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The final stage is the Float Charge: This mode is the charge mode that the battery is under most of the time for a
properly designed system. Once the batteries are brought to a full state of charge, the float charge mode maintains the
batteries at a voltage level of around 13.2 to 13.7 volts (for a flooded, 12 volt lead acid battery. By applying the
required amount of charge current to offset any load the battery might be powering, as well as overcoming the
batteries natural self-discharge, the batteries longevity is greatly increased.
Another charge mode incorporated by many chargers (and the HVAD) is the equalize charge. This mode is not a part
of the normal charge cycle, but is instead initiated (either manually or automatically based on a timer) to help mix the
electrolytes of the battery. During normal use, the battery’s chemical mix becomes stratified. (Separated from top to
bottom). An equalize charge uses approximately 10 percent higher voltage to help mix these elements in the battery.
Equalize charging also helps bring all of the batteries in a multi-battery bank to an equal state. Most people agree that
an equalize charge should be run once every 10 to 40 days, for 2 to 16 hours. During this charge cycle quite a lot of
gassing will occur, which causes the fluids to be mixed and the plates to be "cleaned". An equalize charge is not
recommended for sealed batteries.
The HVAD also incorporates a “ReBulk” set point. Should the battery voltage drop to the “ReBulk” set point for
more than a few seconds, the controller will exit the current charge mode and start a new bulk mode. If the Bulk
mode is already active, then the controller will restart the countdown timer to force a new full-length bulk mode
charge.
The HVAD incorporates the 3 stage algorithm discussed here with the some limitations that are due to the fact that the
controller uses a mechanical switch. The primary limitation is the number of times per minute the solenoid can be
switched on and off without damage or premature failure to the solenoid. This limits the controller in systems that
have small battery banks and high current charge sources. When such a condition exists, the controller will not be
able to react as quickly as a solid-state controller and may allow the voltage to rise or fall further than optimal. To
alleviate this condition, it is recommended that your charge source(s) not exceed the battery bank’s amp-hour capacity
by more than four times. That is, this controller is best suited to a system where the combined solar/wind energy is
not capable of fully charging the battery bank faster than 4 hours. Higher current sources will tend to whip the
voltages up and down, with a loss of efficiency. A PWM or MPPT controller would be a better choice in this
environment. That said, the HVAD is very suitable for systems that incorporate larger wind turbines and/or smaller
solar systems that are properly matched to their battery bank.
The HVAD excels when used in conjunction with a wind/hydro turbine to run diversion loads.
The HVAD is a diversion controller by design. A diversion controller is very well suited to wind and hydro systems
in that these energy sources need (or should) stay connected to the battery at all times, whereas solar can be
disconnected without problems. The HVAD takes “diversion” to a new level by incorporating the 3 stages, equalize,
configurable cycle times and many features not seen before in a diversion controller. The following section will
explain some of the settable features that allow the HVAD to excel as a diversion controller yet is used as a solar
disconnect controller as well.
1. Setting up the charge parameters. See the technical specifications pages for the factory defaults. If you
need to alter any charge settings, simply select the charge menu choice from the main menu and scroll though
the submenu to select and alter the values. There are very few limits placed on the values you set, other than
you cannot set a float set point higher than the bulk, or the bulk higher than double the battery system voltage
etc. Once you set or reset these settings, you should monitor the controller and see that these settings are
working to achieve the results you require.
The factory time setting for the absorption is 120 minutes. This value can be changed as required. This
timer is performance based. The microprocessor uses multiple algorithms to determine if during the last
minute the batteries actually realized a certain level of charging. The main consideration is whether the
controller was able to reach and hold the upper set point. If the performance during the last minute for the
Summary of Contents for C440-HVAD
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