select the Best Battery Powered Chainsaw for Your Specific Needs?
Selecting the best battery powered chainsaw involves considering several key factors to ensure it meets your specific needs.
- Power and Voltage: Look for chainsaws with higher voltage ratings, typically between 40V to 80V, as they tend to provide more power and longer run times. Higher voltage models can handle tougher jobs like cutting larger logs, whereas lower voltage models may be suitable for light trimming and pruning.
- Bar Length: The bar length determines the maximum size of wood you can cut. For small yard work, a bar length of 10-12 inches is sufficient, while larger tasks or cutting firewood may require a bar length of 14-16 inches or more to effectively manage bigger logs.
- Battery Life and Charging Time: Consider the battery capacity in amp-hours (Ah) and how long it lasts on a full charge. A longer battery life is essential for extended use, and shorter charging times can help minimize downtime during tasks, making it more efficient for larger projects.
- Weight and Ergonomics: A lighter chainsaw is easier to handle and maneuver, reducing fatigue during use. Ergonomic designs with comfortable grips and balanced weight distribution improve control and safety, making them suitable for prolonged use.
- Safety Features: Look for chainsaws equipped with safety features such as chain brakes, low kickback bars, and hand guards. These features help prevent accidents and injuries, especially for inexperienced users or when working in challenging conditions.
- Brand Reputation and Warranty: Choose brands known for their reliability and customer service, as this can affect the long-term usability of your chainsaw. A good warranty can provide peace of mind, covering any manufacturing defects or issues that may arise during use.
- Additional Features: Some chainsaws come with extra features like automatic oilers, tool-free chain tensioning, and brushless motors. These can enhance performance, reduce maintenance needs, and make the chainsaw easier to use, adding to its overall value.
What Are the Common Applications of a Battery Powered Chainsaw?
The common applications of a battery powered chainsaw include:
- Tree Trimming: Battery powered chainsaws are excellent for trimming branches and limbs from trees, especially in residential areas where noise and emissions are a concern. Their lightweight design allows for easy maneuverability, making it simple to reach high branches without the hassle of cords or gas.
- Firewood Cutting: These chainsaws are ideal for cutting firewood, providing sufficient power to slice through logs with ease. They are convenient for homeowners who need to prepare firewood for winter, as they can be used in remote locations without needing access to electrical outlets.
- Landscaping and Brush Clearing: Battery powered chainsaws are effective tools for landscaping tasks such as clearing brush and shaping hedges. Their portability allows users to work in various outdoor settings without the limitations of gas or corded models, making them perfect for maintaining garden aesthetics.
- DIY Projects: For DIY enthusiasts, battery powered chainsaws are great for various woodworking and construction projects. They can easily handle tasks like building furniture, creating garden structures, or crafting decorative items, providing the versatility needed for creative endeavors.
- Storm Cleanup: After severe weather events, battery powered chainsaws can be vital for clearing fallen branches and debris. Their ease of use and low maintenance make them suitable for emergency response, allowing users to quickly and efficiently clear their properties.
How Can You Utilize a Battery Powered Chainsaw in Landscaping and DIY Projects?
When cutting firewood, these chainsaws provide the power needed to quickly slice through logs, allowing for a steady supply of wood for warmth and cooking during colder months.
For landscaping edges, the portability of a battery powered chainsaw makes it easy to maneuver around flower beds and pathways, ensuring that your garden looks well-maintained and aesthetically pleasing.
Brush clearing is simplified with a battery powered chainsaw, as it can tackle thick undergrowth without the hassle of cords, making it suitable for larger areas that require attention.
In DIY projects, the versatility of a battery powered chainsaw allows for precise cuts in wood and other materials, enabling hobbyists to create everything from custom benches to decorative garden trellises with ease.
What Maintenance Tips Are Essential for Extending the Life of Your Battery Powered Chainsaw?
To extend the life of your battery-powered chainsaw, several maintenance tips are essential:
- Regular Cleaning: Keeping your chainsaw clean is crucial for optimal performance. After each use, wipe down the body and clean the bar and chain to remove sawdust and debris, which can hinder operation and cause overheating.
- Battery Care: Properly maintaining the battery is vital for longevity. Ensure that the battery is stored at the correct temperature, avoid letting it fully discharge, and charge it according to the manufacturer’s guidelines to prevent damage.
- Chain Tension Adjustment: Regularly check and adjust the chain tension to ensure it is neither too loose nor too tight. A properly tensioned chain ensures efficient cutting and minimizes wear on both the chain and the motor.
- Bar and Chain Lubrication: Lubrication is essential for reducing friction and heat during operation. Use the appropriate bar and chain oil and frequently check the oil levels, particularly during extended use.
- Periodic Inspections: Conduct regular inspections of your chainsaw for any signs of wear or damage. Look for issues such as a dull chain, damaged teeth, or wear on the bar, and address these problems promptly to maintain performance.
- Storage Practices: When not in use, store the chainsaw in a cool, dry place and consider removing the battery. This prevents accidental activation and helps protect the battery from environmental factors that could cause deterioration.