Power usage of calculators

[brickviking]

(07-05-2014 02:24 AM)JimP Wrote:  This presents an interesting question -- of all the calculators available on the market today (including HP and "the rest" eg TI, Sharp, Casio, Canon, etc.) -- maybe a question answerable by an expert collector -- when compared head to head for battery longevity, which brand comes out the best?

I suppose there are potentials for lots of categories -- graphing, business, scientific, dual power (ie solar/battery) so it's not an uncomplicated question. There is also the type of battery -- alkaline vs. flat Li type. Maybe a silly one, though...

I thought I'd bust this out into its own thread and start things off, as I've got both an older Casio (fx9750G+) and a slightly newer model of the same calculator (fx-9750GII). I also have a HP-50G. I chose these three because they all use four AAA batteries.

Comparing the raw "this is how much power we say we use" on the backs of each calculator, my fx-9750G+ says 0.06 W, the fx-9750GII says 0.35 W, and Eric Rechlin's thread back in 2007 describes some HP calculators in detail. From that, I can ascertain the HP-50G uses between 0.09 W and 0.56 W (idle to flash writing).

I created a grocery program on the fx9750G+ to accept input and display output. I enter in prices for items in five categories, and sum the categories as I go along. The calculator's normally running full-time waiting for input while it displays the current totals, with input taking about 0.3% of the time. It's a very specific limited use-case that most people won't have and I accept that, however it's the only thing I've had to do my testing.

As for long-term usage, I've found since 2008 that I can use my fx-9750g+ on a fortnightly basis (for about a couple of screen-on hours each time) for over a year before I need to replace a set of alkalines. I haven't had either of the others that long, neither do I use them in the supermarket, though I'd be interested to see how the GII compares for battery usage. As for the HP, I haven't written up the program I use on the Casio, that's going into another thread.

I got a Casio fx-82MS a few years before the 9750G+ which appears to use 0.0002 W, and I haven't changed the single AA battery yet. This now gets pretty minimal use though to be fair, as I normally pick up either the GII or the HP-50G now I have them. I also got a Canon F-804P back in 2008 which only uses 0.06 mW on two LR44 cells, but this gets even less use than the fx-82MS, and it spends practically all its time powered off. Still, it would appear it uses the least electricity of all the physical calculators I own.

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