Real-world battery behavior under load In practical electrical applications, how does the terminal voltage of a battery respond as load current increases?

Introduction / Context:
Batteries are not ideal voltage sources. Their terminal voltage depends on chemistry, state of charge, temperature, and internal resistance. Recognizing how load affects terminal voltage is crucial for sizing supplies, predicting run-time, and avoiding brownouts in embedded systems.

Given Data / Assumptions:

• Battery has nonzero internal resistance r_int.
• Load draws current I that can vary with operating conditions.
• Open-circuit voltage Voc is approximately constant over a portion of discharge.

Concept / Approach:
Model the battery as an ideal source Voc in series with r_int. The loaded terminal voltage is V_load = Voc − I * r_int. As the load current increases, I * r_int increases and the observable terminal voltage drops (voltage sag). When the load is removed, the voltage rebounds toward Voc.

Step-by-Step Solution:

Verification / Alternative check:
Observe any portable device: high current bursts (e.g., radio TX) cause momentary voltage dips; removing load restores voltage toward open-circuit level.

Why Other Options Are Wrong:

• Immediate restoration upon disconnect: rebound occurs, but that does not describe behavior under increased load.
• Stored indefinitely: batteries self-discharge and age.
• Reduced to zero as power is drawn: only true at end-of-life/faults, not a general rule.

Common Pitfalls:
Ignoring temperature effects that change r_int; cold batteries sag more under load.

Final Answer:
It is lowered as the load increases (due to internal resistance).