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HP Forum Archive 13

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Excitement about my new HP34C
Message #1 Posted by Larry Corrado, USA (WI) on 4 June 2003, 11:35 a.m.

My sister keeps her eyes open for HPs and TIs for me at rummage sales. She recently found and bought, at a typical rummage sale price, an HP-34C in near-perfect condition, with manuals, adapter, and case. I powered the unit up when I got it home, and it seems to work perfectly. The keys feel good, and the display is bright and clear. The most serious problem is a couple of tiny corrosion spots on one of the battery clips. Now I'll have a chance to see firsthand if what Luis, Norm, and db (and others) have been saying about the 34C is true.

The box that came with the unit also contained a near-mint TI-30. There was also a second spice adapter and case, but no sign of the machine they might have come with originally. Maybe if my sister had arrived 10 minutes earlier...

Larry :-)

Enjoy it!
Message #2 Posted by Vieira, Luiz C. (Brazil) on 4 June 2003, 4:18 p.m.,
in response to message #1 by Larry Corrado, USA (WI)

Hey, Larry!

Thanks for mentioning my name this way. I keep whatever I posted about the HP34C and I have actualy an image of it when I was at the university, at the Library. The owner bought an HP41CV later, and kept it's old fella. What called my attention was the fancy [f], [g] and [h] prefix keys and the white + gray keyset intead of white + black in all other spices.

The HP34C is a must! I like much because of memory amount, continuous memory, RPN ( of course) and both SOLVE and numerical integrate.

Enjoy it!

Luiz C. Vieira - Brazil

Hey Larry,
Message #3 Posted by Norm on 4 June 2003, 9:41 p.m.,
in response to message #1 by Larry Corrado, USA (WI)

Hey Larry,

How much you want for it ??

I was just kidding. HP-34C is old klunker. Not worth very much. You gonna hate it. Can't see RED LED's in the bright sunlight. Batteries will be dead in 20 minutes. You'll hate it so I can take it off your hands.

Did you read my post in the 'memories' forum.

Look for this title: "HP-34C Better than S*X".

If you understand how to take the case apart (dont try if you dont know how!) then lube the slide switches with a few drops of "Tri Flow" (the teflon version of WD-40).

After 3 months, my unit seems to have accepted that very well as a slide-switch lubricant. They feel silky and smooth.

You dont want to run the slide switches w/o a lubricant, you'll wear out the various surfaces.

I just bought a pair of Photo Lithium AA batteries for $6.00 . I think thats the best way to keep an HP-34C fed. Of course, you could go the rechargeable route also.

Have fun !

Norm, please...
Message #4 Posted by R Lion on 5 June 2003, 11:51 a.m.,
in response to message #3 by Norm

just curiosity: how do those batteries last in your 34c?


Batteries (Hi R Lion)
Message #5 Posted by Norm on 5 June 2003, 1:22 p.m.,
in response to message #3 by Norm

Hi R. Lion,

Well, ideas that sound good, dont necessarily turn into good results. Let me provide battery information, in response to your query.

The idea that I described, is a disposable battery that lasts much longer than Alkaline, and then just reload the batteries when they fail, and to heck with the charger. The cost of such reloading is just the luxury tax on enjoying RED LED's on demand.

OK, well, the idea isn't panning out so far. YESTERDAY I bought Photo Lithium AA batteries. They were "Energizer". Today, as I reached for the package, it felt disturbingly light. It felt like I'd been sold a bunch of air.

I looked for lifespan estimates on the MBA/Marketeer prepared slick chrome-colored packaging, and found none.

I called the 1-800 number, and a stammering and hesitant technical rep finally said this: that Alkaline AA batteries provide 2850 mA*Hr and the Lithium AA that I hold in my hand provide 2900 mA*Hr. What I sense here (but cannot prove yet) is another 'Carly Conspiracy'. They are packaging air into the cells.

FACT, not conjecture: Energizer does this with their "lantern batteries". You know the ones, the big square/rectangular batteries from 'Brady Bunch' era when everybody took their kids camping and roasted marshmallows and sang songs (now they just stay home and listen to rap music and watch 120 channels of Cable TV for $50 a month) Those lantern batteries are supposed to be made of FOUR E CELLS. "E" cells are bigger than "D" cells.

But Energizer just packs them with "D" cells like for your flashlight, and fills the rest of the casing with cardboard. If you compare the weight, by hand, between a Duracell lantern battery, and an Energizer lantern battery, the difference is immediately apparent. Duracell builds them to original specification and doesn't sell you cardboard instead of a battery.

Back to the conjecture, I speculate that they carefully trimmed the Lithium cell to deliver 2900 mA*Hr so that their marketing MBA advertising can state "delivers more power than Alkaline" (yeah, 2% more). Then they charge $6.00 for these batteries, instead of the 0.70 they would get for a pair of Alkaline.

So, I smell a rat. The only way to fight the Carly types, is to not patronize their junk. So I still have the receipt and I didnt open them, so these go back to the big-box merchant.

THIS IS NOW IN THE DOMAIN OF LEARNING..... can anybody fairly state what the energy density is of Lithium vs. Alkaline, and whether a Lithium cell should fairly deliver more mA*Hr than Alkaline for equal volume ??

