Re: Good grief! $56 for this part? Message #9 Posted by Ellis Easley on 25 Mar 2003, 8:55 a.m., in response to message #1 by Gene
That is an astonishing price but these have always been hard to get, apparently. In the PPC Journals there are discussions about battery life in the 41 which became a problem after the card reader was introduced. Users remarked that if HP would make the battery holder available as a spare part, things would be easier.
The high current requirement of the card reader motor makes alkaline batteries have a short effective life. After a relatively brief period of use there is plenty of energy to run the calculator but not enough to run the motor AND have sufficiently high output voltage to maintain the calculator memory. (I think the calculator intelligence takes over and refuses to operate the card reader when the battery voltage is below a certain level.) Using "N" NiCads in the regular battery holder was better for the card reader motor because NiCads maintain a fairly constant output voltage at high current drain compared to alkalines. But the NiCads will only run the calculator for a fairly short time because of their low capacity (150 mA-h vs >1000 mA-h for alkaline N cells) and their high self-discharge rate (need to be recharged once a month or so). This is aggravated by the fact that you can't recharge the cells in the calculator (Thank God! imagine how many 41's alive today wouldn't have survived if NiCads could have been recharged inside!) A good solution would be to have a spare battery pack loaded with NiCads so you could quickly change to NiCads when using the card reader. Apparently HP didn't make the spare battery holders available. Their solution was the rechargable pack which has even smaller capacity cells (I think 50 mA-h).
Another thing is that the springs are destroyed by battery leakage, leaving the plastic in fine shape. Somebody who used to advertise in the classified ads here had lots of the plastic holders without springs. I'd like to learn how to make those springs - what kind of wire to start with, etc. - because some of my holders have corroded springs.
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