I just noticed my charger was unplugged for my 300x, and I have more battery life than I did when I took it out this morning. The only thing I can think of is that I'm charging over USB, since that's been plugged in the whole time.
I love finding neat features a few years after the fact.
I'm surprised usb will provide enough amperage to charge a battery pack along the size of the one in the Rangers. I guess if you really want to prove this, run the Ranger battery down really low, and leave it connected to a computer over night or something and see if it is charged up in the morning.
The older TSCe devices had a program to monitor the battery chagre status, I've used it to detect bad batteries. On the TSC2 (=TDS Ranger 300) it is replaced by the program 'Battery Logger', never used it before.
You'll find it in your Programs screen, worth a check to monitor your battery status.
To start logging tap the Tools button at the button.
chr.
I'm not sure where your from, but did it just warm up over night and give you a little more juice?