Internal resistance refers to any material’s opposition to the flow of energy through a conductor. This level of impedance varies between different substances, though. This differential comes in handy when designing electronic circuits. However, internal battery resistance may be a more serious matter, for it affects the efficiency of individual cells. We delve into this process, and then explain how to measure resistance in a battery.
Why the Need to Measure Battery Internal Resistance
The strength of internal opposition to the flow of current through a battery affects its overall ability to deliver. If the level of internal battery resistance is low, then the cells in the battery can cope with a significant amount of current. However, if the measure of this impedance is high, then the opposite generally applies.
We should therefore not be surprised when topic specialists like Ricky Luo on LinkedIn describe ongoing efforts to lower internal resistance in lithium-ion batteries. Ricky goes on to explain how this factor “plays a pivotal role in a battery’s overall performance” as follows:
- High resistance in a battery causes voltage losses and robs it of some power.
- Greater internal resistance means losing more of this energy to friction heat.
- Increased heat can make batteries become warmer affecting thermal safety.
This internal resistance factor gradually increases as batteries age, due to rust and corrosion. Batteries in critical roles should have their resistance checked during maintenance to determine what is happening inside.
An Insider View of Resistance in a Single-Cell Battery
Single-cell AA and AAA batteries are low voltage, and should not harm us while measuring battery resistance as we describe below:
- To determine a single cell battery’s internal resistance when not under load, set a multimeter to measure resistance. Then touch the probes to the positive and negative terminals. Your reading should be no more than a few ohms.
The value of this result should gradually increase as a battery ages. Follow several identical batteries through their useful lives in the same way. Use the benchmark average result you obtain to monitor similar batteries in future. That way, you can predict when it is time to consider replacing them.
More Information
Volts, Currents, and Resistance in Batteries
Electrical Resistance : School Experiment
Preview Image: Resistance Versus Temperature
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