I always thought that Lithium did have more energy density. If not, I need to learn this. As to the ripoff on the lantern battery, that is not conjecture, that's established fact.

Re: Batteries and toilet paper :-)
Message #6 Posted by R Lion on 5 June 2003, 1:40 p.m.,
in response to message #5 by Norm

At least here in Spain you can get that info only in rechargable batteries, but not with normal batteries: I have ever wonder why they are not required by law to put the total charge in the package. I can't understand why the customer must to buy "eyes shut".

The same applies to toilet paper: why don't they say the total length??!!


Edited: 5 June 2003, 1:42 p.m.

Re: Batteries (Hi R Lion)
Message #7 Posted by Ron Ross on 5 June 2003, 1:44 p.m.,
in response to message #5 by Norm

Li ion batteries do indeed have a higher energy density. But there are two issues to consider. Lithium is much lighter than other metals, so the energy per weight is much greater (not the same as density). But they also DO HAVE a higher energy density, just not the dramatic improvement you were led to believe. Factor in the weight AND volume and you get your great stats (and THAT IS EXACTLY HOW MARKETING DOES THE CALCULATIONS).

But there is one last kicker with Li ion. It is TOXIC and hazardous, hence much better (thicker) packaging. All that adds to cost, without giving you much in way of size advantages for a AA or AAA package (actualy Li ion also have a different natural charge rate and voltage than a typical 1.2-1.5 Volt cell (something like 3.8V). All this adds up to problems to marry older electronics to newer battery technology.

lithium AA replacements
Message #8 Posted by Ellis Easley on 5 June 2003, 1:55 p.m.,
in response to message #7 by Ron Ross

I don't know if these are lithium ion cells - they are not rechargeable and the voltage is 1.5V. When I first heard of them I wondered if they might contain a small 3V cell and a DC-DC convertor to generate 1.5V! Or just diodes to waste the extra voltage. But David Smith is familiar with them and he says they are a different lithium chemistry that produces 1.5V.

lithium vs alkaline
Message #9 Posted by Ellis Easley on 5 June 2003, 1:47 p.m.,
in response to message #5 by Norm

I don't know about the energy density but I thought the main attribute of lithium batteries as drop-in replacements for other types of common batteries was the shelf life. I remember ads saying to use them for important things like smoke and carbon monoxide detectors, and I found a lithium 9V rectangular battery in a smoke detector when I moved into my house. But Dr. Mike, who likes to use lithium batteries in his calculators, seemed to indicate that he liked them because of the long operating life. I found what may have been his first post on the subject, and he talks about the long shelf life being one reason for using them, but also states:

These batteries have about 5 times the life of alkaline batteries
I don't know if he means capacity or shelf life. Here is a link to the thread:

9 volt Lithium has 5x life?
Message #10 Posted by Norm on 5 June 2003, 3:24 p.m.,
in response to message #9 by Ellis Easley


Saying that a 9 volt Lithium has a 5x longer life sounds very, very familiar to me. If this were a democracy, I would vote agreement, until somebody gets me a databook.

Remember that such a battery has got 6 little cells inside of it, at 1.5 volts each.

It may be that the marketeers didn't get much of a profit win by changing to 6 microscopic little cells in (and leaving the rest air) they may be 6 full-size Lithium cells inside that 9 volter,so its got more capacity.

Since the "AA" comprises of only a single-cell, they may have said 'ka-ching' and dollar signs lit up in their retinas, and they cut down the cell-size so that it was the same power output as an AA Alkaline.

the display consumes everything in a SPICe
Message #11 Posted by Norm on 5 June 2003, 3:28 p.m.,
in response to message #10 by Norm

Hi, you were wondering what uses the most power in the unit, like was it the display.

It IS the display. The display consumes a ton of power. The way to see this, is watch the behavior of the "low battery" indicator when its marginally coming on.

It goes out when the display has few segments lit, glows brightly when the display is well-lit.

Sometimes when I have my HP-34C on, and I'm sort of "in-between" calculating things, but I dont wish to shut it off, I just absent mindedly hit a "1" so that the display is relatively off.

When your running a program all day, the display is substantially off.

When it just sits displaying a number to 4 decimal places, that's actually when your using a fair amount of juice.

IMAGINE the fine displays that could be made nowadays using large chunks of diced silicon wafer, and, the technology of high-efficiency LED's. Can't be doing things like that, after all, 'innovation' is a naughty word.

Re: the display consumes everything in a SPICe
Message #12 Posted by Dave Shaffer on 6 June 2003, 12:12 a.m.,
in response to message #11 by Norm


"I just absent mindedly hit a "1""

To save even more juice, just hit a decimal point - I used to do that with my '35 for the same reason. (Saves wear and tear on the on/off switch - I think I should try some of that lubricant you mentioned the other day - can you get less than a pint of it at a time?!)

that Tri-Flow lubricant
Message #13 Posted by Norm on 6 June 2003, 4:15 a.m.,
in response to message #12 by Dave Shaffer

Hi Dave, that sounds good, to hit the "." instead of a "1" to extend battery life.

