MPPT Solar Charge Controller

User Manual

Models:
MAX-M2024
MAX-M3024
MAX-M4024
 Important Safety Instructions

Please save this manual for future review.

This manual contains safety, installation and operation for Maximum Power Point
Tracking (MPPT) MAX series controller ("the controller" as referred to in this manual).

General Safety Information

 Read carefully all the instructions and warnings in the manual before installation.

No user serviceable components inside the controller. DO NOT disassemble or

attempt to repair the controller.

 Mount the controller indoors. Prevent exposure to the elements and do not allow
water to enter the controller.

 Install the controller in a well ventilated -place. The controller’s heat sink may
become very hot during operation.

 It is suggested to install appropriate external fuses/breakers.

 Make sure to switch off all PV array connections and the battery fuse/breakers
before controller installation and adjustment.

 Power connections must remain tight to avoid excessive heating from loose
connection.
 CONTENTS

1. General Information........................................................................1
1.1 Overview..............................................1
1.2 Characteristics.........................................2
1.3 Designations of Controller Models .......2
1.4 Maximum Power Point Tracking Technology ...............2
1.5 Battery Charging Stage .................................4

2. Installation Instructions .................................................................7

2.1 General Installation Notes ...............................7
2.2 PV Array Requirements .................................7
2.3 Wire Size .............................................9
2.4 Mounting.............................................10
3. Operation.......................................................................................14
3.1 Button ...............................................14
3.2 Interface .............................................14
3.3 Setting...............................................16
4. Protections, Troubleshooting and Maintenance ........................20
4.1 Protection ............................................20
4.2 Troubleshooting.......................................21
4.3 Maintenance .........................................21
5. Technical Specifications ..............................................................23
Annex I Conversion Efficiency Curves ...........................................25
Annex II Dimensions ........................................................................28
 1. General Information

1.1 Overview
Based on common negative design and advanced MPPT control algorithm, with LCD
displaying running status, this product is artistic, economical and practical. Improving
the MPPT control algorithm further, it can minimize the maximum power point loss
rate and loss time, quickly track the maximum power point of the PV array and obtain
the maximum energy from solar modules under any conditions; and can increase the
ratio of energy utilization in the solar system by 10%-30% compared with a PWM
charging method. The limitation function of the charging power and current and
reducing charging power function automatic improve the stability which works even
connecting oversize PV modules and in high temperature, and increase the
professional protection chip for the communication port, further improving the
reliability and meeting the different application requirements.
With the adaptive three-stage charging mode based on a digital control circuit, the
series controllers can effectively prolong the life-cycle of batteries, significantly
improve the system performance and support all-around electronic protection
functions, including overcharging and over discharging protection to minimize
damages to components of the system caused by incorrect installation or system
failure at the utmost, and effectively ensure safer and more reliable operation of the
solar power supply system for a longer service time. This modular solar controller can
be widely used for different applications, e.g., Communication base stations,
household systems, and field monitoring, etc.

Features：
 Advanced MPPT technology, with efficiency no less than 99.5%
 Ultra-fast tracking speed and guaranteed trackingefficiency
 Advanced MPPT control algorithm to minimize the maximum power point loss
rate and loss time
 Wide MPP operating voltage range
 High quality components, perfecting system performance, with maximum
conversion efficiency of 98%
 Accurate recognition and tracking of multiple-peaks maximum power point
 International famous brands of ST and IR's components of high quality and low
failure rate are used, which can ensure the product’s servicelife
 Charging power and current limitation function
 Compatible with lead-acid and lithium-ion batteries
 Battery temperature compensation function
 Real-time energy statistics function
 Overheating power reduction function
 Multiple load work modes
 The communication port adopts professional protection chip, which can provide
5VDC power supply, and has over-current and short-circuit protection.

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 Full-load operation without any drop in capacity within the range of working
environment temperature
 Extensive electronic protection

1.2 Characteristics

Figure 1 Product Characteristics

❶ SELECT button ❻ RS485 communication interface

❷ RTS★ Interface ❼ Mounting Hole Φ5mm
❸ PV Terminals ❽ ENTER button
❹ Battery Terminals ❾ LCD
❺ Load Terminals
★If the temperature sensor is short-circuited or damaged, the controller will
charge or discharge at the default temperature setting of 25 ºC.

