MAN-000020-00 REV A
19
Finish:
Finish mode will hold the current into the battery constant, and the battery
voltage will slowly rise. The charge cycle will terminate when one of three conditions
exists: The charger has been in the finish mode for the full duration of the finish
timer, the Finish dV/dt is reached, or the Finish Voltage is achieved. The Finish dV/dt
is reached when the battery voltage rises less than the Finish dV (typically
~5mV/cell) over the length of time defined by the Finish dt (typically ~20 minutes).
(Figure 15)
Equalize:
The equalize mode ensures that all cells of the battery are equally
charged. During charge/discharge, the inner and outer cells of the battery will tend to
be at slightly different voltage. The equalize mode charges at a low fixed current
(~5%) for a fixed amount of time (Typically ~3-6 hr), and ensures that all cells are
fully and equally charged.
Figure 15: Finish charge termination criteria
Opportunity Charging:
Opportunity charging utilizes a temperature sensor
(thermistor) on the battery to allow more rapid recharge of the battery, without the
risk of damage to the battery. The thermistor may be mounted to an intercell strap or
post (external type), or mounted through the cover of the cell to monitor the
electrolyte temperature directly (internal type). The thermistor is connected to the
charger through the auxiliary contacts of the battery connector. The charger uses the
temperature that is calculated from the thermistor to alter the voltages at which the
charger transitions to the CV and Finish/Equalize modes of operation, and to limit
the temperature rise of the battery to a safe level. See Appendix D for further details.
Installation instructions for the thermistor can be obtained at
http://powerdesigners.com/.
