HP92266 N cell charger

[TASP]

Received the Interstate Batteries NiMH rechargable N cells, and figured they were worth a try in the 'official' HP92266 charger.

As received, the cells had a voltage ~ 1.25 volts. I'm not sure what % charge that translates to. I was able to load 3 cells normally, and then cant #4 so I could put my milliampmeter in series with the pack.

At the start, the current was close enough to 16 mA. Overnight charging (and then some) and a removed cell after a 1/2 hour or so wait, shows a voltage of 1.4 volts.

I then put the cell back in the charger and measured the charging current at 14 mA.

Assuming, an average of 15 mA for a full charging time, the math for a 500 mAH capacity comes out to 33 hours.

Meh, that ain't bad. Back in the 80s, I just left a set of NiCADs in it all the time. I've checked around, and NiMH cells in emergency lights, and other standby applications seem to survive trickle charging OK, so if I did leave a set in the charger for a year, it probably isn't a disaster.

As it is, I'll charge sets (I have 3, so far) for 48 hours, and then bag them and and put them in the kitchen battery drawer, ready for another stint in a 41.

Nice after all these years in storage the charger still works. And since I am finding the collecting aspect of this HP calculator world to be fun, having the HP N charger up and working in this modern era with new battery chemistry just makes it all the better.