However, with the spice HP-34C, I get a "0." so its still best to hit the "1".

About TRI-FLOW.... its generally superior to WD-40 because it contains teflon powder that clings to the metal after the oils have evaporated. In the case of the electric switch of a 34C, the teflon lubricates it, BUT, the particles dont apparently interfere with making electrical contact. At the molecular level, I find that easy enough to accept.

WD-40... know what that stands for ?? It is a military product and a military spec, last I heard. It stands for "Water Displacement 40". Basically, after the soldier has waded across the rice paddy, he is supposed to shoot WD-40 into the rifle mechanism to clear the water out. That oil has absolutely nothing special about it, its cheap and runny and a lousy lubricant, except it is semi-compatible with water and displaces the water.

So is WD-40 a good lubricant really? No, try some SAE 30 motor oil, or some grease, or some Tri-Flow, if you want to keep something well-lubricated.

Because Carly has cousins who are in charge of Home Depot, you can't go to a place like Home Depot and buy Tri-Flow. They only sell cans of WD-40, because its cheap and makes a lot of profit, and because it doesn't solve your problems, which is very important to them from a strategic standpoint (they want you to drive back & forth to their store over and over, not solve your problems. If they solved your problems then you wouldn't come back... with a home, that is.)

TRY A BICYCLE SHOP. Try a smaller hardware store, like a "True Value" (maybe). Those in the know like Tri-Flow. Its a lasting lubricant, thanks to the teflon powder, for serious mechanisms, like guns, doorlocks, carkeys. I'd use it in a pinch over WD-40 for a cardoor hinge, although, foaming aerosol spray-grease is the best there. (you can get it from your local underground network of "amsoil" fanatics).

I'm just saying that a minute quantity was just super for the spice 34C slide switches, they are very silky smooth now. I applied with a Q-tip, rubbed it into the circuit board, and the metal contacts. Allowed a little onto the plastic surfaces also. It's very very silky smooth, and because of the teflon particles should stay that way for awhile.

Of course, there may be other good lubricants for that also.

Re: that Tri-Flow lubricant
Message #14 Posted by Trent Moseley on 6 June 2003, 2:23 p.m.,
in response to message #13 by Norm


Can "Tri Flow" be applied externally with a Q-Tip? I have a 25C and a 67.


Nope !!
Message #15 Posted by NH on 6 June 2003, 8:21 p.m.,
in response to message #14 by Trent Moseley

Nope, you cannot lube the slide switches w/o opening them up.

This is an aerosol can like WD-40 .

Now, if you have a doorlock, or a rifle mechanism, you can stick the wand in there and blast it and you dont really care what happens to the excess. It fizzes and it foams and some of it spills out and some of it runs in.

You can't treat your calculator like that.

You would take it apart, get a drop of the lubricant onto a Q-tip, and carefully apply it to the metal contacts. And also, to the plastic surfaces that guide the switch.

I am friendly to the notion of other lubricants. I dont know that this choice is the best, only that it works. And that you must keep the slide switches lubricated with SOMETHING or you will wear them out.

Re: Nope !!
Message #16 Posted by Trent Moseley on 6 June 2003, 11:25 p.m.,
in response to message #15 by NH


I don't use the old 25C that much so I'm just going to be very gentle when I use the old ON-OFF switch. It's working OK so there is no way I'm going to open that baby up for a lub job.


Re: that Tri-Flow lubricant
Message #17 Posted by Ellis Easley on 6 June 2003, 11:22 p.m.,
in response to message #13 by Norm

Of course, there may be other good lubricants for that also.

David Smith recommends Radio Shack "Lube Gel" - well, he says it is "surprisingly good" - he mentions it sometimes when switches are being discussed, but he might mean on toast. I kind of thought he said it was teflon based, but the tube doesn't say so. I have a tube, haven't used it yet, but this thread had motivated me to open up my 34C and lube the switches with it. Only one thing bothers me - at the bottom of the text on the back of the tube, it says "Product may vary from depiction"(*). Since there are no pictures, just a lot of words saying it is the best lubricant ever made, I guess this disclaimer means it might be no damn good. I worked for Tandy once, and I know some of Carly's cousins work for Radio Shack!

(*) maybe it only works below -45F and above +450F, reacts with salt and fresh water, attracts dust, won't stay in place - it slides, drips off and breaks down, especially under normal temperature and humidity conditions. It might be corrosive and toxic and it might not work on anything.

BTW, they actually refer to it as an "adhesive lubricant".

I'm going to try it anyway!

Re: 9 volt Lithium has 5x life?
Message #18 Posted by Ellis Easley on 5 June 2003, 6:16 p.m.,
in response to message #10 by Norm

But Dr. Mike was talking about AA cells. Maybe it's like you said about the lantern batteries, maybe some brand lithium AA's have more capacity - well, his post says he's using Eveready.

(completely unrelated) - You know, just change two letters and "eveready" becomes "overeasy".

And on the 9V batteries - they could have three 3V cells in them, couldn't they?

