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HP Forum Archive 17

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48SX battery run
Message #1 Posted by John Mosand on 16 Sept 2007, 11:58 a.m.

Today, I replaced the batteries for the second time. I bought my 48SX when it was introduced. Has anybody experienced a better battery life for the 48SX ? On the other hand, I also have a 10C which my friend who gave it to me claimed that he had never replaced the batteries. It is still running - in my shirt pocket :-) I should add that my 48SX has been in daily use, with two expansion cards (EQ Library and Math Pack).

      
Re: 48SX battery run
Message #2 Posted by megarat on 16 Sept 2007, 8:24 p.m.,
in response to message #1 by John Mosand

I concur, I always felt that the HP 48sx had tremendous battery life. Specifically, I bought mine used in late 2002 and used it a few times a week and never had to change the batteries until I sold it just a few months ago, when I put in new batteries as a courtesy. As far as I know, those batteries still had another several years on them. (That's with a 128k RAM card and the library card installed.)

Compare that to the HP 48gx I had for less than a year; I had to change the batteries after maybe six months, and it didn't even get much use during that time. I think it ate those batteries while it slept.

-cam

      
Re: 48SX battery run
Message #3 Posted by JoeFrisco on 17 Sept 2007, 7:18 p.m.,
in response to message #1 by John Mosand

I bought mine in 1993. I think I am on, maybe, the third set of batteries. I changed out the first set when I took the PE exam in 1995. My HP48SX does not get a lot of use lately. The current set of batteries, has been in the calculator since 1991-1992. I check them occasionaly for corrosion. It does have two cards in it. But I do not think they draw any power. They are the equation library and the PE EE Exam card by Chotkeh.

            
Re: 48SX battery run
Message #4 Posted by John Mosand on 18 Sept 2007, 2:13 p.m.,
in response to message #3 by JoeFrisco

JoeFrisco, you probably mean that the batteries have been in there "since 2001-2002"?? And, DaveJ, thank you for those details, measuring projected battery life span, etc. while installed. (I have a good meter, but I don't know how to do that...)

                  
Re: 48SX battery run
Message #5 Posted by DaveJ on 18 Sept 2007, 5:36 p.m.,
in response to message #4 by John Mosand

Quote:
JoeFrisco, you probably mean that the batteries have been in there "since 2001-2002"?? And, DaveJ, thank you for those details, measuring projected battery life span, etc. while installed. (I have a good meter, but I don't know how to do that...)

You've gotta have 3 hands to hold one battery half out, hold the probes in contact, and push the buttons at the same time. Also, the angle you hold your tongue at is crucial!

Dave.

                        
Re: 48SX battery run
Message #6 Posted by JoeFrisco on 20 Sept 2007, 9:55 a.m.,
in response to message #5 by DaveJ

You are correct 2001-2002

                        
Re: 48SX battery run
Message #7 Posted by designnut on 20 Sept 2007, 2:14 p.m.,
in response to message #5 by DaveJ

A handy tool to access batterry currents is a thin strip of PC material with copper on both sides and solder such leads as you may need to either side copper. Then it may be inserted in any battery path to obtain a current reading. Sam Levy

      
Re: 48SX battery run
Message #8 Posted by DaveJ on 18 Sept 2007, 7:01 a.m.,
in response to message #1 by John Mosand

I just measured the current drain on my 48SX at 12uA when off with fresh batteries and no cards. That would equate to an absolute best case life of around 100,000 hours (11 years) for Alkalines in the off state. That is of course more than the shelf life of the batteries.

I got 3.2mA when ON, doing nothing but displaying the stack. That would be roughly 375 hours best case continuous operation.

Dave.

            
Re: 48SX battery run
Message #9 Posted by Paul Dale on 18 Sept 2007, 4:34 p.m.,
in response to message #8 by DaveJ

And in coma mode? (On space from memory)

- Pauli

                  
Re: 48SX battery run
Message #10 Posted by DaveJ on 18 Sept 2007, 5:33 p.m.,
in response to message #9 by Paul Dale

Quote:
And in coma mode? (On space from memory)

I think it was 2uA, but I can't recheck because it looks like I've just killed something! Just some innocent current probing and now the screen has all of the right half pixels on and the hourglass, no response from keys. Oops.... Anyone know how to fix?, I've tried shorting the battery contacts etc but there is simply no response at all, can't even turn the calc off.

Interesting, when a key is pressed and held down the current jumped to a steady 6mA.

Dave.

                        
Re: 48SX battery run
Message #11 Posted by DaveJ on 18 Sept 2007, 6:08 p.m.,
in response to message #10 by DaveJ

It's ok now, seems to have fixed itself after a while!

Yes, 2uA after pressing ON-SPC.

Considering that normal off mode gives you a measly 12uA, what's the point?

If you want to save power on your 48SX I'd recommend pressing the keys quicker!

Dave.


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