What Causes Low Battery Power?
4 Answers
The reasons for low battery power are: 1. Insufficient power generation from the alternator; 2. Battery aging or damage, resulting in insufficient charge retention; 3. Low rated capacity of the battery; 4. Vehicle has electrical leakage or excessive standby current; 5. Using electronic devices while the vehicle is parked; 6. Frequent short-distance driving. The battery charging method is: 1. Turn off the engine and remove the battery; 2. Open the vent caps on the battery; 3. Attach the red clamp of the dedicated charger to the battery's positive terminal marked with a plus sign, and the black clamp to the negative terminal marked with a minus sign; 4. Adjust to the 2nd gear and select 12-volt power supply; 5. Plug in the charger, turn on the switch, and start charging.
I've been driving for over a decade and have encountered dead batteries quite often. The most common scenario is leaving the car unused for too long, like returning from a two-week business trip when starting the engine becomes particularly difficult. Later, I got smarter and started disconnecting the negative terminal if the car wasn't going to be used for more than two weeks. A friend of mine always drives short trips of just two kilometers, turning off the engine before the battery fully charges, and ended up needing a new battery in less than a year. Also, in-car devices matter—I once saw someone run the AC for half an hour after turning off the engine, and the car wouldn't start the next day. So now, I always turn off all electrical devices before shutting down the engine, especially always-on devices like dashcams. I recommend checking the battery voltage with a multimeter every three months; if it's below 12.4 volts, pay attention. Be extra cautious in cold weather—batteries are particularly prone to dying in Northeast China's -20°C winters.
Many car owners often complain about battery issues during repairs. In fact, 30% of the problems are caused by the generator, such as loose belts or faulty voltage regulators, which prevent proper charging and lead to power loss. During inspections, it's common to find batteries older than four years with severe sulfation on the electrode plates, making them unable to hold a charge. Once, a customer's car had a dome light that wouldn't shut properly, draining power even after locking the car. Modified cars are even more troublesome—for example, subwoofers installed without a relay can secretly drain power after the engine is off. Using a clamp meter to measure the static current, anything over 50 milliamps indicates a problem. It's recommended to replace batteries older than three years and ensure the generator voltage reaches 14 volts for normal charging. Regularly cleaning the battery terminals can prevent poor contact and unnecessary power drain.
Last time after a trip, my car wouldn't start, and the diagnosis showed battery self-discharge. The mechanic said the battery loses 1% charge daily during long-term parking. Now I disconnect the negative terminal when not using the car for over ten days. Short trips are indeed problematic—daily 3 km round trips to take the kids barely charge the battery. Switching to an e-bike for short trips noticeably improved my car battery's lifespan. Once, I forgot to turn off the reading light overnight and the battery died, but I successfully jump-started it with a power bank. Now I keep an emergency power source in the glove box. When installing a dash cam, remember to connect it to the ACC line; constant power connection really drains the battery. Also, watch out for old cars with aging wiring that may leak electricity.
