When a BatteryPool has no usable batteries, it sends out a None value for SoC, Capacity and PowerBounds, indicating that these values are not available, in the absence of working batteries.

We need to figure out how this information can be more clearly represented.

One option is in the case of SoC and Capacity, which stream Sample objects, we can just set the Samples value to None instead. And provide a similar mechanism for the PowerBounds as well.