Palmtronic LC-5 battery

[Thomas Puettmann]

I have just unearthed the calculator that I used before I got my first HP:

A Canon Palmtronic LC-5, that was once given to my dad as a gift from his company Graetz/SEL/ITT.

There was no battery inside. It seems I had removed it way back in approx 1986. Searching the internet by "Palmtronic LC-5 battery", I find CR 2025 as the only recommendation. To me, it seems that a CR 2025 is too small and a CR 2325 would be more appropriate.

The manual says: "Use a LF 1/2 W", whatever this means. I couldn't find any information about this ancient battery type.

It works with a CR2025 but the numbers in the display are not as dark as they should be.
   
Anybody any kind of information?

I did not make up my mind yet whether I want to keep or sell this elegant calculator. But I would guess that it is not on the wish list of many calculator enthusiasts. Am I right?

[Bill (Smithville NJ)]

(01-27-2023 02:37 PM)Thomas Puettmann Wrote:  There was no battery inside. It seems I had removed it way back in approx 1986. Searching the internet by "Palmtronic LC-5 battery", I find CR 2025 as the only recommendation. To me, it seems that a CR 2025 is too small and a CR 2325 would be more appropriate.

The manual says: "Use a LF 1/2 W", whatever this means. I couldn't find any information about this ancient battery type.

Are you sure it says "LF 1/2 W" and not LF 1/2 V"? I found several cross references to LF 1/2 V.

When you say CR2025 is too small, do you mean thickness, diameter, or both?

The CR2025 is 20x2.5.
The CR2032 is 20x3.2.
The CR2430 is 24.5x3.0.


You might want to try the CR2430 if you can find one.

73
Bill WD9EQD
Smithville, NJ

[Jeff_Birt]

Doing a search for "LF 1/2 W" I found the following:

https://batteryguy.com/genreic%20battery...ttery.html

Judging by your photo I think you would want something with a larger diameter than 20mm though. It also seems the 3.2mm thickness of the above battery might be too much for your calculator.

The coin cell sizing is easy to figure out if you did not know already. Frist two numbers are diameter in mm. Second two are thickness in 0.1mm (32 = 3.2mm)

[Thomas Puettmann]

Thank you to both of you for your help!

The height of the CR 2025 seems to be ok.

The back of the battery cover has a lowering with a diameter of 24.5 mm, hence from your information I guess the CR 2430 fits perfectly.

The CR 2025 apparently works much better if you place it concentrically into the lowering. I did not try this initially since I thought the back of the battery cover was not conductive.
   

Another question:

The calculator does not have parantheses on the keyboard. You rather use M+= and M-= to sum the results of products to the one and only memory register. You can retrieve and clear the result with the RM/CM key. Did many non RPN calculators use this technique at that time? From what I remember all TIs in my school used parantheses.

[Thomas Puettmann]

(01-27-2023 03:33 PM)Jeff_Birt Wrote:  It also seems the 3.2mm thickness of the above battery might be too much for your calculator.

I actually found a CR2032 in my basement. It has too much height. Maybe the 3 mm of the CR2430 will also be too much. So maybe the CR2025 is the correct battery and it is not a bug but a feature that there is some space around it.

Thanks again!

[Thomas Puettmann]

Ok, the battery problem is solved. Searching for "Knopfzelle LF-1/2W" leads to some pages that list "CR 2430" as an alternative name. Sorry, I should perhaps have tried to vary my search terms beforehand and make them more precise.