MAX8881 and DS2490 Characterization for Cells
Rechargeable AA cells are very popular for a large variety of
portable applications. The number of brands is also high, and the cell
quality can differ considerably. Cell capacity is sometimes different
from that specified, and the capacity often deteriorates dramatically
after a limited number of discharge cycles. ....
See Maxim Application Note - Simple Characterization Circuit for Rechargeable AA Cells
https://www.maximintegrated.com/en/design/technical-documents/app-notes/3/3874.html
This characterization circuit, plus a PC and some software, accurately
measures the full discharge cycle for a rechargeable AA cell. Cell
capacity and output resistance can easily be determined from the curve
resulting from these measurements.
In Figure 1, the simple circuit is connected to the USB port of a PC. No
external power source is required because power is extracted from the
USB bus voltage. U1 (DS9490R) is a USB dongle that converts the USB
protocol to the 1-Wire® protocol, thereby allowing the PC to communicate
with the key circuit component (U2).