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Dave Britten · 04-25-2020, 02:06 AM

(04-25-2020 12:11 AM)Don Shepherd Wrote: Dave, I can't speak for the LR44 cells in the early 12c's because my oldest 12c is from 2001 and it has the single 2032. I have two of the newer fast 12c+'s with 2 2032's as well. These 2032 cells last a long time. I can't remember when or if the original cells needed replacement.

The LR44 cells in my 17b and 17bii's do need replacement more frequently than the 2032's. I buy them in bulk on Amazon at reasonable prices. I have recently acquired a 19b and 19bii that use the N cells, I'm anxious to see how long they last because they are a pain in the arse to change (side batt door, but in good shape).

Yeah, the Pioneers, while pretty easy on the batteries, are definitely more demanding than the ultra-low-power Voyagers. Regarding N batteries, I've tried to find some info about typical battery life for a 41CX, but haven't found anything. I suspect it varies wildly depending on modules used.

(04-25-2020 12:53 AM)BobVA Wrote: Well, the energy capacity is about the same for LR44 and the 2032 (150 x 4.5 = 675 mWH vs. 220 x 3= 660 mWH) so, theoretically, they should have a similar lifetime about if the power requirements of the two models are similar.

Okay, then the two models probably have about the same battery life.

(04-25-2020 12:53 AM)BobVA Wrote: I wasn't sure of that assumption, so I did some quick measurements on my 12c Platinum (single 2032 but unknown variant) and a regular 12c and got the following results

Code:

On Off 12c 67.1 uA (0.3 mW) <0.1 uA (<0.45 uW) 12P 29.6 uA (0.1 mW) 1.5 uA (4.5 uW)

I didn't measure current for processing keystrokes, running programs, etc. figuring the average calculator spent the majority of its time in the off state, and the idle state after that.

So, based on all that, I'd expect the batteries in the 12c to last longer due to it's much lower "off" power consumption.

And here's some the reasons that could be wrong, or right for the wrong reasons:
- measurement of current that low with a simple DVM is fraught with peril (but I think the relative measurements are perhaps more reliable).
- I couldn't get a reading on the 12c standby current as it dropped below 0 on my meter after a few seconds. I was guessing it was closer to 0.1 uA than, say, 0.01 uA, but I don't know.
- I don't know exactly where the Low Battery warning is tripped on either model, nor the energy under discharge curve for either battery type when reaching that point. Both silver oxide and lithium batteries are relatively flat, so the latter *may* be a wash.
- There are a large number of variants of the single 2032 12 Platinum and I don't know if I have the one you're asking about.

But, the most important thing about this experiment is I discovered a set of leaky batteries in my 12c! :-)

I also discovered a little piece of paper in the 12c battery compartment on which the previous owner had noted the battery change dates. They seem to bear out the Voyager reputation for battery life:

- December 22, 1993
- June 1, 2005

I added today's date to the paper and put it back in the battery compartment to keep his or her experiment going.

Interesting that the Platinum has much higher standby current draw, but much lower on/idle. My 1xCR2032 model is a standard 12C, not a Platinum; I wonder which of your two samples it more closely resembles.