1.4 Maximum Power Point Tracking Technology

Due to the nonlinear characteristics of solar array, there is a maximum energy output
point (Max Power Point) on its curve. Traditional controllers, with switch charging
technology and PWM charging technology, can’t charge the battery at the maximum
power point, so can’t harvest the maximum energy available from PV array, but the

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solar charge controller with Maximum Power Point Tracking (MPPT) Technology can
lock on the point to harvest the maximum energy and deliver it to the battery.
The MPPT algorithm of our company continuously compares and adjusts the
operating points to attempt to locate the maximum power point of the array. The
tracking process is fully automatic and does not need user adjustment.
As the Figure 1-2, the curve is also the characteristic curve of the array, the MPPT
technology will ‘boost’ the battery charge current through tracking the MPP. Assuming
100% conversion efficiency of the solar system, in that way, the following formula is
established:
Input power (P PV)= Output power (P Bat )

Input voltage (VMpp ) *input current (IPV) =Battery voltage (VBat ) *battery current (IBat )

Normally, the VMpp is always higher than VBat, Due to the principle of conservation of
energy, the IBat is always higher than IPV. The greater the discrepancy between VMpp
&VBat, the greater the discrepancy between IPV& IBat. The greater the discrepancy
between array and battery, the bigger reduction of the conversion efficiency of the
system, thus the controller’s conversion efficiency is particularly important in the PV
system.
Figure 1-2 is the maximum power point curve, the shaded area is charging range of
traditional solar charge controller (PWM Charging Mode), it can obviously diagnose
that the MPPT mode can improve the usage of the solar energy resource. According
to our test, the MPPT controller can raise 20%-30% efficiency compared to the PWM
controller. (Value may be fluctuant due to the influence of the ambient circumstance
and energy loss.)

Figure 1-2 Maximum Power Point Curve

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In actual application, as shading from cloud, tree and snow, the panel maybe appear
Multi-MPP, but in actually there is only one real Maximum Power Point. As the below
Figure 1-3 shows:

Figure 1-3 Mutil-MPP Curve

If the program works improperly after appearing Multi-MPP, the system will not work
on the real max power point, which may waste most solar energy resources and
seriously affect the normal operation of the system. The typical MPPT algorithm,
designed by our company, can track the real MPP quickly and accurately, improvethe
utilization rate of the array and avoid the waste of resources.

1.5 Battery Charging Stage

The controller has a 3 stages battery charging algorithm (Bulk Charging, Constant
Charging and Float Charging) for rapid, efficient, and safe battery charging.

Figure 1-4 Battery changing stage Curve

A) Bulk Charging

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In this stage, the battery voltage has not yet reached constant voltage (Equalize or
Boost Voltage), the controller operates in constant current mode, delivering its
maximum current to the batteries (MPPT Charging).
B) Constant Charging
When the battery voltage reaches the constant voltage setpoint, the controller will start
to operate in constant charging mode, this process is no longer MPPT charging, and
in the meantime the charging current will drop gradually, the process is not the MPPT
charging. The Constant Charging has 2 stages, equalize and boost. These two stages
are not carried out constantly in a full charge process to avoid too much gas
precipitation or overheating of battery.
 Boost Charging

The Boost stage maintain 2 hours in default, user can adjust the constant time and
preset value of boost voltage according to demand.
The stage is used to prevent heating and excessive battery gassing.
 Equalize Charging

WARNING: Explosive Risk!

Equalizing flooded battery would produce explosive gases, so well
ventilation of battery box is recommended.
CAUTION: Equipment damage!
Equalization may increase battery voltage to the level that damages
sensitive DC loads. Verify that all load allowable input voltages are 11%
greater than the equalizing charging set point voltage.
CAUTION: Equipment damage!
Over-charging and excessive gas precipitation may damage the battery
plates and activate material shedding on them. Too high an equalizing
charge or for too long may cause damage.
Please carefully review the specific requirements of the battery used in the system.
Some types of batteries benefit from equalizing charge on a regular basis, which is
able to stir electrolyte, balance battery voltage and accomplish chemical reaction.
Equalizing charge increases battery voltage, higher than the standard complement
voltage, which gasifies the battery electrolyte.
The controller will equalize the battery on 28th each month. The constant equalization
period is 0~180 minutes. If the equalization isn’t accomplished in one-time, the
equalization recharge time will be accumulated until the set time is finished. Equalize
charge and boost charge are not carried out constantly in a full charge process to
avoid too much gas precipitation or overheating of battery.
NOTE:
1) Due to the influence of ambient circumstance or load working, the battery
voltage can’t be steady in constant voltage, controller will accumulate and
calculate the time of constant voltage working. When the accumulated time
reach to 3 hours, the charging mode will turn to Float Charging.

