Xantrex C12 Owner's Manual

C12 Charge/Load/Lighting Controller

Owner’s Manual

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March 2004
975-0130-01-01 Rev. B

Printed in China

Xantrex C12 Charge/ Load / Lighting Controller Owner’s Manual

Introducing the C12

The Xantrex Technology C12 charge/load controller is the finest small
system charge/load controller available and has many capabilities
previously either non-existent, or found only in separate products.

Numerous standard features maximize the performance of the system:

• Designed to meet the National Electric Code and other international
controller specifications. ETL certified for the U.S. (UL Standard
1741 (draft)), and Canada (CSA-C22.2 No. 14-M91 SEP 91).

• Electronic overload and short circuit protection with automatic and
manual reset ability. Increases the reliability of unattended systems
by eliminating blown fuses or tripped circuit breakers.

• Field adjustment of the setpoints is provided by rotary controls with
removable knobs to reduce the potential for setpoint tampering.
Includes calibrated scales for adjustment of the settings and
testpoints to verify setpoints using a digital meter (not required).

• Optional external plug-in temperature compensation sensor for
automatic adjustment of the charge controller setpoints to the
battery temperature. This UL requirement is also strongly
recommended for sealed batteries.

• Over-temperature protection of the electronic circuitry is provided by
reducing the charge rate. This improves the reliability of the C12
when used in very hot environments (over 113°F / 45°C ambient).

• Outdoor rain-tight powder coated enclosure for pole or wall
mounting.

• Multi-color LED with matching color label for mode/status indication.

• 2 year limited warranty

These instructions only apply to the C12 REV D or later.

Operating Modes

The model C12 charge/load controller can operate in one or more of
the following modes:

Photovoltaic Charge Control Mode with 3-stage

•
regulation and automatic or manual battery equalization cycle.

• DC Load Control Mode includes automatic low battery
disconnect with warning by flashing the loads. In manual mode the
reset switch allows one 10-minute “grace period” of load operation.

NITE-LITE Mode with automatic dusk detection and adjustable

•
time period from 10 minutes to 9.5 hours duration or dusk to dawn
operation with a 20 hour limit.

Photovoltaic Charge Control Mode

3-Stage Regulation

The C12 charge controller rapidly cycles the photovoltaic array on and
off to control the charging of the battery. The battery voltage will vary
during the charging process, as follows:

BULK—During this stage the PV array is allowed to charge at its

1.

full output. Once the voltage of the battery reaches the BULK
voltage setting, the controller goes to the next stage.

ABSORPTION—During this stage the voltage of the battery is

2.

held at the BULK voltage setting until a timer accumulates 1 hour.

3.

FLOAT—During this stage the voltage of the battery is held at

the FLOAT voltage setting. Full current from the PV array can still
be delivered to the loads during this stage.

If the voltage of the battery drops below the FLOAT setting for a
cumulative period of one hour, a new BULK or ABSORPTION cycle
will be triggered. This typically occurs during each night. If the battery
is full at the start of the day, it will receive only an ABSORPTION
charge for 1 hour and then be held at the FLOAT setting for the
remaining period of the day unless the battery is discharged.

This 3-stage charging process results in faster recharging of batteries
compared to on-off or constant voltage regulators. Faster recharging
increases the performance of the system by storing more of the PV
array’s limited output. The final FLOAT voltage setting reduces
gassing of the battery, minimizing watering requirements and ensuring
the complete recharge of the battery.

Automatic PV Array Night Disconnection

Each night the PV array is automatically disconnected from the battery
to prevent reverse leakage of power. This eliminates the need for a
blocking diode between the battery and the PV array. If you are using
thin-film or amorphous solar modules, diodes may still be required to
prevent damage from partial shading conditions. Check the
documentation provided for the requirements of your PV modules.

Equalization (Non-Sealed Batteries Only)

Approximately every month, the batteries may need to be "equalized"
(a fancy term for over-charged). Since the individual cells of the
battery are not identical, some cells may not be fully charged when the
charging process is completed. Or, if the batteries have been left
uncharged for periods of time, the plates will have sulfates on them. If
the sulfate remains on the plates for an extended period of time, it will
harden and seal off a percentage of the plate area, reducing the
capacity of the battery. By equalizing the batteries, the sulfate is
removed from the plates.

