Operation; A) Three Stage Charge Regimen - NewMar Phase Three PT-70a Installation & Operation Manual

IV)

OPERATION

A) Three Stage Charge Regimen

The Phase Three Battery Charger utilizes the three stage charge regimen which is widely
recommended by battery manufacturers for allowing the fastest possible recharge time
without loss of batteries' electrolyte (gel or liquid) which may be caused by sustained charg-
ing at higher voltages.
This three stage regimen is initiated each time a.c. is first applied, when drained batteries
are most likely to be encountered, and proceeds slowly or quickly through each stage de-
pending on the battery's relative state of charge. (This also occurs when the reinitialize but-
ton on the optional remote panel is activated; see Remote Panel Option section for more
information). Note: An audible "clicking" noise from an internal relay may be heard when the
charger switches from one phase to another. This is normal operation. The charge regimen
proceeds as follows:
1) Bulk Phase: When batteries are significantly discharged the charger responds initially by
delivering a high amount of d.c. current, at or near the charger's maximum rated output, in
order to rapidly replenish them. It is during this stage that charging current is maintained at
a high level as battery voltage increases. Bulk charging continues until battery voltage
reaches the "charge" voltage level (where batteries are at about 75-80% of capacity). A cur-
rent limit circuit prevents charger overload during this maximum output stage. Note: During
this bulk phase the charger is in a "constant power" mode; therefore, as output current
increases, output voltage decreases, and vice versa. Full output voltage is achieved and
maintained only when the charger switches to the absorption stage. (See Specifications
section for output maximums at 115V and 230V input.)
2) Absorption Phase: During this second stage of the charge cycle, battery voltage is main-
tained at the "charge" voltage level. Output current begins to taper off as the battery plates
become saturated. Charge voltage is maintained until the current sensing circuit detects that
output current has tapered to about 5-15 % of charger rating*. At this point the batteries are
at about 95 % of full charge and the Phase Three charger switches to the third and final
stage of the charge cycle.
* Note: The absorption phase may also be ended by the time-out circuit. See section B fol-
lowing for a complete explanation of the purpose and functioning of the time-out circuit.
3) Float Phase: For extended battery life the Phase Three then automatically switches to a
lower float voltage level. This float charge keeps batteries at peak condition without over-
charging. The charger may be left in this stage for lengthy periods of time without attention
(though periodic checks of electrolyte level in flooded batteries is recommended). It is not
necessary or recommended to shut the charger off when this stage is reached.
A typical three stage charging cycle is illustrated in FIGURE 4.
10
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