Xantrex Technology Link 2000 Marine Instruments User Manual


 
19
HOW TO TELL WHEN A BATTERY IS
FULLY CHARGED
(CHARGED BATTERY PARAMETERS)
MULTIPLE STAGE CHARGING SYSTEMS
If you are using the charger in the FREEDOM, the battery is charged when the system
switches to the Float cycle. If another manufacturer's charging system is being used it
should be adjusted so the transition from Acceptance Charging to Float will occur when
the charging current, at the Acceptance Voltage (14.4/28.8 V typically), drops to below 2%
of the battery capacity. (See the description of the Ideal Charge Curve on the previous page.)
CONSTANT VOLTAGE CHARGING SYSTEMS
Constant voltage charging systems have restored as much charge to a battery as they
can when the voltage reaches the maximum regulation point (a typical 12 V system is set
at 13.8 V) and the charging current drops to less than 1% of the battery capacity. (It can
take more than eight hours for a battery to reach this state of charge.) If you are using an
engine-driven charging system and trying to limit engine run time, you probably will charge
only until the current drops to 5% or 10% of capacity. The LINK 2000 should be
synchronized to whichever of these charge levels is reached in normal operation.
USING SPECIFIC GRAVITY
Accurate battery current measurement is necessary to determine the charged
parameters in the two previous methods. Specific gravity of the battery can also be used
to determine the charge level of a battery. Regardless of the charging system used, a battery
is charged when the specific gravity shows no increase for three hours, when measured at
half hour intervals. Typical specific gravity @ 77 °F for a fully charged liquid electrolyte
battery is 1.265 + 0.050.
CHARGE EFFICIENCY FACTOR (CEF)
AND HOW IT IS USED
The CEF determines the rate at which the Link 2000 counts back up during charging
to compensate for the inefficiencies of the charging process. The CEF has a factory
default value of 87%. That means the charger must return 1.15 Ah to the system for the
battery to restore 1.0 Ah.
The CEF is automatically recalculated (and averaged over the last few cycles) after
every charge cycle if the battery has been discharged more than 10% of the declared
battery capacity and the charged parameters for voltage and current (selected automati-
cally or manually in the setup procedure) are met for five minutes (may vary by setup).
Additionally, 100% of the kWh removed must be returned during charging.
Continual CEF compensation ensures that the battery state of charge and the Link
2000 stay in sync. Monitoring the CEF over time helps assess changes in performance of
the battery or charging system.