dimitrov@lab.ultra.nyu.edu (Isaac Dimitrovsky) (04/27/91)
[] My portfolio says alkaline batteries are recommended. Does anyone know if using Nicad rechargeables will actually cause problems, or if it just results in shorter times between battery replacement. Isaac Dimitrovsky
henry@zoo.toronto.edu (Henry Spencer) (04/28/91)
In article <1991Apr27.161015.19757@cmcl2.nyu.edu> dimitrov@lab.ultra.nyu.edu (Isaac Dimitrovsky) writes: >My portfolio says alkaline batteries are recommended. >Does anyone know if using Nicad rechargeables will actually >cause problems, or if it just results in shorter times >between battery replacement. You will have to recharge the nicads much more often than you will have to replace the alkalines, unless you are using your machine *a lot*. Nicads discharge themselves; they won't stay charged for more than a couple of weeks, typically. They really make sense only for high-power devices that would otherwise eat batteries like crazy. Most handhelds nowadays are sufficiently light on power that Nicads aren't worth it. I don't immediately see any problem they would cause, however. They do have somewhat lower output voltage than *fresh* ordinary batteries, but battery-powered hardware has to be able to run on nearly-dead batteries, and that means being able to cope with lower voltages. -- And the bean-counter replied, | Henry Spencer @ U of Toronto Zoology "beans are more important". | henry@zoo.toronto.edu utzoo!henry
ruhtra@turing.toronto.edu (Arthur Tateishi) (04/28/91)
In article <1991Apr28.012501.28554@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes: >In article <1991Apr27.161015.19757@cmcl2.nyu.edu> dimitrov@lab.ultra.nyu.edu (Isaac Dimitrovsky) writes: >>My portfolio says alkaline batteries are recommended. >>Does anyone know if using Nicad rechargeables will actually >>cause problems, or if it just results in shorter times >>between battery replacement. > >I don't immediately see any problem they would cause, however. They do The real problem with NiCd's is their power curve. Normal batteries follow a long steady line from 1.5V down. Nicads start at 1.2V, drop quickly to a level slightly lower and then suffer a very slow decline to ~1V or so. After that it just sort of drops away to nothing. Suddenly. This is really bad when your unit's memory could get wiped out. A computer's battery level alarm doesn't give a lot of warning and may not even trigger. BTW Henry, welcome aboard. In an earlier post you spoke of those right-shifted special characters. There is a nice keyboard template overlay you can buy. They should have included it with the base machine. -- Red Alert. -- Q, "Deja Q", stardate 43539.1 Arthur Tateishi g9ruhtra@zero.cdf.utoronto.edu
laird@think.com (Laird Popkin) (04/30/91)
In article <1991Apr28.012501.28554@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes: >In article <1991Apr27.161015.19757@cmcl2.nyu.edu> dimitrov@lab.ultra.nyu.edu (Isaac Dimitrovsky) writes: >>My portfolio says alkaline batteries are recommended. >>Does anyone know if using Nicad rechargeables will actually >>cause problems, or if it just results in shorter times >>between battery replacement. > >You will have to recharge the nicads much more often than you will have to >replace the alkalines, unless you are using your machine *a lot*. Nicads >discharge themselves; they won't stay charged for more than a couple of >weeks, typically. They really make sense only for high-power devices >that would otherwise eat batteries like crazy. Most handhelds nowadays >are sufficiently light on power that Nicads aren't worth it. > >I don't immediately see any problem they would cause, however. They do >have somewhat lower output voltage than *fresh* ordinary batteries, but >battery-powered hardware has to be able to run on nearly-dead batteries, >and that means being able to cope with lower voltages. One significant difference between NiCad batteries and ordinary batteries is the power curve as they go dead. Ordinary batteries deliver a gradually decreasing power level, whereas NiCad batteris deliver fairly level power and then go dead suddenly. What this means is that once you are warned that power is low, you have very little time remaining on the NiCad battery as compared to the regular battery. Given that a Portfolio will run on normal batteries for 2 months or so, I'd second Henry's advice not to bother with NiCads. - Laird Popkin
adrian@cs.hw.ac.uk (Adrian Hurt) (04/30/91)
In article <1991Apr28.012501.28554@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes: >In article <1991Apr27.161015.19757@cmcl2.nyu.edu> dimitrov@lab.ultra.nyu.edu (Isaac Dimitrovsky) writes: >>My portfolio says alkaline batteries are recommended. >>Does anyone know if using Nicad rechargeables will actually >>cause problems, or if it just results in shorter times >>between battery replacement. > >You will have to recharge the nicads much more often than you will have to >replace the alkalines, unless you are using your machine *a lot*. Nicads >discharge themselves; they won't stay charged for more than a couple of >weeks, typically. I have to disagree with that estimate of two weeks. My Psion Organiser runs off a PP3 sized NiCad battery, and it does so for around four weeks without a battery change. The battery in question will have spent a similar period charged but inactive, because my standard procedure is to carry a spare charged battery in a little belt pouch. That way, when the Organiser gives the "Battery low" warning, I can change its battery at once. I've been using the same pair of batteries for a few years now, and haven't lost any data to battery failure yet. Of course, the duration of a battery will depend on its size; and perhaps British batteries last longer than U.S. or Canadian ones. :-) As to the original question about using rechargeable batteries in a Portfolio: I'd expect that rechargeable would work. I doubt that the ability to use such batteries is a unique feature of the Organiser! As Henry said, though, rechargeables need changing more often than alkalines, so carry spares with you. "Keyboard? How quaint!" - M. Scott Adrian Hurt | JANET: adrian@uk.ac.hw.cs UUCP: ..!ukc!cs.hw.ac.uk!adrian | ARPA: adrian@cs.hw.ac.uk
darrylo@hpnmdla.hp.com (Darryl Okahata) (05/02/91)
In comp.sys.handhelds, henry@zoo.toronto.edu (Henry Spencer) writes: > I don't immediately see any problem they would cause, however. They do > have somewhat lower output voltage than *fresh* ordinary batteries, but > battery-powered hardware has to be able to run on nearly-dead batteries, > and that means being able to cope with lower voltages. Nicads could cause serious problems for those people who have been risking calculator damage by using a RAM card not designed for the HP 48SX (such as the Smith-Corona RAM cards, etc.). As the nicad battery voltages are lower, there's probably a bigger chance of the RAM card shorting out the calculator (when the RAM card detects a low battery condition, the RAM card clamps the address lines to *ground* -- which will do nasty things to the calculator if the calculator has not already detected a low battery condition and shut itself down before the RAM card does). BTW, I'd like to second your welcome here, Harry. -- Darryl ("We know who you are." ;-) Okahata UUCP: {hplabs!, hpcea!, hpfcla!} hpnmd!darrylo Internet: darrylo%hpnmd@relay.hp.com DISCLAIMER: this message is the author's personal opinion and does not constitute the support, opinion or policy of Hewlett-Packard or of the little green men that have been following him all day.
rzv30@cccvm.ccc.amdahl.com (Rene' A. Vega) (05/09/91)
I use rechargable batteries in my Portfolio. If I don't use it much, the batteries usually last a little over two weeks. If I use it a lot, They'll just make it a week. Other than the time I accidentally swapped in a pair of discharged batteries, I've not had problems. Rene' A. Vega Computer & Systems Architecture