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2) If the controller time is not adjusted, the controller will equalize charge
battery once every month following the inner time.
C) Float Charging
After the Constant voltage stage, the controller will reduce charging current to Float
Voltage setpoint. This stage will have no more chemical reactions and all the charge
current transforms into heat and gas at this time. Then the controller reduces the
voltage to the floating stage, charging with a smaller voltage and current. It will reduce
the temperature of the battery and prevent the gassing and charging the battery
slightly at the same time. The purpose of Float stage is to offset the power
consumption caused by self consumption and small loads in the whole system, while
maintaining full battery storage capacity.
In Float charging stage, loads are able to obtain almost all power from solar panel. If
loads exceed the power, the controller will no longer be able to maintain battery
voltage in Float charging stage. If the battery voltage remains below the Recharge
Voltage, the system will leave Float charging stage and return to Bulk charging stage.

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2. Installation Instructions
2.1 General Installation Notes
 Please read the entire installation instructions to get familiar with the installation
steps before installation.

 Be very careful when installing the batteries, especially flooded lead-acid battery.
Please wear eye protection, and have fresh water available to wash and clean any
contact with battery acid.

 Keep the battery away from any metal objects, which may cause short circuit of the
battery.

 Explosive battery gases may come out from the battery during charging, so make
sure ventilation condition is good.

 Ventilation is highly recommended if mounted in an enclosure. Never install the

controller in a sealed enclosure with flooded batteries! Battery fumes from vented
batteries will corrode and destroy the controller circuits.

 Loose power connections and corroded wires may result in high heat that can melt
wire insulation, burn surrounding materials, or even cause fire. Ensure tight
connections and use cable clamps to secure cables and prevent them from swaying
in mobile applications.

 Lead-acid battery and lithium battery are recommended, other kinds please refer to
the battery manufacturer.

 Battery connection may be wired to one battery or a bank of batteries. The following
instructions refer to a singular battery, but it is implied that the battery connection
can be made to either one battery or a group of batteries in a battery bank.
 Multiple same models of controllers can be installed in parallel on the same battery
bank to achieve higher charging current. Each controller must have its own solar
module(s).

 Select the system cables according to 5A/mm2 or less current density in accordance
with Article 690 of the National Electrical Code, NFPA 70.

2.2 PV Array Requirements

(1) Serial connection (string) of PV modules
As the core component of PV system, controller could be suitable for various types of
PV modules and maximize converting solar energy into electrical energy. Accordingto
the open circuit voltage (Voc) and the maximum power point voltage (VMpp) of the
MPPT controller, the series number of different types PV modules can be calculated.
The below table is for reference only.

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MAX-M2024/3024/4024:
36 cell 48 cell 54 cell 60 cell
System Voc＜23V Voc＜31V Voc＜34V Voc＜38V
voltage
Max. Best Max. Best Max. Best Max. Best
12V 4 2 2 1 2 1 2 1
24V 4 3 2 2 2 2 2 2

72 cell Voc＜46V 96 cell Voc＜62V Thin-Film

System
Module
voltage Max. Best Max. Best Voc＞80V
12V 2 1 1 1 1
24V 2 1 1 1 1

NOTE: The above parameter values are calculated under standard test conditions
(STC (Standard Test Condition)：Irradiance 1000W/m2，Module Temperature 25℃，
Air Mass1.5.)
(2) Maximum PV array power
The MPPT controller has the function of current/power-limiting, that is, during the
charging process, when the charging current or power exceeds the rated charging
current or power, the controller will automatically limit the charging current or power to
the rated charging current or power, which can effectively protect the charging parts of
controller, and prevent damages to the controller due to the connection of some over-
specification PV modules. The actual operation of PV array is as follows:

Condition 1:
Actual charging power of PV array ≤ Rated charging power of controller

Condition 2:
Actual charging current of PV array ≤ Rated charging current of controller

When the controller operates under “Condition 1”or“ Condition 2”, it will carry out the
charging as per the actual current or power; at this time, the controller can work at the
maximum power point of PV array.

WARNING: When the power of PV is not greater than the rated charging
power, but the maximum open-circuit voltage of PV array is more than
50(MAX12**)/96V(MAX24**) (at the lowest environmental temperature),
the controller may be damaged.

Condition 3:
Actual charging power of PV array＞Rated charging power of controller

Condition 4:
Actual charging current of PV array＞Rated charging current of controller

When the controller operates under “Condition 3”or“Condition 4”，it will carry out the
charging as per the rated current or power.

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 WARNING: When the power of PV module is greater than the rated
charging power, and the maximum open-circuit voltage of PV array is more
than 96V (at the lowest environmental temperature), the controller may be
damaged.

