Motor Expo 2026

During long holiday seasons, many people take this opportunity for a month-long break to relax or conduct business abroad. This means leaving their cars parked for extended periods without anyone to start or warm up the engine. Now let's see> They say… : If you park your car for more than 1 month, you must disconnect the battery terminals…is that true? The answer is... True: Why? Let's find out.

When we leave a car parked for months, the electric charge in the battery will decrease by almost 1% per day, and in some areas, current leakage may occur. If you want to maintain a battery that has not been used for a long time (more than 1 month) to still have charge remaining, you must disconnect the wires from both terminals, both positive and negative, then wipe the top part of the battery and the base of the terminals clean to prevent current leakage through the moisture on the battery casing. Anyone who owns a car but doesn't use it often will understand that if you park a car for a long time and then want to start the engine, it feels like the starting power from the battery is insufficient, even though the battery was just replaced less than a year ago. This is because our car's electrical system has the potential for current leakage in some positions, and even if there is no leakage, if it doesn't receive electrical charge from the alternator into the battery, the electrical charge will still decrease by almost 1% per day (external temperature not exceeding 30 degrees Celsius). But this doesn't mean it will be completely drained within 100 days; it means the capacity on the next day will be about 99% of today's capacity.

Therefore, if you want to maintain a battery that has not been used for a long time (more than 1 month) to still have battery charge remaining, do not leave the battery with both terminals (positive and negative) connected to the car's wiring. You must disconnect the wires from both terminals and wipe the top part of the battery, including the base of the terminals, clean to prevent current leakage through the moisture on the battery casing. If you have to park the car in the sun or in high ambient temperatures, remove the battery and store it in the coolest place you can find, because heat will cause the battery's charge to decrease rapidly, even if it's not in use. If you want to know how many percent of today's capacity will remain after 15 days, multiply 0.99 by itself 15 times, or raise it to the power of 16 and multiply by 100, which will give you approximately 0.85, then multiply by 100 to get 85%. If stored in a hotter and more humid place, it will be less than this. Therefore, the suitable place to store a battery that has not been used for a long time is a cool, dry, and clean place, meaning no dust. Importantly, do not leave the battery in a state with no or very little charge, as this will cause sulfate to firmly accumulate on the lead plates. A battery that has been completely or almost completely drained, such as forgetting to turn off the lights or radio, or an engine problem that caused it to be cranked until the charge is almost gone, if you don't have a charger yourself, you must quickly remove it and send it to a battery shop to be recharged as soon as possible.

Source autoinfo.co.th