In amateur radio practices, what does excessive internal resistance of a battery cause?

Excessive internal resistance in a battery leads to an inconsistent voltage supply due to the battery's inability to deliver current effectively. When a battery has high internal resistance, the voltage drops more significantly when a load is applied, especially under higher current demands. This drop can result in unpredictable and varying voltage levels, affecting the performance of connected devices or equipment that depend on a steady supply of power. The inconsistent voltage can lead to operational issues, including diminished performance of the amateur radio equipment, which relies on stable voltage levels for optimal operation.

In contrast, lower internal resistance is generally desirable in batteries, as it allows for a more consistent voltage output and better performance under load, enhancing the overall reliability of the power supply in amateur radio setups.