According to “Peak Sun Hours diagram”, if the power of PV array exceeds the rated
charging power of controller, then the charging time as per the rated power will be
prolonged, so that more energy can be obtained for charging the battery. However, in
the practical application, the maximum power of PV array shall be not greater than 1.5
x the rated charging power of controller. If the maximum power of PV array exceeds
the rated charging power of controller too much, it will not only cause the waste of PV
modules, but also increase the open-circuit voltage of PV array due to the influence of
environmental temperature, which may make the probability of damage to the
controller rise. Therefore, it is very important to configure the system reasonably. For
the recommended maximum power of PV array for this controller, please refer to the
table below:

Model Rated Charge Rated Charge Max. PV Array Max. PV open

Current Power Power circuit voltage
260W/12V 390W/12V
MAX-M2024 20A
520W/24V 780W/24V
92V①
390W/12V 580W/12V
MAX-M3024 30A 780W/24V 1170W/24V 100V②
520W/12V 780W/12V
MAX-M4024 40A 1040W/24V 1560W/24V
①At 25℃ environmenttemperature
②At minimum operating environment temperature

2.3 Wire Size

The wiring and installation methods must conform to all national and local electrical
code requirements.

 PV Wire Size

Since PV array output can vary due to the PV module size, connection method or
sunlight angle, the minimum wire size can be calculated by the Isc＊ of PV array.
Please refer to the value of Isc in the PV module specification. When PV modules
connect in series, the Isc is equal to a PV modules Isc. When PV modules connect in
parallel, the Isc is equal to the sum of the PV module’s Isc. The Isc of the PV array
must not exceed the controller’s maximum PV input current. Please refer to the table
as below:
NOTE: All PV modules in a given array are assumed to be identical.
＊Isc=short circuit current(amps) Voc=open circuit voltage.

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 Model Max. PV input current Max. PV wire size＊
MAX-M2024 20A 6mm2/10AWG
MAX-M3024 30A 10mm2/8AWG
MAX-M4024 40A 16mm2/6AWG

＊These are the maximum wire sizes that will fit the controller terminals.
CAUTION: When the PV modules connect in series, the open circuit
voltage of the PV array must not exceed 92V at 25℃ environment
temperature.

 Battery and Load Wire Size

The battery and load wire size must conform to the rated current, the reference size
as below:

Rated Rated
Batterywire Load wire
Model charge discharge
size size
current current
MAX-M2024 20A 20A 6mm2/10AWG 6mm2/10AWG
MAX-M3024 30A 30A 10mm2/8AWG 10mm2/8AWG

MAX-M4024 40A 40A 16mm2/6AWG 16mm2/6AWG

CAUTION: The wire size is only for reference. If there is a long distance between the
PV array and the controller or between the controller and the battery, larger wires can
be used to reduce the voltage drop and improve performance.

CAUTION: For the battery, the recommended wire will be selected

according to the conditions that its terminals are not connected to any
additional inverter.

2.4 Mounting
WARNING: Risk of explosion! Never install the controller in a sealed
enclose with flooded batteries! Do not install in a confined area where
battery gas can accumulate.

WARNING: Risk of electric shock! When wiring the solar modules, the PV
array can produce open circuit voltages in excess of 100V when in
sunlight.

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 CAUTION：The controller requires at least 150mm of clearance above
and below for proper air flow. Ventilation is highly recommended if
mounted in an enclosure.

Installation Procedure:

Figure 2-1 Mounting

Step 1: Determination of Installation Location and Heat-dissipation Space
Determination of installation location: The controller shall be installed in a place with
sufficient air flow through the radiators of the controller and a minimum clearance of
150 mm from the upper and lower edges of the controller to ensure natural thermal
convection. Please see Figure 2-1: Mounting

CAUTION: If the controller is to be installed in an enclosed box, it is

important to ensure reliable heat dissipation through the box.

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Figure 2-2 Schematic of wiring diagram

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Step 2：Connect the system in the order of ❶battery  ❷ load ❸PV array in
accordance with Figure 2-2,”Schematic Wiring Diagram” and disconnect the system in
the reverse or der ❸❷❶.

CAUTION: While wiring the controller do not close the circuit breaker or
fuse and make sure that the leads of "+" and "-" poles are connected
correctly.

CAUTION: A fuse which current is 1.25 to 2 times the rated current of the
controller, must be installed on the battery side with a distance from the
battery not greater than 150 mm.

CAUTION: If the controller is to be used in an area with frequent lightning

strikes or unattended area, it must be installed an external surge arrester.

