Lithium (coin cell) backup battery

[SEasterling]

Does anyone know the first graphing calculator model in which a lithium (coin cell) backup battery was used? I thought I saw it in a 48G+, but maybe I was seeing things through keto brain fog. Thanks!

Edited to specify lithium coin cell battery.

[ijabbott]

(11-20-2021 02:53 AM)SEasterling Wrote:  Does anyone know the first graphing calculator model in which a lithium ion backup battery was used? I thought I saw it in a 48G+, but maybe I was seeing things through keto brain fog. Thanks!

Perhaps the TI-81, but some early TI-81 units omitted the backup battery, according to Wikipedia.

[Maximilian Hohmann]

Hello!

Sorry to be nitpicking, but "lithium ion" batteries are rechargeable batteries that were first introduced to the market in 1991 by Sony (although the invention by Nobel price winner John B. Goodenough dates back to 1979).
Therefore there can be no (commercially available) calculator with a Lithium ion battery before 1991.

But I guess that you mean the non-rechargeable lithium based coin cells (mostly lithium manganese oxide). I don't have all the Sharp and Casio calculators in my collection but the Casio PB700 from 1983 already uses a CR-1220 lihium battery for memory backup. And I am very sure that there must be older ones.

Regards
Max

[Liam Hays]

(11-20-2021 02:53 AM)SEasterling Wrote:  Does anyone know the first graphing calculator model in which a lithium ion backup battery was used? I thought I saw it in a 48G+, but maybe I was seeing things through keto brain fog. Thanks!

If you mean a lithium coin cell, like Maximilian Hohmann suggested, the 48G+ was definitely not the first to use one. None of the 48 series use any backup battery, instead, the memory is held by a capacitor that is only discharged when the main AAAs are removed.

That said, I am reasonably sure that the 49 series and the 50 use a backup. Don't quote me on that, though, as I don't own them.

[Jonathan Busby]

I know of no HP calculator* ( unless you consider the HP 100LX/200LX calculators ) that uses a backup battery. As has already been mentioned a capacitor is used to supply voltage to the SRAM when the batteries are being changed.

On another note, if you use lithium based non-rechargeable batteries ( eg. Energizer Ultimate Lithium AAAs ) be aware that when the batteries are almost fully discharged and you get a low battery warning you need to replace the batteries ASAP because unlike regular alkaline batteries lithium-based batteries tend to drop to almost 0 volts when a load is applied when they're almost dead. Take it from me : I've been bitten by this behavior several times and have consequently lost my calc's memory.

Regards,

Jonathan

* At least Saturn based...

[SEasterling]

Thanks for the replies and sorry for my ignorance using the battery type too loosely. I should have specified lithium coin cell (3V, 2032) and was inquiring exclusively to HP graphing calculators. (I didn’t realize there was a large TI following here since it’s been a long time since I was active on this forum.). But specifically, I was wondering if HP had ever used a “lithium coin cell” for memory backup on any of the 48 series models (e.g., 48G+ or late-production 48GX) before discontinuing production in Indonesia. I know that my 49G+ and 50G models have this extra battery, but didn’t know if HP started doing it on the 48 just prior to ending that series. I know that none of the 48S, SX, G, G+, or GX models I’ve owned didn’t have them, but I may not have had late production models. Thanks.

Bonus tangent question: Tipping the hat to the Sparcom expansion cards available back in the day, it was a good time to be a student or working professional. I have used a 28S and never could afford the SX or GX at the time so I never actually used those Sparcom math, chemistry, physics, etc cards. For those that did, how would they compare to the 50G and Prime models now? Is the Sparcom info built into the latter models?

Thanks!

[Jonathan Busby]

(11-20-2021 06:26 PM)SEasterling Wrote:  Thanks for the replies and sorry for my ignorance using the battery type too loosely. I should have specified lithium coin cell (3V, 2032) and was inquiring exclusively to HP graphing calculators. (I didn’t realize there was a large TI following here since it’s been a long time since I was active on this forum.). But specifically, I was wondering if HP had ever used a “lithium coin cell” for memory backup on any of the 48 series models (e.g., 48G+ or late-production 48GX) before discontinuing production in Indonesia. I know that my 49G+ and 50G models have this extra battery, but didn’t know if HP started doing it on the 48 just prior to ending that series. I know that none of the 48S, SX, G, G+, or GX models I’ve owned didn’t have them, but I may not have had late production models. Thanks.

To the best of my knowledge, none of the Saturn-based S/SX or G/GX models ever used a backup battery, instead, they used a capacitor to maintain the SRAM contents when changing the batteries.

Regards,

Jonathan

[rprosperi]

Among HP's graphing models, the first to use a coin cell backup battery were the 49g+ and 48gII in Oct 2003. The "HP-48gII" would appear to be a 48, but in fact it's really a 49g+(-) and not a 48 at all. The 39g+ followed a few months later and then the 39gs/40gs/50g a couple years later.

Among non-graphing models, many of the late, low-end models which use 2 x CR-2032 batteries can be considered to also use coin cells as a backup battery as they will actually run with only 1 battery installed, so the idea of having 2 is to have longer life between battery change, and then you install new batteries one at-a-time so the other battery is a backup for the one you're changing.

