Calculator with insane 37-year battery life - Page 1
Forum section: electronics / general

author: JohnnyMalaria
author_rank: Super Contributor
timestamp: May 11, 2018, 02:41:43 am
content: This is my Casio fx-3600P scientific calculator that I bought in 1981 when studying for my O-levels. I still use it today. It's my go-to and beats my phone's scientific calculator app hands down. And it is stilling running on its original batteryBased on the power consumption and capacity of a CR2025 3V cell, the lifetime should be about 1000 hours.Is this a record? What's the longest battery life you've experienced for something actually in use, of course?(OK, I tried twice to rotate these...MS Paint saved the day)

author: Rerouter
author_rank: Super Contributor
timestamp: May 11, 2018, 03:32:55 am
content: the self discharge rate of a coin cell battery is a specification with a fairly wide distribution.Longest lasting battery I have seen in the wild was the realtime clock battery in a 1982 spectrum analyser, the power supply cooked the CRT last year, but when i pulled it out, that battery was still at 2.9V (didnt check the ESR)

author: Nusa
author_rank: Super Contributor
timestamp: May 11, 2018, 04:50:18 am
content: My original model FX-115 scientific calculator still works. Of course it never needed a battery, being solar-only. Not sure exactly when I bought it, but I know it was prior to 1985.

author: Rick Law
author_rank: Super Contributor
timestamp: May 11, 2018, 05:09:04 am
content: Wow, 37 years. You got me beat.I last opened the battery compartment of my HP16C was before 1986 putting batteries in for the first time. I am still using that same set of battery since then -- 31 years ago.I used it daily for a year or two, then perhaps a hour or so weekly/biweekly for the last 31 years.

author: Synthtech
author_rank: Regular Contributor
timestamp: May 11, 2018, 08:48:53 am
content: I regularly have Roland synthesisers from the 80’s coming into my workshop for repair with lithium backup batteries showing 3.2V. They picked a good brand, Panasonic from memory.

author: Emo
author_rank: Regular Contributor
timestamp: May 11, 2018, 09:53:46 am
content: Yes, same here. The original long life casio batteries still doing OK.Bought it 88/89

author: Electro Detective
author_rank: Super Contributor
timestamp: May 11, 2018, 10:14:04 am
content: The power draw at 3 volts is specified as 0.00043WI reckon the battery is way past its 'Use By Date...' but chemically sound and keeps kicking back to life just enough to power that CasioEither that, or the battery has spilled its goods all over the board, powering the components directly ()

author: Rerouter
author_rank: Super Contributor
timestamp: May 11, 2018, 10:25:21 am
content: On the flip side, mercedes cars from 1987-1992 sometimes had a battery backed up service computer, If its not been replaced by now, your $400 instrument cluster is mostly a leakage horror story by now.

author: Deridex
author_rank: Regular Contributor
timestamp: May 11, 2018, 05:12:37 pm
content: This Battery Lifetime is highly impressive.At the stuff i work at the longest batterylifetime i remember so far is about 10 years or so.

author: glarsson
author_rank: Frequent Contributor
timestamp: May 11, 2018, 05:50:15 pm
content: I have an old Minolta SRT101 SLR camera with a mercury battery, PX625, that still works. The battery was installed sometime before 1980, at the time when the camera was in active use. The camera has, obviously, not been used for many years, but the battery check still says the battery is ok.

author: JimRemington
author_rank: Regular Contributor
timestamp: May 11, 2018, 05:56:16 pm
content: Bought my HP-11c in 1985, and changed the (still good) 3 button cells two years ago, so that the calculator would not be ruined by battery leakage

author: SeanB
author_rank: Super Contributor
timestamp: May 11, 2018, 07:36:19 pm
content: Saft and Crompton eternacell primary lithium cells are well known for long life. Have a Crompton eternacell that, while the ESR is in the kilohm range, and it is around 150 years past the 15 year shelf life, it still has an open circuit voltage of 3V7, and which was running a chime mechanism for around 5 years as power source. Only reason it was retired was the ultra high ESR, it would droop in voltage driving the hourly chime, despite having a good big 22000uF of capacitance acting as a voltage buffer for the power, it was just no longer able to keep the clock oscillator for the chime board stable. Was a cheap purchase from the local Maplin subsidary after they had gone independant, and they were selling off them really cheap as they were at end of storage life.My calculator is a Casio FX602P, which does have a very long battery life, running on 2 CR2032 cells. Originals lasted around a decade after I got it, and since then it has had 2 changes of them, just as preventative maintenance. Got it for school use many years ago, and it is still used every so often.

author: precaud
author_rank: Frequent Contributor
timestamp: May 12, 2018, 12:43:37 pm
content: I parted out an old HP 1980B scope (mid-80's vintage) last week. It uses a 3V 2/3-AA lithium cell to power its NV ram, and its a bit of a pain to get to, buried deep in the vertical amps' module. Sure looked like the original battery, a Panasonic. To my surprise it measured 3.1V ! That's over 30 years old.

author: frozenfrogz
author_rank: Frequent Contributor
timestamp: May 12, 2018, 01:23:07 pm
content: Quote from: Nusa on May 11, 2018, 04:50:18 amIt is solar powered, but there is also a small cell inside. Had to change the one on mine some time ago. It now has a new home in South Africa @HecticZAs place

author: Nusa
author_rank: Super Contributor
timestamp: May 12, 2018, 02:38:33 pm
content: Quote from: frozenfrogz on May 12, 2018, 01:23:07 pmNegative. The later "c-power" model (115M) and similar versions (115N) also had an internal cell. The original 115 really was solar only.

author: bd139
author_rank: Super Contributor
timestamp: May 12, 2018, 05:32:55 pm
content: I had a Casio Fx115 circa 1986. Buttons gave out in 2009 before the battery did.

author: frozenfrogz
author_rank: Frequent Contributor
timestamp: May 12, 2018, 07:10:12 pm
content: Quote from: Nusa on May 12, 2018, 02:38:33 pmOh, I see. Now that you mention it, mine was the "s" model. Did not know there were various makes through the years. I always thought s meant solar. xDThe original 115 looks nice with the aluminium cover and black/gray/yellow button theme.My EDC calculator has been an HP 16C for some time now.

author: richnormand
author_rank: Unknown
timestamp: May 12, 2018, 08:24:08 pm
content: OK, I'll take your 37 years battery lifetime and raise you one:Oxford bell battery working since 1840...https://en.wikipedia.org/wiki/Oxford_Electric_BellSeriously, I would take the cover off the calculator and make sure the battery is not leaking though.

author: JohnnyMalaria
author_rank: Super Contributor
timestamp: May 12, 2018, 09:22:28 pm
content: Quote from: richnormand on May 12, 2018, 08:24:08 pmWow. I think I prefer the other name for itQuoteI did - it's squeaky clean.

author: richnormand
author_rank: Unknown
timestamp: May 12, 2018, 10:33:44 pm
content: Quote""Seriously, I would take the cover off the calculator and make sure the battery is not leaking though.I did - it's squeaky clean.""Great. I would not dare doing a battery test that could kill it. Hope you keep us postedCheers.

author: labjr
author_rank: Frequent Contributor
timestamp: May 12, 2018, 10:59:27 pm
content: I used this calculator when I worked at DEC in 1985. Still has the original batteries. Probably because it's "Made in Japan". Batteries probably are too.