HP Forum Archive 18

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HP-17B II financial calculator drains batteries frequently Message #1 Posted by Larry Gagnon on 11 May 2008, 3:49 p.m. Unfortunately I now rarely use my lovely HP-17B II business calculator because the batteries get drained too quickly and as they are cell button lithiums they are too expensive to keep replacing them all the time. Anyone else noticed this with the 17B II ? I suspect this is normal due to the inbuilt clock and alarm system of the 17BII but I could be wrong. Any suggestions other than keeping batteries out of the unit are appreciated. Edited: 11 May 2008, 3:52 p.m.

Re: HP-17B II financial calculator drains batteries frequently Message #2 Posted by Katie Wasserman on 11 May 2008, 4:20 p.m., in response to message #1 by Larry Gagnon The batteries should last for a least a couple of years with normal use. However one of my 32SII calculators (possibly of the same vintage as your 17BII) drains the batteries within 6 months. My guess is that this is due to high leakage currents within the chip itself, possibly all those chips cut form the same wafer during production. (I admit that this is a somewhat wild guess)

Re: HP-17B II financial calculator drains batteries frequently Message #3 Posted by Eric Smith on 12 May 2008, 1:31 a.m., in response to message #2 by Katie Wasserman If a CMOS chip has low leakage after manufacture, and the leakage suddenly goes up significantly at some later date, that's almost always a sign of ESD damage to the chip. When that's the cause, there's no fix other than replacing the chip. The only other obvious possibility is that the chip got into an unusual state. Remove the batteries and leave them out for a long time (weeks). If you're very lucky and the problem isn't ESD, that might fix it. But probably not.

Re: HP-17B II financial calculator drains batteries frequently Message #4 Posted by Ken Shaw on 12 May 2008, 8:35 a.m., in response to message #3 by Eric Smith I have the same experience with my 17BII (now about 10 years old). It consistently runs through batteries in about a year to 18 months. Sometimes they have lasted as little as 6 months. I've always assumed the cause to be the clock. There's a way to put the clock into hibernation, but you have to do it every time you turn the calc. off, so it's not practical for a daily use machine. See this thread http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv016.cgi?read=103729 Edited: 12 May 2008, 3:40 p.m.

Re: HP-17B II financial calculator drains batteries frequently Message #5 Posted by Larry Gagnon on 14 May 2008, 1:44 p.m., in response to message #4 by Ken Shaw Thank you exactly what I wanted. The trick is to put the calculator into an undocumented sleep mode which turns off the clock. The way to do it is turn off machine, press CLR + upper right ^ + lower right + all at the same time. Because I only use this calculator rarely this little trick should save me a lot of batteries - just need to remember to do it each time.

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