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Battery capacity



As mentioned in my previous post entitled "Lights," the energy available
from flashlight cells varies depending upon load, duty cycle, temperature
and manufacturer.  Manufacturers are often reluctant to divulge figures.
The following milliampere-hour capacities were published in a British
catalog in 1989.  Duracell's chemical formulation has been changed since
then, and capacity has allegedly improved.

Several sources rate alkaline D-cell capacity at 9-10 ampere-hours.
Test parameters for the mA-hr data in the table below are not known.  The
_relative_ capacities which I have calculated (column 6) should be valid
within any chemical system and manufacturer.


ALKALINE-CELL CAPACITIES

                       Capacity     mA-hr
Duracell            --------------  rel. to   See
part no. Size Volts  mA-hr   W-hr   D-cell    note
--------+----+-----+-------+-------+---------+-------
MN1300    D    1.5   15000   22.5    1.00
MN1400    C    1.5    7000   10.5    0.47
MN1203         4.5    4400   19.8    0.30      1
MN1500    AA   1.5    2250    3.4    0.15
MN2400    AAA  1.5     800    1.2    0.05
MN9100    N    1.5     650    1.0    0.04
MN1604         9.0     500    4.5    0.03      2
          F    1.5   20000   30.0    1.33      3

Notes:

1.   MN1203 is the 3-cell battery used in Petzl(tm) headlamps from France.
     The cells are larger than AA, smaller than C. They are not commonly
     available in U.S.  An adapter for the Petzl lamp holds three AA-cells
     which, as shown above, have only about half as much capacity.

2.   MN1604 is a 9-volt "transistor" battery with snap connectors.  Unlike
     similar batteries which are stacks of flat rectanglular cells, MN1604
     contains six cylindrical cells smaller than AAA size, connected by
     spot-welded stainless-steel straps.  The individually-insulated cells
     can be separated for special applications.

3.   F-cells are used in 6-volt lantern batteries, however, many alkaline
     lantern batteries now on the market actually contain D cells.  Most
     lantern batteries now depend upon internal springs to maintain
     contact, rather than the traditional spot-welded jumpers between
     cells.  The result is unreliability:  If the cardboard end-plates
     become wet and soggy, the springs relax and contacts fail.  Water
     between the contacts causes corrosion and further bad connections.

--

Frank     reid@indiana.edu