Batteries with the same make, model, capacity rating and age (date code within 6 months) will generally conform to the model below:

  1. New batteries will test within 10% of each other (+/- 5%) in forming a healthy string.
  2. Batteries testing within 20% of each other (+/- 10%) still tend to perform equally well during a timed discharge test.
  3. A battery that tests 30+% below the average conductance of the highest 10 cells in a string will have difficulty making 80% of its rated capacity.

Reference Value Quick Tips

  1. The best baseline is one established for that specific battery installed at that site for 90 - 180 days.
  2. Generic values should only be used as a broad guide when no other data is available.
  3. If no value is available variation among batteries in a string can also be an indicator of degradation.