Calculator collection : How to power calcs without constantly opening?

[Jonathan Busby]

I have many calcs ( and several vintage small / handheld computers ) in my calculator collection. When I acquire a new item for my collection the first thing I do is take out the batteries so that they don't leak and ruin the item. The problem now is that to power up an item in my collection I have to open its battery compartment and insert batteries and then close it and then open the compartment again and take out the batteries and then close the compartment when I'm finished. This becomes tedious after a while and it also introduces wear and tear. I was wondering if anybody had thought of a solution to this. One idea I had would be to use an array of voltage regulators which supply power to a collection of DIY "dummy batteries". The problem is that the "dummy batteries" need a wired connection to the voltage regulators which would be provided via very thin shielded wire, but I'm not sure if said wire would break when the battery compartment is closed over it. Another idea I had would be to use DIY "dummy batteries" which are inductive receivers and use a small metallic plate as the inductive transmitter. I'm not sure how well this would work though or if it would adversely affect the calculator's operation.

Does anyone have any ideas or suggestions?

Regards,

Jonathan

[toml_12953]

(11-29-2021 05:34 PM)Jonathan Busby Wrote:  I have many calcs ( and several vintage small / handheld computers ) in my calculator collection. When I acquire a new item for my collection the first thing I do is take out the batteries so that they don't leak and ruin the item. The problem now is that to power up an item in my collection I have to open its battery compartment and insert batteries and then close it and then open the compartment again and take out the batteries and then close the compartment when I'm finished. This becomes tedious after a while and it also introduces wear and tear.

Does anyone have any ideas or suggestions?

Regards,

Jonathan

I don't take batteries out of any calculator I'm going to use within a few months. I only remove batteries for older, non-replaceable calculators of great value and mainly used for display. If you're planning on using a calculator every few weeks or months, then leave the batteries in. Just make sure they're not Duracell. HP issued a special warning about Duracells years ago. I don't know if the newer ones are more leak-proof but why take a chance?

[John Keith]

For the Voyagers which use 3 x SR44 cells it is safe to leave batteries in them for extended periods because silver oxide cells rarely leak. Just make sure they really are silver oxide type: the LR44 cells that also fit the Voyagers are alkaline cells which are not as leak-proof.

There are tales of batteries in voyagers lasting for decades, but I replace them every 3 years or so just to be safe.

For the Classics which use Ni-Cd cells the only safe option is to leave the battery packs outside of the calculator.

[StephenG1CMZ]

(11-29-2021 07:02 PM)toml_12953 Wrote:  

(11-29-2021 05:34 PM)Jonathan Busby Wrote:  I have many calcs ( and several vintage small / handheld computers ) in my calculator collection. When I acquire a new item for my collection the first thing I do is take out the batteries so that they don't leak and ruin the item. The problem now is that to power up an item in my collection I have to open its battery compartment and insert batteries and then close it and then open the compartment again and take out the batteries and then close the compartment when I'm finished. This becomes tedious after a while and it also introduces wear and tear.

Does anyone have any ideas or suggestions?

Regards,

Jonathan

I don't take batteries out of any calculator I'm going to use within a few months. I only remove batteries for older, non-replaceable calculators of great value and mainly used for display. If you're planning on using a calculator every few weeks or months, then leave the batteries in. Just make sure they're not Duracell. HP issued a special warning about Duracells years ago. I don't know if the newer ones are more leak-proof but why take a chance?

I wonder if you have a link about the Duracell batteries?
(I've always thought they were less likely to leak than many others).

[Hlib]

I don`t understand what the problem is. Connect the power to the contacts of the calculator, and replace the elements. Perhaps I don`t understand the nuances of your problem. In industrial electronics, I have never encountered more complex problems with power supply

[Dave Frederickson]

(11-29-2021 08:14 PM)StephenG1CMZ Wrote:  I wonder if you have a link about the Duracell batteries?
(I've always thought they were less likely to leak than many others).

I have a letter. Duracell reimbursed me $150 for the repair of my 71B.

https://drive.google.com/file/d/1TQGKmqp...sp=sharing

Dave

Edit: Duracell also included a new set of N-cells for my 71B. I tried to give them away but someone pointed out that they were leaking inside the package.

[Eric Rechlin]

The best thing is to buy lithium AA and AAA batteries for powering infrequently-used devices. They don't leak like alkalines and have a very long shelf life (rated for 20 years). I use the Energizer Ultimate Lithium brand. They are about US$1.25 each where I buy them at Home Depot, so about 5x the price of alkalines, but that's a small price to pay for the protection from leakage in something you use infrequently.

[Jonathan Busby]

(11-29-2021 08:38 PM)Hlib Wrote:  I don`t understand what the problem is. Connect the power to the contacts of the calculator, and replace the elements. Perhaps I don`t understand the nuances of your problem. In industrial electronics, I have never encountered more complex problems with power supply

The problem is that I want the battery doors / compartments *closed* and that may well sever small insulated wire.

