Charging current for Woodstock and Spice

[gordon]

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.

[Randy]

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.

[gordon]

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.

[David Smith]

The charger is just a diode and a resistor in series. The current varies (drops) as the pack charges up.