[SEasterling]

Thanks, Bob, for the clarification. I normally always change one battery at a time for any electronic device that might have memory that needs to be retained.

Any comments on my tangent question?

[ijabbott]

(11-20-2021 08:51 PM)SEasterling Wrote:  Any comments on my tangent question?

If you count MetaKernel as a Sparcom / da Vinci product, then most of it ended up in the 49g+.

Side note: Their EE*Pro and ME*Pro products were ported to the TI-92 Plus, Voyage 200, TI-89, and TI-89 Titanium.

[rprosperi]

(11-20-2021 09:54 PM)ijabbott Wrote:  

(11-20-2021 08:51 PM)SEasterling Wrote:  Any comments on my tangent question?

If you count MetaKernel as a Sparcom / da Vinci product, then most of it ended up in the 49g+.

Side note: Their EE*Pro and ME*Pro products were ported to the TI-92 Plus, Voyage 200, TI-89, and TI-89 Titanium.

Well, I guess you can call mk a Sparcom product, but not really, if you know what I mean...

Other than that, no, none of the other Sparcom applications were ever included in subsequent machines, but they were all probably too deep into application areas for inclusion in the mainframe, and too complex to just throw into a free add-on library, and all to say nothing of the complexities and cost of licensing 3rd party s/w, which HP only did very rarely (with mk being a hugely important exception).

[toml_12953]

(11-20-2021 05:46 PM)Jonathan Busby Wrote:  I know of no HP calculator*
Regards,

Jonathan

* At least Saturn based...

Is the 50g ARM-based? It uses a backup battery.

[SEasterling]

How good were the math, physics, and chemistry plug-in cards from Sparcom? We’re they only good for first-year physics and math, or we’re they actually helpful for E/M and ODE problems? I’m thinking that the 50G and Prime with CAS are better than a 48GX with every card made, correct?

[ijabbott]

(11-20-2021 11:19 PM)rprosperi Wrote:  

(11-20-2021 09:54 PM)ijabbott Wrote:  If you count MetaKernel as a Sparcom / da Vinci product, then most of it ended up in the 49g+.

Well, I guess you can call mk a Sparcom product, but not really, if you know what I mean...

More in a distributor role for the project.

[EugeneNine]

Wasn't used directly in the calculator, but some of the ram expansion cards for the SX had a coin cell. So it was technically used by hp then,.

[Jonathan Busby]

(11-20-2021 06:39 PM)Jonathan Busby Wrote:  

(11-20-2021 06:26 PM)SEasterling Wrote:  Thanks for the replies and sorry for my ignorance using the battery type too loosely. I should have specified lithium coin cell (3V, 2032) and was inquiring exclusively to HP graphing calculators. (I didn’t realize there was a large TI following here since it’s been a long time since I was active on this forum.). But specifically, I was wondering if HP had ever used a “lithium coin cell” for memory backup on any of the 48 series models (e.g., 48G+ or late-production 48GX) before discontinuing production in Indonesia. I know that my 49G+ and 50G models have this extra battery, but didn’t know if HP started doing it on the 48 just prior to ending that series. I know that none of the 48S, SX, G, G+, or GX models I’ve owned didn’t have them, but I may not have had late production models. Thanks.

To the best of my knowledge, none of the Saturn-based S/SX or G/GX models ever used a backup battery, instead, they used a capacitor to maintain the SRAM contents when changing the batteries.

Regards,

Jonathan

I own a late production Indonesian HP48GX and it has no backup battery. I bought it around 2003 from Fry's just before HP discontinued the HP48G series. Seeing that HP had no intention of continuing production of their Saturn-based calcs, it would have been illogical for them to spend money to rework the PCB and case for a backup battery. Reworking the PCB wouldn't have been a big deal technically but there's the problem of really no more pins available on the Yorke SoC to detect a backup battery low battery condition. Reworking the case would have been harder to allow the user to change the battery -- HP really had no incentive to do this as they were discontinuing their Saturn-based calcs.

Regards,

Jonathan

[Jonathan Busby]

(11-21-2021 04:10 AM)toml_12953 Wrote:  

(11-20-2021 05:46 PM)Jonathan Busby Wrote:  I know of no HP calculator*
Regards,

Jonathan

* At least Saturn based...

Is the 50g ARM-based? It uses a backup battery.

Yes. Aside from the first successor to the 48G series, the 49G, all the subsequent HP calcs that succeeded the 49G onward were ARM-based.

Regards,

Jonathan

[Jonathan Busby]

(11-21-2021 05:23 PM)EugeneNine Wrote:  Wasn't used directly in the calculator, but some of the ram expansion cards for the SX had a coin cell. So it was technically used by hp then,.

Yes, but all the SRAM-based memory expansion cards for the SX and GX use some type of lithium coin cell battery and that battery was only used to preserve the contents of the card's SRAM memory when they were removed from the calculator or the calculator was turned off ( The Clarke and Yorke based calcs supplied power to RAM cards when they were on but not when they were turned off ). The card's battery had nothing to do with the preservation of the calculator's internal RAM, which, as has already been mentioned, was preserved by a capacitor when the main batteries were being changed.

Regards,

Jonathan