Re: Hp-67 Power life Message #9 Posted by M. Joury on 15 Sept 2011, 5:03 p.m., in response to message #8 by Fouad M. Kaadou
You have to measure the voltage under load otherwise the reading is probably off.
Also, note that a NiCd or NiMH battery has a VERY flat discharge curve. That means that it will display high voltage until just before it dies. An example of such is the old HP-41 battery pack. With regular Alkaline batteries the calculator could run for hours, days, even weeks, with a low battery indication on. But with a NiCd pack you were lucky if you got 30 minutes, or even less, after the low batt lit up.
The point here is that the voltage difference will be very small between a fully charged battery and one the is at 50% charge. This is particularly true of the battery is tested with no load on it.
Cheers,
-Marwan
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