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Power Consumption Measurements for an HP-41CV
Message #1 Posted by Dan Grelinger on 26 May 1999, 11:15 p.m.

I made some measurements on an HP-41CV, (non half-nut), and will share them. The mesurements were made when powering the CV with a Ni-Cd battery pac with recently replaced Ni-Cd's.

Running a looping program with constant BEEPs - 5.20 mA Running a looping program, no BEEPs - 5.20 mA Running catalog 3 - 5.10 mA Machine on, but idle - 543 uA (0.543 mA) Machine off - erratic, but eventualy settling around .750 uA (.00075 mA)

HP claimed that the Ni-Cd battery pack (HP82120A) capacity was 65mAH, and that alkaline N-cells had a capacity of 500 mAH.

I found it interesting that running the sounder used no more power than a silent running program. I was also surprised to see such a low idle and off current. The off current was wildly erratic (from .1 uA to 20 uA) when the machine was first turned off. It took about 30 minutes to finally settle at the above number. There appeared to be some interaction with the meter, i.e. as it automatically changed scales, the current measured would vary, probably due to changiing input resistance of the meter.

I will do an HP-41CX, as well as an HP-41CX with a HYPER-41 speed-up, and post the results.

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