A bit strange but somewhat related...I am fairly well versed with lipo batteries. i had 3 batteries all charged up and ready to go but the weather wasn't cooperating so the batteries sat in my bag for a few days.
When I did fly this past weekend, I noticed that the batteries said 98% when I was taking off but the actual cells were in the 3.78v or so range. I was expecting them to be more like 4.15v.
I kept a really close eye on the voltage as I was flying and I took it easy to reduce the risk of voltage sag from rapid acceleration, etc.
I eventually landed all of my flights with around 60-70% battery remaining (about 10 minute or so flights) and even as the battery drained, the voltage did not drop much (was above 3.7v when landed).
I thought it was odd but didn't think much of it until I read through this today.
The plane landed here due to low battery. Why it was such a low voltage is odd and usually is the result of auto discharge but I didn't think it started to do that until 10 days. I was definitely at less than 10 days (more like 4 days or so).