Here are snippets for data collection and graphs from newer DELL DRAC models. This has been tested with a M1000e blade chassis management controller. It collects current and power usage from the chassis and its 6 associated PSU units.
I don't have access to newer DRAC cards in "regular" PowerEdge servers, but in theory it could collect data from these, too. Comments welcome. At least the updated <systemDef> does not seem to break collecting from older DRAC cards without power reporting.