sjk@ut-emx (bob) (09/05/90)
Netters, I have a question regarding an old HP calculator called the 41CX; perhaps you remember it. Anyway, I am running it with the rechargeable battery pack, but am always left guessing when it needs recharging (or I wait till it beeps, then quit whatever I'm doing to set up the recharge.) Is there any way I can find out how much charge is left, so I can recharge it when it's low, but not yet to the state where it'll beep at me? Thanks, Scot sjk@astro.as.utexas.edu
lennartb@lne.kth.se (Lennart Boerjeson @ KTH/LNE, The Royal Inst. of Tech.) (09/12/90)
In article <36930@ut-emx>, sjk@ut-emx (bob) writes: > > > >Netters, >I have a question regarding an old HP calculator called the 41CX; >perhaps you remember it. Anyway, I am running it with the >rechargeable battery pack, but am always left guessing when it >needs recharging (or I wait till it beeps, then quit whatever I'm >doing to set up the recharge.) Is there any way I can find out how >much charge is left, so I can recharge it when it's low, but not >yet to the state where it'll beep at me? > >Thanks, > >Scot >sjk@astro.as.utexas.edu No way. The only sensor available to you is the low battery indicator (if I remember correctly you can sense it via a system flag). Why do use rechargeable batteries? Do you use a card reader *extensively*? I replaced my Ni-Cad pack with ordinary alkalii batteries when I stopped using my card reader. MUCH longer life. If you have an old 41 which still has the connector for the never-released battery eliminator you can save battery life by using a home-built, external battery pack at home. !++ ! Lennart Boerjeson, System Manager ! School of Electrical Engineering ! Royal Institute of Technology ! S-100 44 Stockholm, Sweden ! tel: int+46-8-7907814 ! Internet: lennartb@lne.kth.se !--
rrd@hpfinote.HP.COM (Ray Depew x2419) (09/12/90)
>I have a question regarding an old HP calculator called the 41CX; >doing to set up the recharge.) Is there any way I can find out how >much charge is left, so I can recharge it when it's low, but not >yet to the state where it'll beep at me? Well, I've still got my 41CX, but I gave away the manuals and Wlodek's masterpiece a while ago, so .... There is a "Low Battery" system flag on the 41. It can be tested, but not set or cleared (by normal means, anyway). I think (corrections, please) that one system routine monitors the battery and sets the flag, while another routine monitors the flag status and turns on the BAT annunciator and/or the "LOW BATTERY" message. Unfortunately, the battery check on the 41 is a binary check: either it's low or it isn't. (Comparators are not as complicated as ADC's, I guess.) Fortunately, when the annunciator comes on you still have plenty of runtime before you're REALLY in trouble. >Thanks, >Scot Not what you wanted to hear, but you're welcome anyway. Regards Ray Depew HP Colorado IC Division rrd@hpfitst1.hp.com Just me shooting off my mouth....
mark@hpcpbla.HP.COM (Mark Simms) (09/19/90)
The problem with the low battery indicator on the HP-41 series calculators is that it does not work well with NiCads. These, by their very nature, have a very stable voltage over most of their life and then fail very quickly. As such the low battery indication is signaled with less useful life in the batteries than with alkaline cells. It is still better than nothing. The most important thing is that you can plug in the recharger and recharge the batteries whilst the calculator is running and without removing the batteries. This is particularly important for Time Module users who don't want to reset their clocks. As for using alkaline cells, the NiCads are much cheaper in the long run and do not waste raw materials. They also cause considerably less polution. For users in the U.K. where N size cells are nearly impossible to get hold of, NiCads are a must. Mark Simms ---------------------------------------------------------------------- Opinions expressed are my own and are not intended to be an official statement by Hewlett-Packard Company ---------------------------------------------------------------------- Name: Mark Simms Profession: Software Engineer Occupation: Research and Development Organization: Hewlett-Packard Computer Peripherals Division Unix-mail: mark%hpcpbla@hplb.hpl.hp.com Address: Filton Road, Bristol BS12 6QZ, United Kingdom Phone: +44-272-799910x22174 Fax: +44-272-236091 ----------------------------------------------------------------------
akcs.michaelv@hpcvbbs.UUCP (Michael VanLoon) (10/19/90)
The low power flag is #49. The solution I found for dying NiCd's is to have a set of alkaline N-cells handy for the "moment of truth" when the BAT annunciator comes on. Simply pop the alkalines in to get you through the moment, until you can get home and recharge. Then stick the alkalines back in a safe spot until next time. Alkaline batteries have a shelf life of several years, so this should work well for many drain/recharge cycles. (I'm still using the original alkalines that came with my 41CX 2-1/2 years ago for this purpose with no problems). Michael V ISU