Lead-acid battery power meter display is inaccurate

Lead-acid batteries are highly sensitive to temperature. Testing should ideally be conducted at room temperature to ensure accurate results. Extremely high or low temperatures can skew the results of voltage, capacity, and resistance tests. To ensure optimal performance, it is recommended to perform battery testing at regular intervals.

To get a more accurate reading of a lead-acid battery's health, you can use a hydrometer. This tool measures the specific gravity of the electrolyte solution within the battery, which can give you a better idea of its state of charge and overall condition. Before using a hydrometer, it's important to make sure the battery is fully charged.

Figure 2: Voltage band of a 12V lead acid monoblock from fully discharged to fully charged The hydrometer offers an alternative to measuring SoC of flooded lead acid batteries. Here is how it works: When the lead acid battery accepts charge, the sulfuric acid gets heavier, causing the specific gravity (SG) to increase.

Impedance Testing: Comprehensive Health Assessment Lead-acid batteries degrade over time due to several factors, including sulfation, temperature fluctuations, and improper maintenance. Testing these batteries at regular intervals allows us to detect potential problems early, ensuring longevity and optimal performance.

A higher-quality meter would likely give you more accurate results, which in this case should be 0V AC for both batteries. To confirm whether your meter is actually broken or not, you could put it on AC and (very carefully) measure the voltage at a wall socket. Make sure your meter is rated for the wall socket voltage!

Lead acid comes with different plate compositions that must be considered when measuring SoC by voltage. Calcium, an additive that makes the battery maintenance-free, raises the voltage by 5–8 percent. In addition, heat raises the voltage while cold causes a decrease.