I went to college in the mid-to-late 1980s. At some point, I bought a good scientific calculator, an HP 15c. I’m sure I used it in some classes back then, but didn’t have much need for it after graduating. I remember using it sometimes when doing my taxes, or other tasks, but it probably sat in a drawer for years at a time, too.
Recently, I started a project that requires a lot of calculations. Last night, the display indicated that the batteries were getting low. I was away from home, so I looked up the owner’s handbook online, found what kind of batteries it needed, and picked them up on my way home. I replaced the batteries, turned it on, and it works fine.
The thing is, I can’t remember ever putting new batteries in it before. It takes 3 A76 or LR44 (alkaline) or 357 (silver oxide) batteries. The ones I took out were alkaline, which is what the calculator came with when new (according to the handbook), so they may be the originals. The book also says that they should last at least 1.5 years if he calculator isn’t used.
Is it really possible that I got more than 30 years of (very intermittent) use from a single set of batteries?
I was looking for markings to see if there was any indication who made them, or if they were really that old. It looks like “LR44 MADE IN JAPAN MMBC 6”.
I have a Texas Instruments scientific calculator from 1990 and I know for a fact the batteries have never been changed. You’d need a tool to remove four very small screws, which I’ve never done. I tried it just now for the first time in over a year and it still works. Pretty amazing.
I have a calculator that I got in 1976 (it must have been an expensive gift at the time from my folks (it does exponentation and fractions)); I misplaced it for several decades - but the batteries are still good
When my dad had a pacemaker installed, I asked the doc “how do the batteries get replaced if it’s surgically implanted in his chest?” The doc told me, which I was surprised to find out, that pacemaker batteries last on average 12 to 15 years. “So we’ll revisit things down the road when the batteries are getting close to running out”.
The unspoken subtext, of course, being, “if he’s still alive by then”. My guess is that the great majority of pacemaker batteries have no need of replacement.
I’ve heard that devices which have a manual on/off switch will use no power when off, while those with a button (like the 15c) will have a slight trickle of power to know when the button has been activated. I would have expected the 15c to trickle down the battery while off over that time since it has a soft button for power. Perhaps that calculator has some aspect to the power button to where it doesn’t need a trickle of power in order to activate the button, in which case it works more like a manual on/off switch.
I have a 12c which I use from time-to-time. My batteries last a really long time, but not forever. I remember one specific time when they ran out. It was back when taxes had to be mailed in. I was doing them at the last minute and the calculator wouldn’t power on. Rather than use a different calculator, I went to the store to get new batteries for it because I prefer the RPN way it has to do the math.
The 15c keeps things in memory when it’s turned off. This was in the '80s, before flash drives were common. The instructions for changing the batteries say there’s a risk of the memory being erased during the process, so I suspect there was some current flowing. Plus, it turns off by itself when it isn’t used for a few minutes, so it’s not a pure hardware on/off switch.
When I first tried an RPN calculator, I wasn’t a big fan. It seemed non-intuitive after using a conventional calculator. It didn’t take long for me to learn to love it. Now I’m worried it might break someday and I won’t be able to replace it. It’s great for the vector mechanics equations I’m using it for now.
My group of friends was geeky enough (at an engineering school) that we attempted to compare the speed of calculation on an HP RPN calculator vs a Texas Instruments algebraic calculator. As I remember, the RPN calculator was indeed faster. (Though the HP 15c I bought in 1986 or so cost something like $200 at the time, which was a huge splurge for me as a college student.)
I lost all the custom programming in my HP-41CX due to that, programming for calculating rise/run/slope, being able to enter in feet/inches/16ths, it was heartbreaking.
I was wondering about this yesterday and had planned to ask the dopers for their help. But this thread may answer my question. We have a bathroom scale that shows digits when you step on it. It doesn’t get stepped on more than about once or twice every couple weeks. And of course, we step off after about 10 seconds of use. But we’ve had this thing for at least 20 years and I don’t even have a clue about where the batteries are. It will probably last longer than we will.
I never use a calculator for anything serious any more because I’m almost always in front of a computer at any time I need to calculate anything much, and a spreadsheet is so much better than a calculator.
Almost every time I use a calculator now when I could have used a spreadsheet I regret it - despite the best of intentions, I always end up having to revisit the calculations. On a calculator this means re-doing them. On a spreadsheet, they are still right there in front of you.
I follow a couple of youtubers who tear down and/or fix old electronics. It is remarkable how often 30 year old things still work with the original batteries, if they were either alkaline or nicads (particularly the latter).
I bought an HP 15c in 2011 when they re-released it. (I paid $99.99 plus shipping and sales tax, and going through old emails, I ordered it in September but didn’t receive it until late December.
There are faithful emulators for many HP calculators for smartphones. I use an HP-25 emulator on my iPhone. I got so used to using the physical one when I was a student that my fingers still know where to go on the emulated keyboard.
The emulation even performs a little haptic click on each key press.
I still have the real one in a draw. But those machines used Ni-Cad batteries which have long since died. It is possible to rebuild the battery packs but it involves physical violence and I’m happy using the emulator.
Today, I used my digital calipers which are 14 years old and still measure perfectly. They are powered by a single LR44 cell like those found in some calculators. I am 100% certain I have never changed it because the calipers came with a spare cell, which is still in the storage slot. Why the product designer thought a spare would be essential when the installed cell lasts approximately forever, I will never understand.