I've got a feeling the 3V chemistry is the one that has long shelf life AND high energy density (seems like it should have a step up just for having 3 volts!)

bad news for lithium battery lovers???
Message #19 Posted by glynn on 6 June 2003, 9:01 a.m.,
in response to message #18 by Ellis Easley

Hi! Sorry I got into this forum thread late.

Dr. Mike was *(note the use of past tense as a possibility)* perfectly accurate when he stated that his Eveready/Energizer Lithium AA batteries lasted 5 times longer. Norm, you used some and they worked, didn't you? And the weight of the NEW ones tipped you off that there was some difference?

I worked at a battery store for a bit over two years. The Eveready Lithium AA's were a great innovation, and we sold quite a number of them. The chemistry, NOT "Lithium-Ion" but Lithium dioxide, had been around for some time and is at the heart of cr2032 coin cells and 123a photo batteries. It is light and powerful, and-- up until the Eveready innovation-- was a 3v cell (it is the potential difference in the electrodes that determines the cell voltage difference, the chemicals in between are the storage medium).

Eveready did a great thing by creating special electrodes so that they coud make it in a standard form factor, the 1.5v AA. By doing this, they had a battery that would run a digital camera with display about 3-4 times longer. In some devices, like calculators etc., the difference was 5x, and Eveready was not afraid to trumpet this loudly. They had a lock on the patents, and so would be the only source for these 1.5 Lithiums.

We were looking forward to AAA and C and even D 1.5's. As Eveready became "Energizer Corp", what was promised seemed to be always a few months away.

I've left the battery world, but it does NOT surprise me to hear that SOMETHING has changed in the AA. Law-enforcement was warning us to alert them when selling bulk quantities of them, as they found certain home drug-labs were opening them to get at the lithium inside, using it as a catalyst in a reaction for making household "speed". Consumers were reluctant to buy the lithiums because of the price-point of them compared to akalines. And retailers were insufficiently equipped to inform consumers that the particular chemistry involved was classed as "household waste", just as alkalines are, and not a particular hazard unless concentrated considerably (lithium occurs naturally in similar concentrations).

So, has Energizer corp changed the AA Lithium? From the answer given Norm over the phone, it would appear so.

Energizer has slick but confusing packaging. They sell many lines, with "platinum" versions etc... and I would ask Norm to carefully check his packaging for the claims made. But if they have STOPPED saying that it lasts "up to 5 times longer than Alkalines", BE VERY AFRAID.

This may well be a case of Innovate, then Switch.

2900 mA*Hr
Message #20 Posted by Norm on 6 June 2003, 1:34 p.m.,
in response to message #19 by glynn

The only hard numbers I've got is the 2900 mA * Hr on the "Lithium Energizer AA".

A standard AA Alkaline is 2850 mA * Hr.

I can't prove that I smell an MBA, errrr, a rat,

but it sure looks that way. I am going to look around for a Lithium AA cell that really would have triple capacity (or more) which means it should be above 10,000 mA * Hr .

Let U know if I ever find any.

- Norm

Re: 9 volt Lithium has 5x life?
Message #21 Posted by Michael Meyer on 7 June 2003, 2:14 a.m.,
in response to message #10 by Norm


If you read in this old, and other old threads, these are Lithium Maganese cells, and they do put out 1.5V. Some of the more technically savvy members have described these in detail.

They are lighter, and also have at least a 10 year shelf life.

I can't vouch for the marketers, but if you doubt the "5x's" more energy, try seeing how many photos you get out of your digital camera with the best alkalines you can find vs. the lithium cells. I swear: I don't sell these things. I do buy them: 4 packs are $8.99 at Office Depot, and with coupons, even less. I bought a bunch when they had a buy one, get one free sale.

I can take over 300 flash photos on my trusty old Olympus 3030 camera. Again, I only get a quarter as much out of alkalines.

And even in "high drain" calculators such as my 19C, I'm still on my original sets in all of them. (I'll admit, I don't use most of my calcs more than a few minutes at a time. That's why I like these cells.... I can pick up any calculator from my collection and have it work without having to worry about charge status. I should be able to pick one up in 5 or 10 years and STILL have it work.)

Hey, I don't care what others do. And I still have a stack of freshly NiCd celled packs I can put back in the calcs. But for me, I just really like these lithium AA's.


Re: 9 volt Lithium has 5x life?
Message #22 Posted by Ellis Easley on 7 June 2003, 2:52 a.m.,
in response to message #21 by Michael Meyer

I wonder if what we are dealing with here is the same problem with alkaline batteries in the 41C when using the card reader. The battery life is effectively shortened because after some of the charge is used up, the voltage drops under a load that used to receive full voltage. My little digital camera has this problem, I think. When it says alkaline AA's are too low, I can still use them for a long time in a radio - plenty of Amp-hours left but the resistance has gone up. This exact same problem would apply to a 67 (for instance) because of the card reader motor. I don't know how the 34C compares to a radio in terms of current consumption.

