Running out of power for your cordless power tools on a job site or away from a standard power outlet can be a real inconvenience. While it’s not always ideal, charging your power tool batteries in your car can be a viable solution in certain situations. This guide explores a practical approach to charging your batteries using your vehicle’s power.
One straightforward method to achieve this is by utilizing a cigarette lighter inverter, also known as a power inverter. These devices convert your car’s 12V DC power from the cigarette lighter or accessory outlet into standard AC power, which is what most power tool battery chargers require.
To demonstrate this, consider a real-world scenario. Imagine you have a power inverter, like a 400-watt AC Delco inverter, plugged into the accessory outlet of your vehicle. After starting your car to ensure sufficient battery charge, you can then plug your power tool battery charger into the inverter.
Let’s take the example of charging Milwaukee M18 batteries. In a test, a basic Milwaukee multi charger with a 2.1 AC amp draw was connected to the inverter. A 2.0AH M18 battery, initially at a 2-bar charge level, was brought up to a full charge (green light indicator) in approximately 15 minutes. Following this, a larger 5.0AH M18 battery, starting at just one bar, was charged for 75 minutes until it reached a 4-bar charge and a green light indication. This resulted in a total charging time of 90 minutes for both batteries.
After charging and disconnecting the equipment, it’s worth noting that the car battery voltage can rebound slightly, indicating that the charging process, in this instance, did not excessively drain the vehicle’s battery. The vehicle subsequently started without issue, suggesting that for moderate charging needs, this method can be effective.
It’s important to remember that while this method can work, it’s generally more efficient to have enough batteries on hand to avoid needing to charge from your car. However, in situations where you are caught short, using a power inverter to charge your power tool batteries in your car offers a practical and accessible solution. Always ensure your inverter is adequately rated for the power draw of your battery charger and monitor your car battery’s condition, especially during extended charging sessions.
