Hi,
A maybe pedantic clarification:
This may sound as if the batteries determine the current.
But usually the current is determined by the load.
No connected load = no current.
Klaus
Sorry that I was not clear enough.
When I said that the battery will have a voltage of about 3V, I meant the open circuit voltage (no load connected).
Similarly when I say that the batteries may deliver about 1-3A current, I meant the short circuit current (a load with zero resistance is connected).
Without any load connected, the battery will have the highest voltage (open circuit)
With a load of zero resistance connected, the battery will have highest current (short circuit current)
Why these are relevant? Because all real batteries have some finite internal resistance. Ideal batteries have zero internal resistance (ideal voltage source) and their potential does not change when you connect with the load. When shorted, they can supply infinite current. Unfortunately ideal voltage sources do not exit.
The internal resistance of a battery becomes important when you consider the real power delivered by the battery to an external load. Because of the internal resistance, all batteries cannot deliver arbitrary power to an external load. Max power is delivered to an external load when the load resistance is equal to the internal resistance of the battery.
I am very sorry that I was not explicit enough.
The current into a load is determined by the load.
The max current that the battery can deliver is determined by the internal resistance of the battery.
The actual current a pair of D-cells can deliver into a load of zero resistance will be perhaps around 1-3A but this number is a guess. It will vary with the brand and will continue to drop during its useful life.
When you short the battery terminal, the terminal voltage drops to zero and the current becomes large.
When the load is absent, the terminal voltage reaches the max value but the current is now zero,
I hope I am bit more clear now.