Re: Batteries (NiCd)
Message #23 Posted by Paul Brogger on 5 June 2003, 2:53 p.m.,
in response to message #5 by Norm

I just bought a pair of NiCd soldertab AA's at Radio Shack and rebuilt my 34c's battery pack. I charged 'em up, and have been running a program loop all day (as in over 7 hours so far). Still chugging away. I'll report the final duration if & when the thing ever quits. (No, it's not plugged in!)

So, it seems to me that NiCd batteries will work just fine. Why bother with anything else? (Worried about the recharger damaging the calculator?)

(Say, which should run the thing down faster: entering "all eights" and letting it sit, or running a program?)

By the way, I took most of two of the solder tabs off (one "plus" and one "minus") by bending 'em back & forth a few times. The other two I simply intertwined at the "connected end" of the pack. I made sure the polarity was correct, added some vinyl tape, replaced the battery pack label/sticker, and it seems as good as new.

Re: Batteries (NiCd) -- nearly nine hours run time
Message #24 Posted by Paul Brogger on 6 June 2003, 9:05 a.m.,
in response to message #23 by Paul Brogger

FYI, the first charge lasted nearly nine hours running.

Today I'm going to punch in all eights & let it sit. Should make for a dramatic comparison.

Re: Batteries (NiCd) -- ~ 5.5 hours "display time"
Message #25 Posted by Paul Brogger on 6 June 2003, 3:32 p.m.,
in response to message #23 by Paul Brogger

FYI, I punched in all eights and CHS ("-8,888,888,888.") and noticed the low power indicator at about the 5:15 mark. At about 5:30 I noticed the low power indicator had gone out, but the display otherwise looked normal. At about 5:50 I noticed the display had blanked.

I suppose the other thing to test (given other comments in this thread) is entering "1." and seeing how long that lasts . . . Maybe next week.

Re: Batteries (NiCd) -- ~ 5.5 hours "display time"
Message #26 Posted by Ellis Easley on 6 June 2003, 11:29 p.m.,
in response to message #25 by Paul Brogger

Are those regular NiCads, and not NiMH?

Re: Batteries (NiCd) -- ~ 5.5 hours "display time"
Message #27 Posted by Paul Brogger on 8 June 2003, 5:41 p.m.,
in response to message #26 by Ellis Easley

NiCd -- I decided against the NiMH because the package specifically recommends a charger made for NiMH batteries. That may be a Tandy ploy to sell chargers, but I didn't want to take a chance. (I suppose that issue has already been addressed in this Forum at some other time, but I didn't take time to look it up.)

NiMH in an HP classic......
Message #28 Posted by Norm on 9 June 2003, 2:00 a.m.,
in response to message #27 by Paul Brogger

I wuz wondering about that also, can you just shove a NiMH into the HP classic (25C, 34C, etc) and extend the charge/discharge times w/o a care in the world,


does the NiMH require a special charger.

I would certainly vote for just shoving them in there and trying it. However, making them leak would not be very encouraging. I am very curious but I too did NOT take the time to look up what's already been said about that.

NiMH powering an HP82143A
Message #29 Posted by Vieira, Luiz C. (Brazil) on 9 June 2003, 2:27 a.m.,
in response to message #28 by Norm

Hi, Norm;

I'm using a rebuilt pack with NiMH cells taken from a Motorolla® battery pack. As you know, NiMH cells have a higher voltage, close to 1.5Vcc, and I noticed that the printer is running fine. What I would like to discuss here, and I thouhgt Captain Zener :) would also like it a lot, is that discharging curve for NiMH cells is different, so I think we would have a longer O.K. working time but a shorter not-O.K. end-of-curve, causing the equipment to fade-out quickly after the first low-batt signalling. I'm still waiting to see.

My first concerns are about voltage. If all HP P.S. designs are based on battery voltage as a reference, than I'll add two diodes, crossed-parallel, in series with batteries, packs of four units. This would lead a .6 to .7 drop when both discharging and charging procedures are taking place. What do you think of it as a safety precaution? I did not use the HP82143A for long printing activities mostly because of this. I just printed a few CAT listings and followed one program in TRACE mode, and it worked fine.

Have you seen my post about batteries a few weeks ago? If not, it's here:

Battery Question (and my e-space is back).

I'd like to further discuss this subject, if you and others want to. I'ts the "heart and soul" of our beloved calcualtors and I think this subject demands special attention always. Discussing power supplies is something to be done for as long as Electronic Equipments exist.


Luiz C. Vieira - Brazil

Edited: 9 June 2003, 2:32 a.m.

Re: NiMH powering an HP82143A
Message #30 Posted by Norm on 9 June 2003, 9:55 a.m.,
in response to message #29 by Vieira, Luiz C. (Brazil)

Hi Luiz,

I guess the thing I dont understand, is that I thought the manufacturers of NiMH had meant it to be a batter that would upgrade equipment designs using NiCd .

That is, the cell voltage was about the same, charging methods are similar, its just the storage capacity was higher ?

I would be trying a direct swap, i.e. a simple upgrade to NiMH without modifying anything.

But I've never tried it, nor did I check mfr. data sheets.

