Rechargable Batteries

[NextPerception]

anyone done anything with rechargeable batteries for there calculator.
I know it says don't use them in the ti manuel but oh well.
I havn't really looked at the topic much but I know it can be done. anyway I just was thinking about using smaller batteries so that I can use the left over space in the battery compartment for additional mods.

[Flash]

i wouldnt mind sticking something in the extra space the would freak people out when they turned on the calculator or opened the batterie compartment... id be scared as hell if i opened turned on some1s calculator and it started vibrating or making a weird noise

[NETWizz]

Oh, I did not know it says that.

Anyway, I have been using the RayOVac Rechargable Alkalines in my calculator because they are 1.5 volts and last for years!

[Arcane Wizard]

I use my wireless optical mouse's rechargable batteries when my normal batteries are low/empty, didn't know the manual said not to.

Oh, well, they work fine.

[Darth Android]

knowing TI, they will stupidly take a hint from MS and market their own batteries, then say that other batteries are very bad for the calc!

[Flash]

ti... evil... i cant beleive this... if i find out that windows and ti and planning a conpiracy against my calculator batteries im switching to casio... then giving up on calculators all together because casio sucks

[Darth Android]

well, considering that there are calcs from casio and hp that have a color screen and speakers, all for cheaper than the 83+ (or is it the 89?), casio or hp might not be a bad idea.

[62 52 53 53]

I'm still waiting for them to make calcs that normal batteries won't fit into.

[Darth Android]

really.... but they're not that stupid. i hope...

[NextPerception]

[Adm.Wiggin]

i use AAA energiser rechargeables, and there is no DUMB PROBLEMS! ARRG TI! lol... well, i didnt know the manual says not to, and i thought i had read it thouroly *cough cough* lol

[NETWizz]

I never read anywhere that you cannot use Rechargables, but I guess that could be for one of two reasons.

1. Rechargables are 1.2 volts each; thus, 4 * 1.2 is 4.8 (Alkalines are 4 * 1.5 = 6)

I serriously doubth 1.2 volts will make a huge difference; however, Garbage Collecting might not be a good idea. If I were you, I would avoid archiving, unarchiving, deleteing archived programs... unless your batteries are good.

I say this becasue if somethings happens to the flash memory on your calculator, you are in much trouble because pulling a battery does not clear flash!

Reason 2:

Internal resistance of the batteries.

The internal resistance of NiCd or NiMh rechargables is much lower than that of alkaline batteries, so under load, the actual voltage drop accross a calculator would not decrease much.

Here is how it works:
As the resistance of a device decreases, its load incrases i.e. it draws more current expressed in milli ampres. Well, as the resistance of a device drops, the resistance of the battery stays the same. Let us say the battery has 1 ohm of internal resistance and the device you are running has 99 ohms of resistance. The device you are running gets 99% of the voltage of the battery, and only 1% of the batteries power is wasted accross the battery.

Now, let us say that the device you are runnign does something intensive i.e. Garbage Collect, the ohms of resistance drops let us say to 1 ohm. Now, if the battery has 1 ohm of resistance, and the calculator has one ohm of resistance, only 50% of the power makes it to the calculator and the rest heats up the batteries.

Ever held a paper clip across a battery and felt the battery get hot? Have you also noticed the paper clip will remain cold?

Now, take a piece of toster wire (high resistance wire) over 90% of the batteries power will go to the toaster wire turning it red hot!

Why internal resistance is imporatant.

Although an alkaline has 1.5 volts under low load, as the load increases the voltage drop across the alkaline will increase more than that of a NiMh (1.2 volts) where eventually the NiMa will be supplying more voltage than an alkaline under hight loads.

All in all, I don't see the big deal using rechargables. I use rechargable alkaline becasue they have the same internal resistance as regular alkaline, and are rated at 1.5 volts. Plus, they recharge 25 times making them last about 4 years in a calculator.

In everything else, I use NiMh because they are obviouly superior under load.

[Arcane Wizard]

[Adm.Wiggin]

mine are 1.2 and they have worked for almost a year they work great! they are NiMh Jbirk, thank you for explaining the battery thing... that really helps

[NextPerception]

what about lithium ion rechargables
they can have over 1600 recharges
anyone have some general info about the voltage and resistance for them.
I would look it up but I just wanted to know if anyone uses them before i did.

[NETWizz]

The voltage is generally over 4 volts per cell!

They generally produce 2000 mah current vs 1500 for alkaline, 1800 NiMh and 1200 for NiCD. Their internal resistance is extremely low, so they are great in high drain devuces.

Theay are small for what they do.
on 4v cell at 2000 mah could do 8 units of work.
Where 4 alkaline at 1500 can do only 6 units of work.

For their size, they pack the biggest punch. They are used in the tiny cellphones you see, my ham radio, et cetera.

Fact:

On LI-Ion cell could run a portable CD player for over 100 hours, and it would be no bigger than one aaa.

The cons:

They really charge only 300 to 500 times.
Vary heavily with temperature. In otherwords the voltage is different at different temperatures, and the internal resistance varies too.
Cannot be force charged. i.e. you cannot force high voltage and ampres through them to recharge them quickly. Instead, you must charge them slowly under strict conditions, so you need a microprocessor controlled charger.

They self discharge at an alarming rate meaning after you charge them, they go dead even if you don't use them.

They are very expensive.

Okay, one last thing:
As you know, wattage is calculated by multiplying the voltage by the ampres, and there are (1000 milli units = 1 unit)

Alkaline 1.5v @ 1500 mah (1.5 * 1.5 = 2.25 watts maximum output)
If you go over this, and teh battery is cool, it will probably provide more for a short burst, but the heat inside will very quickly heat up, the internal resistance will increase, and it will die or at least need rest for a while before seving again.

Li-Ion

4v @ 2000 mah (4 * 2 = 8 watts maximum output)
If you do something that requires more than 4 watts, your in big trouble.

resistance = Voltage/Current

So, if you know the voltage is 4 and the maximum current is 2 ampres, you can calculate the minimum resistance to 2 ohms.

That means if you put a load of less than 2 ohms, it will short the battery, and with the power of a LI-ION heating itself if you go over the current draw, it will melt the packaging and everything! Even if it doesn't, the chemicals are so sensitive to heat, it will never charge again.

Now compare that to a NiCd

Although the maximum allowed is 1200 mah, if you go over it, the battery will drop its voltage and heat up, but after cooling and being recharged will probably produce 100% of what it did before.

Lastlyplease note that heat is the biggest threat.

If a battery is rated at say 1 amp, and you draw 20 amps for .01 seconds, the battery will probably meet the demand with adequate supply because the anode is already positive and the cathode already has a negative charg, and it will probably not heat up either. Think of a camera flash. There is no way an Alkaline battery could do a continuous camera flash, but it can peak the battery above the max for a very brief period of time and not harm the battery.

[Flash]

and i was just about to go out and buy some batteries... at least now i know what kind to buy, thanks jbirk

[omni]

They also said not to mix brands or old batteris with new ones. Will anything bad happen if I do do that?

[Flash]

HA! my compartment is a batterie graveyard...
batteries include:
1 - energizer - not sure if it works anymore
1 - procell - not sure how old it is
1 - duracell - also not sure about
1 - rayovak - new last of its kind from the package i found

in concluesion i wouldnt be surprised if the rayovak is the only one that works propery... im thinking about going to the store tomarrow to buy a few more

[omni]

Does you calculator work properly? (Flash)