Extended-use rechargeable battery 92266B

[Renato]

Just curious : HP-41 peripheral booklet lists Extended-use rechargeable battery 92266B and Extended use charger 92266A. I´ve never seen these - even in pics. Does anyone have them ?

[David Smith]

They were full sized nicad "N" cells for use in the standard alkaline battery holder. These cells were charged externally to the machine.

[Renato]

David, thank you for the information. Do you know how the external charger looked like ?

Renato

[David Smith]

If I remember right it was a little black box with four slots for the batteries. It was powered by a wall wart. I have also seen a version that was designed for AA batteries, but had little adapter cradles for the "N" cells.

[Renato]

The version for AA batteries would be HP branded ? I know radio shack used to sell AA charger , n-size batteries and adapters for charging n-size on the aa charger (it was described in this forum).

Renato

[David Smith]

I think the "AA" adapter solution was not from HP, but sold by some of their distributors or dealers (mayby Educalc). I have seen the same model charger/adapters with several different machines.

[Ellis Easley]

I looked in my old HP catalogs earlier in this thread but didn't find this. But when David mentioned EduCalc, I looked in those catalogs and there is a picture of the product. I'll scan the page and email it if you want. It might be in one of the EduCalc catalogs on the Museum CD-ROMs.

Next to it is another brand NiCad charger with optional sleeves for N cells. Wouldn't it be necessary to reduce the current for N cells from what is being put out for AA cells? A PPC Journal article I referenced in another thread suggested using a AA charger with a resistor to reduce the current for the N cells. Putting a resistor in series would depend on knowing what the voltage is inside the charger. But assuming the charger was putting out 50 mA for a AA, and the voltage of a cell is nominally 1.2V, and wanting say 15 mA for the N cell, you could put a resistor in parallel to draw the extra 35 mA and it would be 1.2V/35mA=34.3 ohms and dissipate 42 mW. 34 ohms is a standard 1% value and a 1/4W resistor would do. A 33 ohm 5% resistor would draw a little more than 36 mA (with more latitude!) and would do about as well.

[Ellis Easley]

The 92266A and B are in educ85.pdf which is on CD5, on page 12. "A" is the recharger with 4 cells, "B" is 4 more N cells. There is also a different solution from the same 3rd party I mentioned before (Ledford Micro) which includes a recharger made for N cells.