Adapting cell battery to HP 41
02-25-2019, 07:40 PM
Post: #6
 Dieter Senior Member Posts: 2,397 Joined: Dec 2013
RE: Adapting cell battery to HP 41
(02-25-2019 03:31 PM)Artur - Brasil Wrote:  The circuits themselves use only 85nA;
The HP in standby mode I think something around 1mA.

So the power consumption of the voltage converter (which I assume is what you call "the circuits") is negligible compared to the calculator in standby. In sleep mode it seems to be 10...30 µA which still is two magnitudes more than the 85 nA you stated. So this seems to be no problem.

(02-25-2019 03:31 PM)Artur - Brasil Wrote:  So, I believe 850mAh/1.085mA --> 780 h --> 30 days in standby mode!

In am not an Electrical Engineer, so please excuse me if this is a stupid question, but... the battery has 850 mAh times 3,6 V = about 3000 mWh. Since there is a voltage converter with 6 V output the calculator consumes 6 V times 1 mA = 6 mW when in standby. So the expected battery life should be more like 3000 : 6 = 500 h or about 20 days.

Which is about the same as what four NiMH N-cells deliver, and about half the capacity of N-Alkalines. But then again it's 3x what you can expect from a rebuilt 82120 pack with 1/3 AAA cells. So this cell phone battery seems to be a good choice.

Dieter
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