NiMH powering an HP82143A (brief)
Message #31 Posted by Vieira, Luiz C. (Brazil) on 9 June 2003, 10:02 a.m.,
in response to message #30 by Norm

Hi, Norm;

the NiMH four-cells pack measures 5.8 Vcc when resting a few hours after fully charged. When charging, it reaches about 6.5 Vcc and falls to 6.2 when fully charged with 15mAH charging current.

For the records.

Luiz C. Vieira - Brazil

Re: NiMH powering an HP82143A (brief)
Message #32 Posted by Chan Tran on 12 June 2003, 3:26 p.m.,
in response to message #31 by Vieira, Luiz C. (Brazil)

Luiz, I power my HP82143A printer with 4 AA NiMH cells. It works fine and longer per charge compares to the original sub C cells. I charge them overnight using the original charger. Eveready said that the one think to watch for is not to overcharge NiMH. Otherwise everything should be fine.

Thank you for your feedback!
Message #33 Posted by Vieira, Luiz C. (Brazil) on 12 June 2003, 4:26 p.m.,
in response to message #32 by Chan Tran

Hi, Chan Tran;

my 82143A is still being powered by a NiMH pack. I did not put it to charge yet because there is no low BATT signaling so far. I removed the pack yesterday and measured 5.3Vcc after about 1 hour operation (spare use). This pack had their cells fully charged separately in a "smart" charger.

I'll keep everybody updated when I have more news. After David's warning about NiMH being too close to NiCad as for their operating voltage, I'm reviewing a lot of concepts, notes and mostly I'm finding a way to recalibrate my instruments and to fine-tune my load resistors.

Best regards ant thank you again, Chan Tran.

Luiz C. Vieira - Brazil

Re: Thank you for your feedback!
Message #34 Posted by David Smith on 12 June 2003, 5:52 p.m.,
in response to message #33 by Vieira, Luiz C. (Brazil)

I would just use high capacity NiCad cells in the 82143A (and especially the HP97). HP's original packs were 1100-1300 maH. AA NiMH cells and modern sub-C NiCad cells are around 1800maH. These units put a pretty good slug of current into the batteries... they charge the cells in about 5 hours. That is why the machines gets so warm. It is also why the HP97 battery packs don't last so long. I think the AA NiMH cells may heat up too much if you left the charging continuously and their life would be shortened. An 8 hour charge should be just fine though.

Sub-C NiMH cells (3200+ maH) should be just fine though. They are rather hard to find and VERY expensive.

Re: NiMH in an HP classic......
Message #35 Posted by David Smith on 9 June 2003, 10:52 a.m.,
in response to message #28 by Norm

As long as the charge circuit is a slow trickle charge (like the HP calculators), you can drop NiMH cells into it without modification. I verified this with an apps engineer from one of the major battery manufacturers. If your cells have three times the old capacity, you need to charger them for three times as long. But since NiMH cells do not have nearly the "memory effect" of NiCad cells, you can partially charge/discharge them without affecting their life. 1800maH AA cells are standard these days. 2100-2200maH are available.

I have noticed that different machines sense the battery-low condition a bit differently. My HP67 turns on battery low about 30 minutes before cutting off. Some spice machines indicate battery low for a few minutes after full charge with m odern batteries (NiMH or NiCad).

Re: Batteries (NiCd)
Message #36 Posted by David Smith on 7 June 2003, 2:48 p.m.,
in response to message #23 by Paul Brogger

My 1800 maH NiMH cells run spice machines for over 15 hours. I have not tried the 2100 maH cells that are just now appearing in public.

One interesting thing about newer batteries in Spice machines. The low battery light can flicker on for up to half an hour of use after a full charge. Seems modern cells put out a slightly higher full charge voltage than the old ones. The reduced duty cycle of the DC-DC converter pulses seems to fool the low-battery circuit.

Re: NiCd vs. NiMH -- What about Leakage and Corrosion?
Message #37 Posted by Paul Brogger on 9 June 2003, 2:03 p.m.,
in response to message #23 by Paul Brogger

As I consider replacing NiCDs with NiMH in an infrequently-used collectible, their relative costs, total power capacities, and even the memory effect are of little import. (I don't suppose that everyone will agree with this . . . )

More important is the direction this thread has taken: whether voltage differences can adversely affect the calculator's electronics.

Another aspect is chemical leakage and resultant corrosion. Certainly, NiCDs are capable of causing damage. Does anyone know whether NiMH are more or less likely to spill their guts inside a battery compartment?

Also, are there other trade-offs associated with the various battery options which should be considered?

Re: NiCd vs. NiMH -- What about Leakage and Corrosion?
Message #38 Posted by David Smith on 9 June 2003, 3:58 p.m.,
in response to message #37 by Paul Brogger

The voltage of the NiMH cells is almost identical to NiCad. Fully charged they output around 1.33V bs 1.42V for NiCads. They both ouckly drop to 1.2V nominal. At 1.0V per cell they are considered fully discharged. The shape of the voltage vs time curves are fairly similar.

Most modern batteries are sealed fairly well, but given time any seal will leak. Most of the battery leakage problems encountered in old machines were caused by the calculator being tossed in a drawer for a dozen years with the battery left in it... you wouldn't do that now... would you?

