Re: Another Look at Alkaline vs. Rechargeable Batteries for HP-41 Message #7 Posted by Garth Wilson on 8 Nov 2005, 1:26 p.m., in response to message #6 by David Smith
So how much current does the card reader take, anyway? And how many seconds does it take to run a card through? One? According to my old Radio Shack battery guide book, running an ankaline N cell at 300mA (which I expect is considerably more than the card reader takes) for four minutes every hour, eight hours a day, with 16 hours' rest (enough for over 200 cards in those four minutes if I remember about how fast they go through, and if it really took 300mA),it should still last 70 minutes of the card reader motor actually running, or about 4000 card passes. I expect however that the card reader takes less than that amount of current, and that probably even the most dedicated user doesn't do 4000 card passes in a year, let alone in the self-discharge time of a rechargeable battery. Since you also can't keep feeding them non-stop for four minutes (or even a tenth of that time), there will be more recovery time between them.
I got the tape drive instead. Generally it was a much better solution, but I didn't like the fact that they made it unable to take regular alkaline batteries so I could leave it logging data remotely and automatically for a whole work day. The NiCads were only good for four hours on a charge if they were in new condition, whereas a set of alkalines could have gone a couple of days.
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