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Installation and Operation
charge for a minimum of 24 hours. After discharge, the float charge should be applied as soon as possible.
It must not be delayed more than 7 days in any case.
The charger should be sized so that the full charge rate is at least 17 Adc per battery string.
The float charger should be set to maintain the batteries at 13.62 Vdc per battery in a string (2.27 volts per cell) at
77°F (25°C). Other temperatures require voltage compensation within a range of 2.21 to 2.29 volts per cell. See
Temperature Compensation on page 15.
Freshening Charge
A maintenance or "freshening" charge is given to batteries that have been in storage. The freshening charge
must be appropriate to the battery model. All charging should be temperature-compensated (see page 15).
The charge should proceed as described above using a float charger. The voltage should be 13.62 Vdc per
battery in a string (2.27 volts per cell).
Charging (EnergyCell RE)
EnergyCell RE batteries are usually charged using a "three-stage" charging cycle: bulk stage, absorption stage,
and float stage. Most OutBack chargers follow this algorithm. However, not all chargers are designed or
programmed the same way. The settings should be checked and changed to match the recommendations
below if necessary. Contact OutBack Technical Support before using other charger types.
Bulk Stage
The bulk stage is a constant-current stage. The
charger's current is maintained at a constant
high level. The battery voltage will rise as long as
the current continues to flow. Each battery
model has a recommended maximum current
limit (see Table 6 on page 19) which should not
be exceeded. At excessive current rates, the
battery's efficiency of conversion becomes less
and it may not become completely charged.
The battery may permanently lose capacity over
the long term.
The purpose of the bulk stage is to raise the
battery to a high voltage (usually referred to as
either bulk voltage or absorption voltage). The
acceptable voltage range is 14.4 to 14.8 Vdc per
battery in a string (2.40 to 2.47 volts per cell). If
batteries are in series, this number is multiplied
by the number of batteries in the string. This
stage typically restores the battery to 85% to
90% SoC, if the charge rate does not exceed the
maximum shown on page 19.
Absorption Stage
The absorption stage is a constant-voltage stage. It is established upon reaching the desired voltage in the bulk
stage. This causes the charger to begin limiting the current flow to only what is necessary to maintain this
voltage. A large amount of current is required to raise the voltage to the absorption level, but less current is
required to maintain it there. This requirement will tend to decrease as long as the absorption level is
maintained, resulting in a tapering current flow. The amount of absorption current will vary with conditions, but
will typically decrease to a very low number. This "tops off the tank", leaving the battery at 100% SoC.
The battery is considered to be completely full when the following conditions are met: The charge current must
taper down to a level of current equal to between 1% and 2% of the total battery amp-hours (while
14
DC Volts
Bulk
Hours (typical)
Amperes (typical)
Bulk
Hours (typical)
Figure 12
Three-Stage Charging
Absorption
Float
Absorption
Float
900-0127-01-00 Rev C
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