Battery Draw (HP-35)

[SlideRule]

An excerpt fromIEEE Spectrum, April 1974, page 30

FORUM
…
Too much!
  The caption for Fig. 5, page 29, of the December 1973 issue of Spectrum states that the HP 35 calculator draws 500 mA from its internal battery. This would be very poor design for a 3-cell NiCad pack rated at 450 mAH . The actual battery drain depends upon the display; ranging from a low of 60 mA to a high of nearly 100 mA. This will, indeed, permit about four hours of battery life if left turned on continuously. Actually, with only short periods of use the unit can provide several days of satisfactory operation. When recharge is required, the furnished charger will completely renew the battery in 10 to 15 hours, even while the calculator is in use on line. Recharge current averages about 45 mA, whether the calculator switch is ON or OFF!
…
            Lloyd W. Root, Sun City, Ariz.

  The caption for Fig. 5, page 29 should have stated that the HP-35 draws 500 mW, not 500 mA. Actual peak currents are in the neighborhood of 150 mA with all digits on …—Ed
…