Additionally, batteries with liquid electrolyte may become stratified.
Stratification concentrates the sulfuric acid into the bottom of the cell
while the top becomes diluted. This corrodes the lower portion of the
plates, reducing battery life. Mixing of the electrolyte by the formation
of gas bubbles during the equalization process reduces stratification.

You can check if a battery needs to be equalized by two methods. If
you can measure the voltage of each individual cell, a variation of 0.05
volts between cells indicates an imbalance exists. If the battery
construction prevents measurement of the individual cell voltages, use
a hydrometer. If you can measure the specific gravity of each of the
battery cells, a variation of 0.020 is considered significant. Both
conditions may be corrected by an equalization charge.

A proper equalization charge will not damage a vented, liquid
electrolyte type battery. It may, however, cause significant electrolyte
usage and require that the battery be refilled with distilled water to the
correct level. This may be a problem with unattended systems in
remote areas that do not receive regular maintenance. Consult the
battery manufacturer for their recommendations.

CAUTION: Equalization should only be done with vented (not

sealed or maintenance free) lead acid, liquid electrolyte batteries.
The battery manufacturer should be consulted before attempting
to equalize any other type battery. Clean, distilled water will need
to be added to the battery AFTER the equalization process.

DC loads may need to be disconnected by turning off circuit
breakers or removing fuses before equalization to prevent
damage by the required higher voltages. Just turning off the DC
loads by its on/off switch may not provide protection.

WARNING: If the batteries are equipped with HYDROCAPS

(catalytic gas recombiner caps), they should be removed during
the equalization process. If hydrocaps are used, you should
disable automatic equalization to prevent possible damage.

The C12 includes both automatic and manual triggering of the
equalization process. Automatic equalization is enabled by removing
the jumper located on bottom right corner the circuit board next to the
reset switch (the default setting is disabled). An equalization charge,
(holding the voltage 1 volt above bulk for 2 hours) will occur every 30
days or once the system has reached the LVD level for a period of two
minutes or longer. The default setting is auto equalization disabled.

Manual equalization is not available when the C12 is used in the NITE­LITE mode because the reset switch provides a test function of the
loads instead (this only applies to the NITE-LITE mode).

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Manual Equalization

Manual equalization of the battery can be enabled pressing and
holding the reset switch until the LED indicator begins to alternate
between red and green. The equalization process will continue until
the batteries have been held above the bulk setting for two hours of
accumulated time. The battery voltage will be limited to 1 volt above
the BULK setting during this period. Once two hours have been
accumulated, the C12 will return to the FLOAT stage of the charging
process (with NiCad batteries the battery voltage is held at the BULK
setting for a two hour period before it returns to the float level).

To stop the equalization process, press and hold the reset switch until
the LED stops alternating between red and green. If the equalization
process was shorter than 1 hour, the C12 will continue with a BULK
charge cycle and then hold the battery at the BULK setting for one
hour (the absorption stage) before returning to the FLOAT setting.

During the equalization process the LED will alternate between red
and green and will not provide any other mode/status indication.

Manual equalization is not available when operating the controller in
the NITE-LITE mode. Pressing the reset switch in this mode provides
a test of the loads (the lights) for a period of two minutes.

Automatic Equalization

The C12 can automatically trigger an equalization charge every 30
days or after the voltage drops below the LVD setting for a period of
two minutes. The LED will indicate that the equalization process is
occurring only once the battery voltage has risen above the bulk
setting.

To enable automatic equalization, the jumper located at the bottom
right corner of the circuit board must be removed. The default setting
of the C12 is automatic equalization disabled.

To stop the equalization process, press and hold the reset switch on
the bottom of the C12 until the LED indicator stops alternating
between red and green. If the equalization process was shorter than 1
hour, the C12 will continue with a BULK charge cycle and then hold
the battery at the BULK setting for one hour (the absorption stage)
before returning to the FLOAT setting.

Electronic Overcurrent Protection

During operation, the C12 continuously monitors the current flowing
into and out of the battery. If the current exceeds 15 amps the
transistor switches are opened, stopping the flow of electricity. This
protects the loads and array wiring from short circuits and overloads.
The detection circuitry is faster than breakers or fuses—they will not
trip or blow when a fault occurs because the C12 will protect sooner.

The C12 will automatically attempt to restart the load 12 seconds after
the overcurrent condition was detected. If the overcurrent reoccurs
when the system is re-energized, it turns off again. A second attempt
to restart the system will occur after an additional 12 seconds. If this
fails, the C12 will try to restart the system every 15 minutes.

