Should Lead-Acid Batteries Be Charged After Use or Frequently?

From an environmental perspective, lead-acid batteries should be charged strategically. Frequent unnecessary charging wastes energy and increases carbon footprint. Charge only when voltage drops below 12.4V. Proper disposal and recycling are critical—98% of lead-acid batteries are recycled, but overcharging shortens lifespan, creating more waste.

Lead-acid batteries should be charged frequently. Even if the battery is only 10% depleted, charging it at this stage can have an impact. When charging, once the charge level exceeds 90%, you can stop charging when the red light on the charger turns green.

Proper maintenance methods for lead-acid batteries:

1. Regular Deep Discharge:

Perform a deep discharge every two months until the under-voltage indicator lights up and the battery is fully depleted. Then recharge to restore battery capacity. This helps assess the current capacity level and determine if maintenance or protection is needed.

1. Avoid Storing with Low Charge:

Storing a battery with insufficient charge severely affects its lifespan. The longer it remains idle, the more severe the damage.

1. Regular Inspection:

A fully charged battery should typically measure 39-42V. If the voltage is significantly lower, or if one cell in the battery pack shows a voltage below 10.5V when opened, there may be an internal short circuit. Seek repair at a service station to avoid damaging the other healthy cells. Additionally, check the charger for faults.

1. Avoid Overloading:

Electric assist vehicles are designed for a load capacity of 75kg. Avoid overloading. Use pedal assistance when starting or climbing hills, as the motor current increases during these times, leading to rapid battery discharge and voltage drop.

The shallower the depth of discharge each time the battery is used, the longer its lifespan. Therefore, reducing high-current discharge can extend battery life and increase continuous driving range. Regardless of the battery size, develop the habit of charging as needed.

1. In winter, battery capacity decreases with temperature, which is normal. At -10°C, the capacity is typically 80% of that at 20°C.

1. Keep the battery surface clean for extended periods and avoid exposing lead-acid batteries to direct sunlight. Store them in a cool, ventilated, and dry place.

Lead-acid batteries, commonly found in traditional petrol and diesel cars, should be charged after use if they’ve been significantly drained (e.g., short trips with frequent starts). However, frequent charging when the battery is already near full capacity can reduce its lifespan.

For optimal performance:

1. Charge after heavy use: If the battery voltage drops below 12.4V (measured with a multimeter), recharge it promptly to avoid sulphation, where lead sulphate crystals form and degrade capacity.
2. Avoid overcharging: Modern chargers with automatic cut-off are ideal. Overcharging causes excessive gassing and water loss in flooded lead-acid batteries.
3. Maintain charge levels: If the car sits unused for weeks, use a maintenance charger (trickle charger) to prevent deep discharge.

Examples like the Ford Focus or Vauxhall Corsa with standard lead-acid batteries benefit from this approach. AGM (Absorbent Glass Mat) batteries, often in stop-start vehicles, tolerate deeper discharges but still require careful charging.