HP Forum Archive 15

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Charging current for Woodstock and Spice Message #1 Posted by Gordon on 12 June 2005, 7:18 p.m. Does anyone know the charging current for the Woodstock and the Spice series? Is it is the 50-60 mA range as in the Classic? Thanks in advance.

Re: Charging current for Woodstock and Spice Message #2 Posted by Randy on 12 June 2005, 10:11 p.m., in response to message #1 by Gordon As measured on several Woodstocks and a reserve power pack: ~200 ma. Seems high but that's what the Fluke says. One functional Spice checked in at 130 ma. All values measured in series with a good battery in need of charge. Edited: 12 June 2005, 10:20 p.m.

I wonder if the rectifier may confuse the Fluke Message #3 Posted by Gordon on 15 June 2005, 1:05 a.m., in response to message #2 by Randy 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.

Re: Charging current for Woodstock and Spice Message #4 Posted by David Smith on 13 June 2005, 3:18 p.m., in response to message #1 by Gordon The charger is just a diode and a resistor in series. The current varies (drops) as the pack charges up.

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