HP 67: charging of battery pack

[PANAMATIK]

(04-26-2017 05:34 PM)BobVA Wrote:  The HP-67 manual I've got (later printing, maybe?) also has a warning about not operating the calculator without a battery pack.

Maybe Tony Duell is right about the HP-65, I don't know its connection scheme, but not about the HP-67.

I just tried following with my HP-67.

1.) I removed the battery pack, plugged in the charger and switched On. OK calculator works well.
2.) I inserted the battery pack, plugged in the charger and swicthed On. OK calculator works well.
3.) I removed the charger from the mains, while calculator is still swicthed On. The calculator gets dark, has no voltage, because the battery is disconnected.
4.) I removed the plug from the charger slot, while calculator is still swicthed On. The calculator starts up, because now the battery is connected again.

This proves that the battery is not connected while charging. How can a battery influence the voltage, if it is disconnected?

The warning not to use the calculator without batteries should nevertheless be followed. Maybe it is just a warning, that the current for the card reader is not strong enough without batteries but there will be no circuit damage.

Bernhard