I think that most of the HP41 alkaline cell leakage problems on the far left terminal were caused mainly by one major manufacturer's cell designs. I think there were only two people who made the "N" cells at the time. Again if you remove the batteries when they are dead or for long term storage you should nt have any problems.

NiCd vs. NiMH -- 2 different stories
Message #39 Posted by Norm on 9 June 2003, 9:18 p.m.,
in response to message #38 by David Smith

Well, between Luiz and the other guy, there's 2 different stories.

Luiz says the NiMH voltages are higher, the other guy says that the voltage curves are the same.

I had heard the curves are pretty much the same.

But never compared either one.

Re: NiCd vs. NiMH -- 2 different stories
Message #40 Posted by David Smith on 11 June 2003, 1:38 p.m.,
in response to message #39 by Norm

Rest assured that the NiMH cells are a slightly (0.1V) lower voltage than NiCads thoughout most of their discharge curve. I've designed numerous rechargeable instruments over the last 25+ years and am intimately familiar with their characteristics.

Time to re-evaluate and listen
Message #41 Posted by Vieira, Luiz C. (Brazil) on 11 June 2003, 6:50 p.m.,
in response to message #40 by David Smith

Hi, David;

again, it's time to re-evaluate whatever I've been doing and measuring on batteries. 25+ years is something I cannot face.

Thanks. I'll redraw and reassemble my battery-related measuring devices (a few components and metters). I'm surely getting into mistaken procedures.

Luiz C. Vieira - Brazil

0.1 V Lower ??? no way, gotta be higher
Message #42 Posted by Norm on 11 June 2003, 9:00 p.m.,
in response to message #40 by David Smith

Your post said NiMH is 0.1V lower than NiCd.

Tell me you meant the other way around. I dont want exact graphs and a science lesson, but just a gut feel. I mean, is the Piper cub faster than the Lear Jet, or is it the other way around. I just need to know which outperforms, not the actual speed data.

I thought for sure that NiCd had too low a cell voltage (the stinkers always wound up at 1.25 V or so, classic 'dim flashlight' appearance which is why nobody likes them and it would be IMPOSSIBLE to go 0.lV lower than NiCd or nobody will want them. I thought NiMH was higher if anything.

- Norm

Re: 0.1 V Lower ??? no way, gotta be higher
Message #43 Posted by David Smith on 12 June 2003, 5:41 p.m.,
in response to message #42 by Norm

Nope, NiMHs are just a touch lowere than nicads. A fully charged nicad starts off at 1.44V per cell, the NiMH around 1.35V.

This drops to a constant value around 1.2V for most of the discharge cycle for NiCads. The central part of the NiMH cell discharge curve is more highly sloped.

Near the end of the charge both cells drop to 1.0V where they are considered fully discharged.

Message #44 Posted by Norm on 12 June 2003, 5:46 p.m.,
in response to message #43 by David Smith


I believe you . The NiCd has more voltage than NiMH.

Hard to get excited about a battery that delivers less voltage than NiCd. Display would probably be significantly dimmer for red led's.

Wouldn't be very good with a flashlight either.

my nicad/NiMH uses
Message #45 Posted by db(martinez,california) on 12 June 2003, 8:48 p.m.,
in response to message #44 by Norm

i think that NiMH are good for peorle who can't be bothered deep cycling their batteries like they should, and/or applications where giving a full cycle is not usually practical like a digital camera. in a camera the battery cycle is usually not in line with the dump-the-card-and-start-over cycle. so they have their place but i would rather use the cheaper, higher capacity, longer lived nicad in a calcer or radio or camping light.

i did get a 4 pack of AA & AAA nimh cells for a song once at the flea and they are great. however, i still deep cycle them out of habit. i should give the AA's to my sweetie for her camera. taking the nicads out and putting them through my smart charger each time she uses it here is a drag.

Display Brightness vs Battery Type
Message #46 Posted by Michael F. Coyle on 12 June 2003, 10:57 p.m.,
in response to message #44 by Norm


The NiCd has more voltage than NiMH.

Hard to get excited about a battery that delivers less voltage than NiCd. Display would probably be significantly dimmer for red led's.

I doubt there'd be any difference at all. The LED's are driven from a constant-current circuit (as far as I can tell), so the display brightness will be constant until the battery reaches end-of-charge.

And while on the subject of different battery voltages, a 0.1V difference in a 2.5V battery pack is just 4%. I can't imagine any circuit in a calculator that would be that sensitive to the difference. (Besides, the 6V and -12V supplies are regulated.) Except maybe for the low-battery circuit.

So by all means, use NiMH batteries. I am.

- Michael

Re: bleccch
Message #47 Posted by David Smith on 13 June 2003, 4:50 p.m.,
in response to message #44 by Norm

The difference is totally unnoticeable. The machines up convert the battery to a regulated constant voltage for the electronics and display.

Re: Batteries (Hi R Lion)
Message #48 Posted by Michael Meyer on 7 June 2003, 2:29 a.m.,
in response to message #5 by Norm

Oh, NO!!

Don't tell me they've changed my favorite batteries! Those bastardos... I mean, those battery-retardos!!!

