HP 19BII running on SR-44s

[Chasfield]

I decided to find out the likely run time for the SR-44s, given that they only have about one fifth the capacity of N sized alkaline batteries.

I made a test rig out of two strips of aluminium foil, separated by double sided adhesive tape. This I inserted into the SR-44 stack so that I could apply multi-meter-probes in series with the cells in order to measure current draw.

With the calculator in the off state, the current draw was 13.5 micro-amps. In the on state, while pressing keys, the current swung around 1 milli-amp.

With 175 milli-amp hours available from the SR-44s, it would be reasonable to expect 150 hours of actual use, or around 500 days of standby time in the off state. This battery life doesn't seem too bad and is rather better than I had anticipated.