# Why does the measured potential-difference between two poles of an AA fizzle out after 5 seconds?

I have some AA and AAA batteries that are sitting on my desk - I decided to test them before throwing them out. Some are Duracell "Duralock" brand, the others are Kendal "Super Heavy Duty - Pile Saline".

I recently bought a Fluke 115 multimeter, so I decided to use that to measure the voltage between the positive and negative poles of the battery.

I set the multimeter to DC V mode; when I attach the probes to the battery (red on the positive terminal, black on the negative terminal) the display reads 1.329 V for about 5-10 seconds, then the number suddenly drops to 0 V over about 2 seconds, then it stays there.

This happens consistently with the other batteries on my desk (the initial voltages are all around 1.3-ish Volts) except one, which stays at 1.329 V and never drops.

What is happening?

• The cell is almost out of reactants. – Ignacio Vazquez-Abrams Nov 26 '16 at 22:40
• The ones that go to 0 are dead. throw them out. The ones that stay above 1.0V are still OK to use (in some products - try them and see). Technically, you need a load resistor, like 27 ohms, to test the health of the AA or AAA. – Rich S Nov 26 '16 at 22:44
• @RichS But why do they start at 1.3V and then drop? Why aren't they 0V from the beginning? – Dai Nov 26 '16 at 22:46
• They are probably just very old, and were not used. From age, their internal resistance increased, because of internal chemical reaction. Do they have date codes? – Rich S Nov 26 '16 at 22:48
• Make sure that your probes were not connected to the mA socket. – Andy aka Nov 27 '16 at 10:33