Testing parallel strings of storage batteries

An apparatus for testing a first storage battery in a bank of storage batteries, the bank formed of at least two storage batteries electrically coupled together, the apparatus comprising:

• a first Kelvin connection configured to couple to the bank of storage batteries, the first Kelvin connection including a first and second electrical connection;
• a second Kelvin connection configured to couple to the bank of storage batteries, the second Kelvin connection including a first and a second electrical connection, the first and second Kelvin connections configured to couple across at least the first battery;
• a time varying forcing function source configured to apply a forcing function between the first electrical connection of the first Kelvin connection and the first electrical connection of the second Kelvin connection;
• a voltage sensor configured to sense a voltage between the second electrical connection of the first Kelvin connection and the second electrical connection of the second Kelvin connection and provide a sensed voltage output which is at least partially a function of the forcing function;
• a current sensor configured to sense an electrical current which flows through an electrical connection in the bank of storage batteries, the sensed current related to the first battery, and responsively provide a sensed current output which is at least partially a function of the forcing function;
• and
• a microprocessor configured to determine a condition of the first battery as a function of the sensed voltage and the sensed current.