Depending on the TV, it can be slightly difficult to determine if your TV is, in fact, charging the battery on your R-pod.
For example, the Bargman (AKA "7-pin") connector on our F-150 is a "smart connector". The F-150 does not provide power when the truck is off. It also does not provide power if there is no trailer connected. As a result, you can't just check for voltage by probing the 7-pin connector, regardless of whether the truck is running or not.
The way that I check it is to look at the voltage on the R-pod batteries. First, the trailer must be connected, and second, the truck must be running. When the truck is off, the batteries on the R-pod will be at their static voltage, which would be in the very high 12V range, or "around" 13 volts, depending on their state of charge (this is presuming they are pretty full). When the truck is started and the trailer is connected, the voltage at the R-pod batteries should jump up about a volt or so (~~ 14 volts).