I’m working on a real simple lab for my circuit analysis class, but I’m having a hard time sourcing information to make sense of my results. Part of the lab was to hook up a 2 AAs, and a 0.5ohm resistor in series and measure the voltage across the battery terminals every minute for 15 minutes. Initially we measured 3.0V open circuit, and about 1.8V across the battery, and by the end, it had decreased to 0.37V. BUT, after unloading the batteries, the open circuit voltage went back up to 2.56V. It makes sense that the battery had discharged so it lost some of its voltage. However, I don’t understand why the voltage across the load kept dropping. By the 15th minute, the calculated internal resistance was about 3ohms, while it had been about 0.3ohm at the very start. I thought it had to do with the battery heating up like a PTC which caused the resistance to go up…but after reading about batteries, it seems that the internal resistance of a battery goes down with increased temperature. What am I missing!? Thanks so much!