How long can a 24V car fan last after the engine is turned off?
3 Answers
If you continue to use electricity after turning off the engine, it normally lasts about three to four hours. Below is relevant information: Car Battery: Since the battery uses lead-calcium alloy for the grid frame, the amount of water decomposition during charging is low, and the water evaporation rate is also minimal. Additionally, the sealed structure of the casing releases very little sulfuric acid gas. Compared to traditional batteries, it has advantages such as not requiring any liquid addition, easy connection to terminal posts, and long-term power storage. Lifespan: The designed lifespan of the battery is 27 months. For typical family cars, which are more economical, new car batteries can often last 3-4 years. However, after the first replacement, they generally need to be replaced every 2 years or so. Taxis are more demanding—single-shift taxis can last a little over a year, while double-shift taxis last around 8-10 months.
I often drive long distances in 24V heavy-duty trucks. Using a car fan for rest during the trip is quite comfortable, but how long it can last after turning off the engine depends on the battery condition and the fan's power consumption. From my experience, the fan's power is generally between 100 to 150 watts, with a current of 4 to 6 amps. If the truck's battery capacity is large, it can reach around 150Ah, theoretically lasting up to 20 hours. However, in reality, battery aging or high temperatures can reduce capacity, making it safer to expect only 10 to 15 hours. Once, I forgot to turn off the fan overnight, and the next day, the truck wouldn't start, causing a big hassle. Therefore, I recommend not running the fan for more than 8 hours, setting an alarm to turn it off while sleeping, or equipping a solar charger to supplement the battery, to avoid delaying the trip and affecting your mood. Most importantly, keep an eye on the battery voltage to ensure it doesn't drop below 12V.
As a car enthusiast who has worked on many vehicles, estimating how long a 24V car fan can run after the engine is off isn't too difficult. The fan's power typically ranges between 80 to 120 watts, drawing about 3 to 5 amps. Calculating with a standard truck battery of 80Ah, theoretically it should last 16 to 26 hours. However, real-world usage differs: running the fan at maximum speed or adding small lights drains power faster, and an aged battery with reduced capacity might only last half that time. In my own vehicle tests, a new battery showed the red warning light after about 10 hours of fan operation, while an old battery might only last 6 hours. To prevent being unable to start the next day, I usually set the fan to run for 4 to 6 hours, or install a voltage monitor for peace of mind.