I'd go stock up on them, but I'd probably get arrested. I'd better stick with powering my calcs with anhydrous ammonia. (Just kidding!)

My only hope is this: if they've really changed the capacity of the lithium AA's, they'll clearly show it in the digital photography arena. Then it's back to the new ultra-capacity NiMH cells. (I hate how they're dead in just a few days rather than a few decades for the lithium ones...)


P.S. I did get a major "score" on alkaline AA's. A local "one hour photo" store was about to permanently close when I happened to walk in. I asked if they had any boxes of old parts: transformers, etc. They said no. "But we do have this big box of batteries we don't know what to do with..." These were the cells they pulled from disposable cameras before sending them back to be recycled. I must have been given over 500 nearly "full" AA industrial alkaline batteries. For the next few years, it'll be "use and throw!"

Message #49 Posted by Norm on 7 June 2003, 12:58 p.m.,
in response to message #48 by Michael Meyer

If you have 500 AA batteries, put them in the refrigerator.

For batteries and film, it effectively stops their aging process, if they are put in the fridge.

Re: Refrigerate IN PLASTIC, KEEP DRY
Message #50 Posted by glynn on 7 June 2003, 3:12 p.m.,
in response to message #49 by Norm

Before refrigerating, fold some paper towels to put around them in a plastic bag or tupperware. Moisture (from the air) condenses on the batteries, rusts them. That you don't want.

and also Refrigerate
Message #51 Posted by Norm on 7 June 2003, 5:57 p.m.,
in response to message #50 by glynn

and also refrigerate pills, medications, and SUNSCREENS i.e. outdoor tan lotions.

Ever got a nasty sunburn from "expired" Sunscreen? After about 3-4 years it loses all effectiveness. I had this happen once. Kept rubbing it on, but kept getting a feeling like "K19 Widowmaker". Had a million blisters by the end of the day. Thanks Johnson & Johnson.

Carly has cousins at Johnson & Johnson, where Sunscreen is made. They don't elaborate on the issue of expiration; and the date-codes typically are so tiny that you dont notice them.

If you refrigerate sunscreen then it becomes a non-issue.

OT and also Refrigerate
Message #52 Posted by Randy Sloyer on 8 June 2003, 8:35 p.m.,
in response to message #51 by Norm

Hi Norm,

With all that stuff in your refrigerator, where do you keep the beer? :^)

I keep a single bottle
Message #53 Posted by Norm on 9 June 2003, 1:58 a.m.,
in response to message #52 by Randy Sloyer

I keep a single bottle of beer in between all the boxfuls of batteries, 35mm film, suntan lotion, and bottles of aspirin.

No room for a block of cheese however. Have to do without.


Luiz and Norm -
Message #54 Posted by Larry Corrado, USA (WI) on 5 June 2003, 2:36 p.m.,
in response to message #3 by Norm

Luiz, thanks for your note and, in general, for your always-interesting and knowledgeable postings.

Norm, I appreciate your offer to take this antique off my hands, but I think I'll pass. Thanks for the reference to your "Memories" article. I like calculators, but I don't get quite that worked up about them: I still prefer s*x over solving a third-degree polynomial. However, I do think I'm going to like the 34C better than the Woodstocks I used for 25 years.

Thanks for the tip abut the switch. The switches on the 34C are very smooth; however, I have a 38E and 38C that I'll check. I've never had a Spice apart, so I'll read up on what others say about disassembly before doing anything drastic.

Regards, Larry

(O.T.) A necessary acknowledgment
Message #55 Posted by Vieira, Luiz C. (Brazil) on 5 June 2003, 5:01 p.m.,
in response to message #54 by Larry Corrado, USA (WI)

Hey, Larry;

I'm the one to thank you.

You know, I like dealing with technology and my fellow country mates will tell if I am wrong when I say Brazil is not an R&D place, and if you deal (or want to deal) with toptech you'll find many difficulties here. I deal with HP calculators since the 80's and in 2000 I found MoHPC. At that time I had my eight working HP calculators simply spending a few microAmps from their batteries to keep their (empty) memory contents. After the first contact with the MoHPC folks, I put them (the calcs) all back to work. First I was only "listening" (reading). Then I dared writing here and there, I made some mistaken statements and learned that all posts must have a password... Anyway, I found an enjoyable e_place.

You know what? At that time I had no HPIL (thank you, D.M.), I was not aware of HP41 internal modifications, I was not told about CCD, PPC, HEPAX and PANAME modules... I felt as Johnny Castaway after rescue. I got into touch with some sort of information that further extended my own. I know I learn fast, and if the subject is technology, I put my heart on it... my daughter, healthy relationship and s*x come first, of course...:)

I learnt a lot here, and I tried to deserve being amongst the giants, even if I do not consider myself this tall. And believe me, when I open the Forum's page I feel as meeting old friends for the best chat ever. And I know I'm understood, even when my English knowledge fails.

Your words make me think I'm not in the wrong direction.

That's why I'm thanking you.

Best regards.

Luiz C. Vieira - Brazil

(Dave; please, forgive me using this space for a personal relief... I felt as if I could.)

Edited: 5 June 2003, 5:27 p.m.

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