I don’t have a way to measure power consumption in terms of voltage, but I guess I could find some kind of battery monitor/logger and run it on battery until it runs dry. Doing that with different CPU frequency settings would provide a comparison. My batteries are not new, but they should be in pretty good shape and fairly representative.
Any suggestions for a battery monitor/logger, and I suppose something to run to keep the system busy until it drains the battery? 
Ok, for logging, I think I can use the excellent work done here. I just checked and the script works on devterm as well as gameshell, so I should be able to log voltage, battery capacity, and current over time. I just need to come up with something that taxes the CPU and drains power fairly quickly. Suggestions welcome!