Survey posted 2001-02-08 02:43 by Andy Selle.

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It might be possible to run your calc from only a single NiMH battery, possibly in the micro form factor (you _could_ put AAA into a modified AA slot!). The recipe is simple: insert a normal 1.2V (nominal, 1.4V max, 1.0V low, ~0.9V min) battery to the appropriate slot with a little detour between the bty's + and the calc's +, insert a little (&light) circuit in the adjacent slot, that should contain a low voltage detector/suspenser (eg. diode...) and a low voltage step-up DC-DC regulator (eg. a Microchip TC125 (0.9V-10.0V, typ. 0.02mA supply[*], max. 80mA output), TC126, TC115 (typ. 0.08mA supply[*], max. 140mA out.)) or a home-made voltage multiplier using SMD's, (and some decoupling of course).
Summing the former said, it would cost one a few bucks to buy, plus some time to solder the parts together, in exchange for getting 1/4th the battery weight, plus the ability to buy only *2* rechargables in order to have a full "set" (mind you, that 2 battery slots get freed up, where it'd be possible to put the (isolated) backup one, still saving 1/2 of the weight!!!).
Problems: (1) I don't have information about the peak active current of the TI (though according to my calculations, a TC115 would do), the DC-DC could be underpowered for the power-hungry calc (-- could someone make a comparison chart of the measured max load/typical load power consumption of some TI's?) (2) ~80-90% efficiency (not a real problem) (3) lack of interest (belie me if I'm wrong).
Just a crazy idea of mine, it probably wouldn't work anyway.

*: note that even the self discharge rate of ~30%/month of a typical NiMH is greater than that, it's ~>0.2mA

Yeah, I made the first comment. Seriously why would one carry around spare batteries? If something important like a test is coming up and the calc displays the battery warning thing, then replace them. Otherwise you won't die if your calc runs out of power

I use rechargeable NiMH batteries, so if they were beginning to go dead, I would just pop them in the charger.

But before then, when I had math classes in college and all, I would just carry around a TI-36X calculator as a backup, in case of emergency (lock-up, dead batteries, or "no graphing calculators allowed on this test!").

Thats a damn good idea. I should get an extra calculator just incase my teacher say on to my grapher.

Ah>> dude you need to learn how to talk right!!

ya man, u b a bad spelin guy

I also use NiMH and NiCad in my calc> I have had the same four NiCad batteries for over two years! Cool, Huh!

I carry a 12-pack of Duracell Ultra batteries for my calculators.

Ditto. I learned better then to trust the battery indicator after getting TiChess. It takes up a lot more power then under normal operation, and I've had it kill the batteries in a couple minutes even though the indicator was still in the non-critical low battery state.

I use Energizer E2 (E Squared) batteries. I have been using the same E2 batteries since the end of last Oct. and they are still running fine. I get the battery warning indicator now only when I play ASM games for a long time, then the indicator goes away. I think E2 batteries work really well.

I use E2 batteries too but I think that they could be a little cheaper...couldn't they?

Yeah! Up here in NE Pennsylvania they are like $10 for 4 batteries. I too am using the same batteries 'since October, so they are worth it.

I USE E2 BATTERIES TOO AND YES DEY COULD BE ALITTLE CHEAPER. ESPESIALLY SINCE I HAVE A 92+ AND HAVE TO BUY AA BATT. INSTEAD OF AAA BATT.

I generally use E2 batteries in my 89, but must use my 89 much more than you, as they usually last about 1.5-2 months in my HW2 89. And it seems the most power-intensive operation performed by the calculator is the "factor(" command. A couple of weeks ago, I burned through a brand-new set of E2s in 72 hours by having it factor huge numbers. I've found that the z80-based calcs are much more battery-friendly (I have an 85, 86, and AWOL 83 besides my 89).

Those batteries are so sexy! I mean look at them!

I buy a 12 pack of Duracell Ultras too! It's to last for over 6 months and is a lot cheaper than buying three 4 packs!

Anyway I don't carry spare batteries because I like to play on my TI-86 until the very last contrast 9! And if it starts going off to annoy me then I change them as soon as I get home! :-)

How can 3 sets of batteries last you six months. Mine last me only about 2 weeks and I use Duracell Ultras too.

I had a set Radio Shack Enercell's (which are the best alkaline batteries available) last two years in my TI-86. And that included leaving the calc on overnight at least once while developing Zelda 86.

You probably leave your calculator running assembly programs all the time even when it is off such as a real time clock. There is a program in the ticalc.org archives called CTime.

Hmm...

Why do you link to that!?

( www.lauj.f2s.com )

Yes, I usually do, though not always, since it is hard to maintain power supplies for five calculators with heavy use. One can never know when a battery is going to crap out when it is most needed. Never rule out the possibility for a defective product!

I use rechargable NI-MH batteries in my calculator too. I was actually supprised they worked without giving a low battery warning, because 4.8 volts is considerably less than the normal 6.

Seems like I gotta recharge these things once a week though...

I use Nickel Cadiums in my 83, and I never get a battery low warning. When the screen fades out at contrast 9 then it's time for the recharger, which is about every two weeks.

hehe, my 89 tells me when the batteries need replacing.. hahahahahaha

So does my Casio Algebra FX 2.0 :)

why da he11 do u have Casio 4?

because it's a 286 (without protected mode) @ about 5 mhz, and has ROM-DOS built in :P

But, TI-89s run at 10 mhz. They have 890 kb of storage, including Flash-Memory. And they have the ability to program.

We're currently working on reverse engineering it (we do have ASM support now, but each add-in takes 128k using Casio's system, a new shell will be needed). Some simple DOS programs run on it unmodified (also means most DOS PC development tools can be used for it).

Also how much does a ti-89 cost? the FX2 is only 99$. Hate to get into this subject much on a TI site, but I gotta stand up for my position :)

That is wonderful!
Do you have any site where you report your findings?

Some information is already available on the Casio Elite site (http://ccp.s5.com, enough to get started programming for it), and more will be available when we find out more about accessing hardware devices directly (right now we rely mostly on DOS and the video BIOS calls supported).

If the site doesn't work, try it again a couple times.

WHO IN THERE RIGHT MIND WOULD OWN A CASIO AND HAVE AN ACCOUNT ON DA TI WEB SITE?

My TI-83 does too, but all you have to do is check the contrast number. If it's 8 or more, then replace your batteries!
I think most of us on this site has a TI-Graph Link, so if your batteries are dead for a while, who cares? You have lots of memory backups on your computer!