How often do you change the batteries? I feel like my temps have been a little wacky this month and last. In the mornings, I take the temp, and since its still dark in the room, I turn it off and then when I am up with the lights on, I turn it back on and it shows the temp from memory. This morning, I was hoping for it to show the ovulation spike and it just showed 96.8. I was just going to take my temp again this afternoon to see if maybe the battery is going. As I turned it on, it showed a temp from memory at 98.7. Weird. I had a pos opk a two days ago and yesterday was the end of my ewcm, so I am hoping I did ovulate when I thought and the temps are just off. I've had the thermometer since July, maybe.