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Very nice aaa battery pack for Classic Calculators
06-02-2016, 05:20 PM
Post: #1
Very nice aaa battery pack for Classic Calculators
Folks,

I've built very nice battery packs for the Classic Calculators that uses any AAA batteries. I'm offering at a discount to all HP Calculator Museum followers. I sell them for $25 + shipping on Ebay but will drop it to $18 and no shipping in USA (yet please add $12 additional international shipping). Please note attached picture.

Drop me an email waterhosko@aol.com if you'd like. Hope it's ok to send a note here?

Any tech feedback on using alkaline batteries in a generally lower voltage realm of rechargeable cells? I have not seen any problems with my calcs so far using alkaline, but I'm curious about the long-term effect of the initially higher voltage within these calculators?

Mark Hoskins


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06-02-2016, 08:00 PM (This post was last modified: 06-02-2016 08:01 PM by Massimo Gnerucci.)
Post: #2
RE: Very nice aaa battery pack for Classic Calculators
Hi Mark, this looks like a nice solution for classics.

I already found out your pack and mentioned it here...

Do you combine shipping charges for multiple orders?

Thank you very much!

Greetings,
    Massimo

-+×÷ ↔ left is right and right is wrong
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06-03-2016, 12:42 AM
Post: #3
RE: Very nice aaa battery pack for Classic Calculators
Yes I'd be glad to reduce costs for international shipping. Also if I send the cases with no cells I can even drop shipping costs more. Say $5 shipping.

I am still curious about the voltage issue. I have a friend who heard that alkalines will ruin the calculators. He does not know for sure this is true. I have measured voltages on charged battery packs over 4 volts. So I'm not at all convinced that alkalines will hurt the calculators.

Does anyone know for sure?

I have been running my calcs: HP-45 and HP-67 with no problems, on this case with AAA alkaline cells.
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06-03-2016, 09:54 AM
Post: #4
RE: Very nice aaa battery pack for Classic Calculators
Hello!

(06-03-2016 12:42 AM)Waterhosko Wrote:  Does anyone know for sure?

No, but I would rather ask: Why use alkaline batteries in the first place?

Rechargable 2500Ah NiMH batteries cost exactly the same as good alkalines and provide the voltage the calculator was designed for. The calculators can safely be used with it's charger when working at one's desk (try that with alkalines instead...). And, also import to some, one set of NiMHs outlasts 500 sets of disposable batteries.

Regards
Max
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06-03-2016, 12:31 PM
Post: #5
RE: Very nice aaa battery pack for Classic Calculators
(06-03-2016 09:54 AM)Maximilian Hohmann Wrote:  Rechargable 2500Ah NiMH batteries cost exactly the same as good alkalines and provide the voltage the calculator was designed for. The calculators can safely be used with it's charger when working at one's desk (try that with alkalines instead...).

As usual, I would not recommend the highest available capacity but Panasonic Eneloop NiMHs. They feature virtually no self-discharge so that they can be used even in calculators that you use only every few months.

The higher capacity compared to batteries of the Seventies yields a much lower relative charging current. This again means, with the original charger attached, harming the batteries by overcharging is nearly impossible. #-)

(06-03-2016 09:54 AM)Maximilian Hohmann Wrote:  And, also import to some, one set of NiMHs outlasts 500 sets of disposable batteries.

With an intelligent charger offering decent charge control, that is. I would not rely on this figure when using the "dumb" original HP chargers.

Dieter
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06-03-2016, 12:53 PM
Post: #6
RE: Very nice aaa battery pack for Classic Calculators
(06-03-2016 12:42 AM)Waterhosko Wrote:  I am still curious about the voltage issue. I have a friend who heard that alkalines will ruin the calculators. He does not know for sure this is true. I have measured voltages on charged battery packs over 4 volts.

Near the end of the charging process NiCds and NiMHs can and will reach voltages of 1,4 V per cell and more, in some cases even beyond 1,5 V. That's close to the output of a new Alkaline battery.

(06-03-2016 12:42 AM)Waterhosko Wrote:  So I'm not at all convinced that alkalines will hurt the calculators.
Does anyone know for sure?

Noone can say this for sure unless the electronic specification of the particular calculator is known. But this topic has been discussed here several times over the years. I only remember posts that say Alkalines are fine. After all, if a new Alkaline has 1,55 V and a fully charged NiMH 1,45 V, that's merely 7% difference. But again, I do not think there can be a definitive answer, unless...

Dieter
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06-03-2016, 02:51 PM
Post: #7
RE: Very nice aaa battery pack for Classic Calculators
(06-03-2016 12:42 AM)Waterhosko Wrote:  I am still curious about the voltage issue. I have a friend who heard that alkalines will ruin the calculators. He does not know for sure this is true.

IMHO, even NiZn rechargeable batteries (1.65 V) can't destroy calculator although still better to use low self-discharge nickel–metal hydride batteries (LSD NiMH) like Panasonic Eneloop 2100 (4th gen) with Smart Charger.
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08-08-2016, 10:31 PM
Post: #8
RE: Very nice aaa battery pack for Classic Calculators
I received this morning a AAA battery holder for the Classic & 75C/D/Pod series from Mark.
I had another one that I bought years ago from another vendor but it broke into pieces on the first drop.
This one is very sturdy, well made, easy to use, fit exactly the battery space and accept regular or rechargeable AAA.
The holder came with 3 NiCad AAA already charged in it.
Regards,
Sylvain
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