It’s convenient to keep your power tools in your car, especially if you’re a professional or frequently move between job sites. But when it comes to battery-powered tools, a crucial question arises: Is It Safe To Leave Power Tools In Your Car? This is particularly important to consider with the increasing reliance on lithium-ion batteries in cordless power tools. Let’s delve into the safety aspects of storing your valuable power tools in your vehicle.
Understanding Temperature and Power Tool Batteries
One primary concern when storing power tools in your car is temperature. Cars can experience extreme temperature fluctuations, becoming ovens in the summer and freezers in the winter. While it’s true that power tool batteries, particularly lithium-ion types, are designed to withstand a range of temperatures, extreme heat is more of a concern for the longevity of the battery rather than immediate safety.
Reputable battery manufacturers rate their cells to operate safely up to around 70°C (158°F). Safety tests, like those conducted by Samsung, even involve heating cells to 130°C (266°F) for short periods to assess their resilience before thermal runaway occurs. Thermal runaway is a dangerous condition where the battery overheats and can potentially catch fire. However, for quality batteries from well-known brands, spontaneous thermal runaway due to temperature alone is rare. The risk is significantly higher with low-quality, off-brand batteries which may have manufacturing defects. This is a key reason why investing in trusted brands for your power tool batteries is advisable.
Best Practices for Storing Power Tool Batteries
To maximize safety and battery life, it’s recommended to remove batteries from your power tools and chargers when they are not in use. This practice addresses several potential issues. Firstly, some power tools and chargers, even when turned off or not actively charging, can have a standby drain. This drain, although small, can lead to a battery becoming deeply over-discharged over time. A deeply discharged lithium-ion battery can become a fire risk when recharged.
Secondly, leaving batteries on chargers indefinitely, even when the charger is plugged in but not actively charging, can also negatively impact battery longevity. While it’s generally not a direct safety hazard, constantly keeping a battery at 100% charge is not ideal for its lifespan.
For storage location, while a garage might seem like a natural choice, garages can also experience significant temperature swings. If your garage is uninsulated and gets excessively hot in the summer or very cold in the winter, consider storing your batteries in a more temperature-controlled environment, such as a utility closet inside your house. Regardless of location, it’s wise to store batteries away from easily flammable materials as a basic safety precaution. Having a smoke detector in the vicinity of your battery storage area adds an extra layer of safety.
Lithium-ion Battery Safety: Putting Risks in Perspective
It’s worth noting that lithium-ion batteries are ubiquitous in modern life, found in laptops, smartphones, and many other devices we use daily. The fundamental battery chemistry and inherent stability are similar across these applications. However, the risk does become somewhat cumulative. A power tool battery pack often contains multiple individual cells. If each cell has a small chance of a defect that could lead to a fire, the more cells you have, the slightly higher the overall risk becomes. This is why responsible handling and storage are important, especially if you own a large number of power tool batteries.
Research from the aviation industry provides valuable insights into lithium-ion battery safety. Studies have shown that the energy released by a lithium-ion battery in thermal runaway (fire) is related to its state of charge. Batteries with a lower state of charge present a significantly reduced fire risk. This is why regulations for air cargo shipments of lithium-ion batteries often require them to be charged to no more than 30%. Storing your power tool batteries at a lower state of charge, for example, around 50% or less, can be a simple yet effective safety measure. Furthermore, storing batteries at a lower charge level also contributes to improved long-term battery health and reduces aging.
In conclusion, while modern power tool batteries from reputable brands are designed with safety in mind, it’s wise to take sensible precautions. Leaving power tools in your car occasionally might not lead to immediate disaster, but prolonged exposure to extreme temperatures and improper storage practices can impact both battery safety and longevity. By removing batteries from tools and chargers, storing them in a temperature-stable environment, and ideally keeping them at a moderate state of charge, you can minimize any potential risks and ensure your power tools are ready and safe for use when you need them. For more detailed information on lithium-ion battery safety testing, you can refer to reports like this FAA study: https://www.fire.tc.faa.gov/pdf/tctn22-27.pdf.