Regards,

Jonathan

[Jonathan Busby]

(11-29-2021 07:02 PM)toml_12953 Wrote:  I don't take batteries out of any calculator I'm going to use within a few months. I only remove batteries for older, non-replaceable calculators of great value and mainly used for display. If you're planning on using a calculator every few weeks or months, then leave the batteries in. Just make sure they're not Duracell. HP issued a special warning about Duracells years ago. I don't know if the newer ones are more leak-proof but why take a chance?

I didn't know about the problem with Durcells -- I have three AAA Duracells in one of my HP48GXs. Perhaps I should replace them with Energizers?

Regards,

Jonathan

[John Keith]

Lithium AA and AAA cells do have a higher voltage than alkaline cells, about 1.7V no load. Probably not a big deal but I've always been hesitant about using them with older electronics.

[mfleming]

(11-29-2021 08:54 PM)Dave Frederickson Wrote:  I have a letter. Duracell reimbursed me $150 for the repair of my 71B.

https://drive.google.com/file/d/1TQGKmqp...sp=sharing

Dave

Dave, there's nothing in the letter that specifically warns against use of Duracell batteries, just a list of three battery manufacturers and how to contact them for possible damage reimbursement. Which Duracell did. How old is the letter?

Don't want to stir back up the Duracell bites/Energizer bites controversy!

[Eric Rechlin]

(11-29-2021 09:45 PM)John Keith Wrote:  Lithium AA and AAA cells do have a higher voltage than alkaline cells, about 1.7V no load. Probably not a big deal but I've always been hesitant about using them with older electronics.

I measure the lithiums at 1.65 V and fresh alkalines at 1.59 V so there isn't much of a difference. But yes, if something is particularly sensitive it is worth noting the slight increase in voltage.

[agarza]

I remove the batteries.

[SammysHP]

If there's enough space on the battery compartment, you could try a voltage regulator and a wireless charging sticker.

[Nihotte(lma)]

(11-29-2021 05:34 PM)Jonathan Busby Wrote:  I have many calcs ( and several vintage small / handheld computers ) in my calculator collection. ...

Does anyone have any ideas or suggestions?

Regards,

Jonathan

Hi all,

I usually don't remove the batteries from my calcs because I like to use them regularly. But I put a little adhesive part of a post-it on the back of the calculators and I document by this way the recommended month in mm/yyyy format to remove and change the batteries when it's time to do it.
In an other way, you can established a list of the calcs on paper (smartphone,...) and link each serial numbers or models with a limit remove date of the batteries.

Keep you safe !

Laurent

[Jonathan Busby]

(11-30-2021 05:33 AM)SammysHP Wrote:  If there's enough space on the battery compartment, you could try a voltage regulator and a wireless charging sticker.

Thanks for the suggestion

Regards,

Jonathan

[Dave Frederickson]

(11-30-2021 12:12 AM)mfleming Wrote:  

(11-29-2021 08:54 PM)Dave Frederickson Wrote:  I have a letter. Duracell reimbursed me $150 for the repair of my 71B.

https://drive.google.com/file/d/1TQGKmqp...sp=sharing

Dave

Dave, there's nothing in the letter that specifically warns against use of Duracell batteries, just a list of three battery manufacturers and how to contact them for possible damage reimbursement. Which Duracell did. How old is the letter?

Don't want to stir back up the Duracell bites/Energizer bites controversy!

It's from April 1987.

[EugeneNine]

I've had more Rayovac's leak than any other AA, then Energizer and then Duracell. Manufacturing lines change from time to time so the battery you buy today isn't the same as the one you bought a decade ago.
But what I've done is invested in Eneloops and schedule a annual/bi-annual swap and charge. Rechargeable NiMH are less prone to leaking (but still possible) and Eneloops have remained the highest rated since their introduction and seem to be the safest bet still.

For other voltages though the idea of a small Lithium Ion pack coupled with wireless charger would make a decent alternative. Most of the problems with lithium ion are due to device manufactures pushing them to 110% of their design to make the device charge as fast as possible and run as long as possible between charges (and wear the battery out as fast as possible in order to sell a new one, so if you charge them slower and set the charge to stop at less than 100% with a small charging ic that allows for specifying charge parameters you can make them very reliable.

Another option is to 3dprint replacement battery doors so you put the original away somewhere and use the 3dprinted clone. Make your clone door fit a little more loose so it doesn't wear out latches and such.

[mfleming]

(12-01-2021 02:18 AM)EugeneNine Wrote:  I've had more Rayovac's leak than any other AA, then Energizer and then Duracell. Manufacturing lines change from time to time so the battery you buy today isn't the same as the one you bought a decade ago.

Well known brands should have their manufacturing process down pat so you would only get the occasional tail of the distribution. I've had a couple of Energizers leak, but only because I buy far more of them than Duracells. Relabeled house brands (hardware store, grocery store) always seem to leak!

[Ren]

Duracells have gotten worse since Procter and Gamble bought them out.
They have milked the "reliability" cow dry, while making the batteries cheaper.

edit: Ikea actually had good batteries (both rechargeable and disposable), but they closed them out last year in a misguided effort to be "green".