# Why does battery generate less terminal voltage difference when current flows?

The terminal voltage difference of a battery means the difference of voltage between the two termials of a battery. Now, a battery has a voltage at the positive terminal and a voltage at the negative terminal. Voltage means the work needed to be done to bring a poistive one coulomb charge from infinity to that terminal. Now, how does the value of this work change when current flows? (The value of this work must change for both of the terminals for the terminal voltage difference to be changed, isn't it?) I want an intuitive explanation.

• A real battery is not an ideal source of energy, sustaining constant voltage no matter how much current flows. A real battery, for a first approximation, can be modeled as an ideal battery with a resistor. Real life, as always, is far more complicated. Commented Jul 28, 2017 at 16:30
• Model the battery as a voltage source in series with a small resistor and it will all make sense. Commented Jul 28, 2017 at 16:31
• RE: " Voltage means the work needed to be done to bring a poistive one coulomb charge from infinity to that terminal."---never mind this. Think more about the potential difference between one terminal and the other. That tells you how much work the chemical reaction in the battery is doing to move charge from one terminal to the other. Commented Jul 28, 2017 at 18:07