The reset switch on the bottom of the C12 allows the user to attempt a
manual restart at any time. When the controller is unable to
automatically restart the system, check the wiring and reduce the
loads connected. Allow for up to a 12-second delay after pressing the
reset switch for the restart to occur.

The current shunt which is used to measure the current flow is located
in the positive conductor of the circuit as required by UL Standard
1741 (draft). This allows you to use any combination of the negative
terminals, as they are all common to one another.

Temperature Compensation

The optional plug-in external temperature sensor automatically fine­tunes the charging process of the C12. If the temperature sensor is
installed, the regulation setpoints should be adjusted for a battery at
23°C/74°F. The C12 adjusts the BULK and FLOAT setpoints -0.03v
per °C for lead acid type batteries and -0.02v per °C for NiCad type
batteries.

If the temperature sensor is not installed, the setpoints should be
adjusted to account for the temperature of the battery during
operation. Seasonal adjustment of the setpoints may be necessary to
prevent battery damage and to ensure proper charging.

Xantrex C12 Charge/ Load / Lighting Controller Owner’s Manual

Over-temperature Protection

The temperature of the C12’s transistors is also continuously
monitored. This protects the charge controller from damage in high­temperature environments. If excessive temperatures are detected,
the charge control transistor is rapidly turned off and on to reduce the
charge rate. This will reduce the transistor temperature.

If the PV array current is reduced to zero and the over-temperature
condition continues, the load will be disconnected. Once the
temperature has dropped, the PV array and then the loads will be
reconnected.

The C12 is rated for 12 amps continuous at up to 45°C/113°F and 8
amps at up to 65°C/150°F.

Battery Loss Detection

If the battery is disconnected from the system while the PV array is
charging, the C12 will prevent damage to DC loads by a high voltage
condition (over 18 volts) by disconnecting the PV array. The C12 also
prevents oscillation of the system (on-off-on...) which is common with
other controllers when the battery has been disconnected but the PV
array remains connected.

DC Load Control Mode

The C12 includes a 12-amp load control to manage the discharging of
the battery. This prevents damage to the battery from over-discharge
during periods of poor weather or excessive loads.

The C12 load controller is unique in that it includes a warning flash of
the loads (off then on) to alert the user that the load will be turned off
after an additional 5 minute delay period. This gives the user an
opportunity to reduce the loads and extend operation of the system.

Once the load has been disconnected, the user is given a one time;
10-minute “grace” period of load operation immediately after the reset
switch has been pressed. This allows the user to operate critical loads
for a limited period. The small additional discharge of the battery will
not cause any harm.

Reconnection of the load is allowed once the battery voltage has
exceeded the Low Voltage Reconnect (LVR) setting. The default
setting of the C12 is manual reconnection (MANUAL) of the loads after
the system has reached the LVD state. Manual reconnect is selected
by turning the bottom knob fully counter-clockwise to MANUAL.

Automatic Reconnection

Automatic reconnection of the loads at the LVR setting can be enabled
by adjusting the bottom-most knob to the area marked as AUTO
RECON instead of the default MANUAL area.

In automatic reconnection mode, no warning flash of the loads is
provided. Pressing the reset switch does not provide the one time, 10
minute additional “grace period” of load operation included in the
manual reconnection mode.

The low voltage disconnect includes a 2 minute delay before
disconnecting the loads when the voltage drops below the LVD setting
when automatic reconnection is selected.

NITE-LITE Mode

The C12 can also be used to automatically control photovoltaic lighting
systems. Up to 12 amps of lights can be controlled by the C12.

The installation and reliability of the system is maximized by using the
PV array as the photocell to provide dusk and dawn detection. When
the PV array voltage drops below 3.5 volts for a period exceeding 60
seconds, the C12 turns on the lights. If the PV array voltage exceeds

3.5 volts for 60 seconds, the C12 turns off the lights. When the PV
array voltage exceeds 9 volts the C12 resets the NITE-LITE-TIME
period counter for the next day’s operation.

To activate the NITE-LITE mode, select a run duration setting by
adjusting the knob at the bottom of the circuit board labeled as NITE­LITE-TIME. The minimum run time is 10 minutes and the maximum is

9.5 hours (automatic reset is standard for the NITE-LITE mode).

If the voltage falls below the LVD setting for more than 2 minutes, the
lights will be turned off to prevent damage to the battery. The LVD will

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