HP41c battery pack refurbished with micro USB connector.

[Dieter]

(07-08-2016 07:14 AM)isanchez Wrote:  I have refurbished an HP41c battery pack with new batteries and what makes it more special is that it can be connected to any mobile phone charger or to a laptop through a micro USB connector implemented. As I have removed all the circuit stuff

OK, but where is the charging circuit then? Connecting the batteries directly to the 5 V of an USB port is not a good idea at all as there is nothing that sets the correct charging current and you also do not know the charging time for an empty pack.

After all there was a reason for the "circuit stuff" inside the original 82120A. ;-)

USB ports or USB AC-adapters are not chargers. They just provide a voltage and a certain maximum current. Also 5 V are not sufficient to charge a pack of four NiMH batteries. This means that as soon as the cells reach 1.25 V each there is no current that could charge them. Compare this to a freshly charged NiMH which will read about 1.4 Volts and more.

Sorry if this sounds a bit sceptical, but I am curious how you did it. Maybe there is something I overlooked here?

Dieter