The analysis that I received is shown on the next page. During the discharge portion the battery voltage follows the
classic NiCd/NiMH form: an initial fast drop in voltage, a gradual decrease as the battery loses its charge, and a fast
drop at the end when the battery is fully discharged. After discharge, the charger is turned on and the battery voltage
rises quickly as it recovers, then rises gradually as the battery accepts the charge, and then peaks when it’s fully
charged. The voltage drops after the peak as the charge current is reduced from the 600mA peak charge current to
the 60mA equalization charge current.
Figure 17: Sample battery analysis result of a discharge followed by a charge cycle.
Now look at the text below the graph. In the One Hour Discharge: section you can see that the battery with a rated
capacity of 600mAh, was discharged 580mAh. This battery tested at 97% of rated capacity (580mAh / 600mAh x
100%). A battery with a capacity of over 90% of its rated value is considered in good condition. One with between
80% and 90% of its rated capacity is acceptable, however one below 70% to 80% should be replaced (these figures
depend on the battery and it's intended application). For the discharge capacity to be used as an acceptance criteria,
the battery must be fully charged before the test. The NiCd and NiMH BARs that come with UBA Console run for two
cycles, the first cycle leaves the battery fully charged so that the next cycle can give an accurate result. For SLA and
lithium batteries either start the test with a fully charged battery, edit the BAR so that the discharge follows a charge or
run the BAR twice.
Page 12
The UBA Let's Get Started Guide
“Battery discharged” is the tested
capacity of the battery.
