Posts: 43
Threads: 10
Joined: Jan 1970
Thanks Randy and Dave,
Wow, that is pretty high, thanks for measuring it for me. I know the charging current on the Woodstock is going to depend on whether the calculator is on, as well as the battery voltage. But I would not have thought it could provide 200mA throught the charging circuit. That may explain why the resistor in the charging circuit got pretty warm while charging.
If the charging circuit is a simple resistor and diode setup as Dave Smith has mentioned, it is just a half-wave rectifier with a unidirectional pulsating waveform as output (with both DC and AC components). I wonder if that might have confused the Fluke if it does not has AC+DC RMS capability (I know the Fluke 45 has it, but it is 3 decades ahead of my Fluke 8000A). If the meter only display the peak current, then the RMS value is only 35% of the peak (half wave), which would put the RMS current in roughly the 71mA RMS.
Could this be a possible scenario? I wouldn't have thought the old 600mAH NiCD battery from the 70's could even take a 200mA continous charge current.