HP-16C current consumption

[Sadsilence]

Last days I played around with my HP-16C after batteries had been empty. Voyager series is known for it's extremely low current consumption at time of invention. But how low is extremely low?

Instead of a new set of nonrechargeable batteries I obtained 3x Varta V40H NIMH rechargeable batteries of matching size. Really nice cells which even had a capacity of 43 mAh being above data sheet.

With a usable capacity of about 40mAh (my HP-16C starts flashing battery indicator at 3,533V) HP-16C runs following minute counter program for about 68hours:

Code:


001 - 43,22,A    LBL A
002 - 42,45,0    FLOAT 0
003 -   43 35    CLX
004 - 43,22,0    LBL 0
005 -    45 2    RCL 2
006 -   44 32    STO I
007 -      33    Rv
008 - 43,22,1    LBL 1
009 -   43 23    DSZ
010 -    22 1    GTO 1
011 -       1    1
012 -      40    +
013 -   43 34    PSE
014 -    22 0    GTO 0
015 -   43 21    RTN

266 STO 2
GSB A

Results:
Battery capacity [mAh]       40
Start time                   10.07.2017 11:33:00
Stop time                    13.07.2017 07:57:20
Run time                     68:24:20
HP-16C minute counter        4106 = 68:36:00
Precision counter [%]        0,284
Batterie indicator limit [V] 3,533
Av. current consumption [uA] 585

About 600 uA is a really impressive value for a 35 years old calculator. Other asthonishing result is, that HP 16C is only able to execute 266 DSZ loop counts per minute. 266 is calibration constant that worked best for my calculator to reach one minute cycle.