Red Seal Electrician Practice
DC circuitsQuestion 791 of 1506

In a series battery bank, why must the batteries have the same amp-hour rating?

  1. Each battery has a different voltage
  2. The same current flows through all, so a smaller one runs down first
  3. The batteries share the load current equally, so any size is fine
  4. The bank voltage is the average of the batteries
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Correct answer: The same current flows through all, so a smaller one runs down first

Current is equal in a series circuit, so the weakest battery is depleted first and limits the bank.

Source: Lessons in Electric Circuits I: DC (Kuphaldt), 11.5: Practical Considerations - Batteries

Practice dc circuits

Questions last reviewed: 18 October 2026