T4A09 - How can you determine the length of time that equipment can be powered from a battery?

Question

How can you determine the length of time that equipment can be powered from a battery?

Answer Options

  • A) Divide the watt-hour rating of the battery by the peak power consumption of the equipment
  • B) Divide the battery ampere-hour rating by the average current draw of the equipment
  • C) Multiply the watts per hour consumed by the equipment by the battery power rating
  • D) Multiply the square of the current rating of the battery by the input resistance of the equipment

Correct Answer: B


Explanation

Battery capacity is rated in ampere-hours (Ah), which is the amount of current (Amperes) the battery can deliver for a specific period (Hours). Equipment consumption is measured by its average current draw (Amperes).

To find the length of time (Hours) you can operate, you simply perform a division: \text{Time} = \text{Capacity (Ah)} / \text{Current Draw (A)}. For example, a 12\text{ Ah} battery powering a radio drawing an average of 1.2\text{ A} will last for 12\text{ Ah} / 1.2\text{ A} = 10 \text{ hours}.


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