Sting curiosity


ciao a tutti,

pure curiosity...

Has ever existed an external battery charger for the

HP10 and HP19C ??

Take care Alberto


Hi Alberto,

I've asked the same question before, and the answer is no.



ciao Katie, thanks for the reply

That's too bad,

I'm thinking about adapting a HP91/92/97 power pack

To me,it should make sense, both batteries packs have the same

voltage output although maH capacity is different.

Even the width of the power pack should be make possibile to host the

Sting battery pack

What do you think ? Waste of time or it might work ?


Alberto, I've modified all of my Sting packs by cutting out the two cross-bars on the front side and gluing in three sets of double springs to allow me to place regular AA rechargeable batteries into the packs. You can then easily charge the batteries in a regular charger. This eliminates the danger of trying to charge the pack in the calculator. With the newer NiMH batteries that hold their charge for up to a year, I've had no problems at all. Just a thought.


That is a good idea. From a comment in another thread, isn't the danger to the calculator "eliminated" if you only charge in the calculator, never turning it on when it is plugged in? I just bought a 19c, so I'm trying to figure out what I want to do.



Well, it is probably only totally safe to charge a battery in a Woodstock/Sting calculator w/o continuous memory, because even with the calculator switched off, power is still being delivered to continuous (CMOS) memory. Any calculator with the "C" suffix in the model number (25c, 29c, 19c) has continuous memory.


ciao Michael,

that's a good idea, no doubt about it.

This said, let me tell you that I do belong to the category of collectors that will not use his toys(*)
I'm trying to keep them as much as possible close to the original look, which is why I have recelled my pacs and I wish I can avoid the modification.

Considering that even the power supply has the same voltage output
for both Topcat and Sting, I think it should work.

It's more the pleasure of making it that the real need ....

(*) not really true, this is my idea of using the collected items :

1st unit : definetely collection item, not for use

2nd unit of the same model : backup of the collection, not for use

3rd unit of the same model : you never know, may be you'll need a donor ... not for use

4th unit : i'm running out of space, may be will be traded ... not for use

Honestly ... Do I need some treatment ??


-"Honestly ... Do I need some treatment ?? "

Yes definitely!

And your not the only one. Example. Some of the endless discussion about purely subjective perceptions about keyboards, favourite models, etc.etc.

As a corporation, HP should do the right thing and step up to the plate, and get some help for the majority of the members of this forum. I am talking about a "12 Step Program" for the HP calculator obssesed.

Sorry I woun't be able to participate. Someone has to stay home and take care of my collection.

Programming challenge - can someone write a "12 step Program" for the calculator obssesed in RPN? :>)

Edited: 30 June 2010, 11:23 a.m.


I can understand re-celling packs, but to really preserve these calculators, you'd have to re-cell every 5 years or so... the cells eventually leak, etc. I think modification is an acceptable alternative that will hopefully allow the calculators to last much longer. I re-celled a bunch of non-HP's 10 years ago, and I haven't had the motivation to begin to recheck all of them. I'm sure that they will all need them replaced again.....



I moved to using AAA and AA primary lithium cells to solve this issue.

For the classics, I made up a bunch of replacement battery packs using a 3xAAA plastic battery holder and glused metal contacts to the bottom of the holder. This fits nicely in the battery compartment.

For the spices, woodstocks and stings the solution was to just use AA lithium cells in place of the nicads.

For the topcats I used a 4xAAA plastic battery holder glued on top of one-half of the standard topcat battery pack plastic frame, with metal contacts like the classics.

So all the LED (HP and non-HP) calculators in my collection now have replaceable lithium cells that will hopefully never leak and not self discharge for many years.

But.... I remember your problem with your 19C not liking the slightly higher voltage of the AA lithium cells. I haven't had that problem yet, but it's something to be aware of.



So far, so good. I've been asking about the lithium cells for years, now, on the Forum, and I've not heard a single report of cell leaking. (O.K., a few of the 3v flashlight cells have reportedly exploded, but that's a different formulation.) Pretty good track record over about 10 years. They all still seem to work, too! Not bad. I guess we'll find out for sure once they start dying... I'll probably end up with exploding Woodstocks or something. Anyway, so far so good.


For the classics, I made up a bunch of replacement battery packs using a 3xAAA plastic battery holder and glused metal contacts to the bottom of the holder. This fits nicely in the battery compartment...


Ok - Now I know what I'll be doing this weekend. Thanks for posting this!

Edited: 30 June 2010, 7:05 p.m.


I've been very pleased with having AA lithiums in all my HP's. I can pick up any calculator in my display case and turn it on and show it or use it, even ones that have sat for years. To me, it's well worth the higher cost of the cells. They predict a 10 year shelf life, but I'm suspecting it will be much longer than that. I'll find out fairly soon: some of my cells are approaching that age.

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