Lead Acid Battery Overcharge: Causes, Prevention, and Proper Charging Techniques

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A stack of lead-acid batteries with the Moko Energy company logo, accompanied by text discussing lead acid battery overcharge, its causes, prevention methods, and proper charging techniques.

Charging is crucial as it aims to maximize lead-acid batteries’ performance and life. Overcharging results in higher battery temperature, higher gassing rates, higher electrolyte maintenance, and corrosion of components, while repeated undercharging leads to a gradual reduction of battery capacity, which is sometimes irreversible. To determine an effective charge procedure the relationship between the available capacity of the batteries, the overcharge applied and the DOD level before charging had to be defined. This blog will discuss the problems concerning lead acid battery overcharge, introduce the three stages of the CCCV charge method, and offer practical advice on how to avoid overcharging and prolong the battery’s life.

Understanding Lead-Acid Battery Overcharge

What is Lead-Acid Battery Overcharge?

Consequences of Overcharging

Charging a lead acid battery at high temperatures can cause serious damage to the battery and even lead to explosions. When a battery is overcharged, it may experience:

In extreme cases, overcharging may also result in an explosion or fire, which can be hazardous to users.

How to Properly Charge Lead-Acid Batteries

A graph illustrating the three stages of constant-current, constant-voltage (CCCV) charge methods for lead-acid batteries. The graph shows how voltage per cell and charge current vary over time during each stage - constant current charge, topping charge where current drops, and finally the float charge stage to maintain voltage level.
(Pic via BatteryUniversity)

Stage 1: Constant-Current Charge

  • During this stage, a constrained steady current is administered onto the battery causing the terminal voltage to increase.
  • The battery charges from 0% to 70% of its capacity.
  • This stage indeed takes 5-8 hours.

Stage 2: Topping Charge

Stage 3: Float Charge

The first stage of charging from the constant current charge to the topping charge moves automatically to stage 2 when the battery reaches the battery voltage set at stage 1. This current then starts to decrease as the battery is beginning to approach the state of being saturated. Charging is deemed complete when the current tapers off to 3- 5% of the Ah specification.
The plateau timer will be employed in order to stop the charging of the battery if the leakage is high or if the low saturation current fails to be attained. The total charge time for lead-acid batteries using the CCCV method is usually 12-16 hours depending on the battery size but may be 36-48 hours for large batteries used in stationary applications. Using multi-stage charge methods and elevated current values can cut battery charge time to the range of 8-10 hours, yet without charging the toy to topping levels.
But it is important to note that lead-acid batteries cannot be charged any faster than this system charges them and CCCV is an acceptable choice because it is slow and safe for the batteries.

How to Properly Charge Lead-Acid Batteries

Understanding Manufacturer Guidelines

Using Proper Charging Equipment

Monitoring Charge Levels

Battery TypeCharging Voltage (V)Float Voltage (V)
12V Lead-Acid14.4 – 14.813.2 – 13.8
6V Lead-Acid7.2 – 7.46.6 – 6.9

Table: Ideal Voltage Levels for Lead-Acid Batteries

How to Prevent Lead-Acid Battery Overcharge

Smart Charging Techniques

Smart charging machines are charged using microprocessors that control and regulate the charging process in such a way can ensure not overcharge the battery.

Battery Management System

Regular Maintenance

Environment and Usage Considerations

Ensure Battery Longevity with Mokoenergy’s BMS


  • Real-Time Monitoring: Tracks voltage, current, and temperature.
  • Automated Control: Adjusts charging parameters to prevent overcharge.
  • Fault Detection: Identifies and alerts users to potential issues.
MokoEnergy’s Lead Acid BMS

Mokoenergy’s BMS employs intelligent algorithms to maintain optimal charging conditions. It constantly checks the condition of the battery and prevents the battery from overcharging as well as increases safety and reliability and ensures longer battery lifespan.

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