CAUTION: If an inverter is to be connected to the system, connect the

inverter directly to the battery, not to the load side of the controller.

Step 3：Grounding
MAX series is a common-negative controller, where all the negative terminals of PV
array, battery and load can be grounded simultaneously or any one of them will be
grounded. However, according to the practical application, all the negative terminals of
PV array, battery and load can also be ungrounded, but the grounding terminal on its
shell must be grounded, which may effectively shield the electromagnetic interference
from the outside, and prevent some electric shock to human body due to the
electrification of the shell.
CAUTION: For common-negative system, such as motorhome, it is
recommended to use a common-negative controller; but if in the
common-negative system, some common-positive equipment are used,
and the positive electrode is grounded, the controller may be damaged.
Step 4：Connect accessories

 Connect the remote temperature sensor cable (model: RTS-MAX1.0)

Remote Temperature Sensor

Temperature Sensor
Cable (Optional)
（Model:TS-MAX1.0A） （Model:RTS-MAX1.0B）

Connect one end of the remote temperature sensor cable

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to the interface ③ and place the other end close to the battery.

CAUTION: If the remote temperature sensor is not connected to the

controller,, the default setting for battery charging or discharging
temperature is 25 °C without temperature compensation.

 Connect the accessories for RS485 communication

Refer to chaper3.3 “Setting”

CAUTION: If the remote temperature sensor is not connected to the

controller,, the default setting for battery charging or discharging
temperature is 25 °C without temperature compensation.

Step 5：Powered on the controller

Closing the battery fuse will switch on the controller. Then check the status of the
battery indicator (the controller is operating normally when the indicator is lit in green).
Close the fuse and circuit breaker of the load and PV array. Then the system will be
operating in the preprogrammed mode.

CAUTION: If the controller is not operating properly or the battery indicator

on the controller shows an abnormality, please refer to 4.2
“Troubleshooting”.

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3. Operation

3.1 Button
Mode Note

Load ON/OFF In load manual mode, it can turn the load On/Off of the load via
the “ENTER” button.
Clear Fault Press the “ENTER” button.
Browsing Mode Press the “SELECT” button.
Press the “ENTER” button. and hold on 5s to enter the setting
mode
Setting Mode Press the “SELECT” button. to set the parameters,
Press the “ENTER” button. to confirm the setting parameters or
exit the setting mode automatically after 10s.

3.2 Interface

1） Icon
Item Icon Status

PV array Day

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 Night

No charging

Charging

PV Voltage, Current, Power

Battery capacity, In Charging

Battery
Battery Voltage, Current, Temperature

Battery Type

Load ON

Load
Load OFF

Load Voltage, Current, Load mode

2） Fault Indication

Status Icon Description

Battery over Battery level shows empty, battery frame blink,

discharged fault icon blink

Battery over Battery level shows full, battery frame blink, fault
voltage icon blink

Battery over Battery level shows current value, battery frame

temperature blink, fault icon blink

Load failure Load overload① ,Load short circuit

①When load current reaches1.02-1.05 times 1.05-1.25 times, 1.25-1.35 times and
1.35-1.5 times more than nominal value, controller will automatically turn off loads in
50s, 30s,10s and 2s respectively.

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3） Browse interface

3.3 Setting
1)Clear the generated energy
Operation:
Step 1: Press the “ENTER” button and hold 5s under the PV power interface and
the value is flashing.
Step 2: Press the “ENTER” button to clear the generated energy..
2)Switch the battery temperatureunit
Press the “ENTER” button and hold 5s under the battery temperature interface.
3)Battery type
①Battery type

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 Item Lead-acid battery Lithium battery
1 Sealed(default) LiFePO4(4s/12V; 8s/24V)
2 Gel Li(NiCoMn)O2 (3s/12V; 6s/24V)
3 Flooded User(9～34V)
4 User(9～17V/12V; 18～34V/24V)

CAUTION: When the default battery type is selected, the battery voltage
control parameters will be set by default and can’t be changed. To change
these parameters, select "User" battery type.

Operation:
Step1: Press the “ENTER” button and hold 5s under the battery voltage interface.
Step2: Press the “SELECT” button when the battery type interface is flashing.
Step3: Press the “ENTER” button to confirm the battery type.

CAUTION：Please refer to chapter③ for the battery control voltage, when

the battery type is User.

②Battery Voltage Control Parameters

Below parameters are in 12V system at 25 ºC, please double the values in 24V
system
Batterytype
Sealed Gel Flooded User
Voltage
Over Voltage Disconnect 16.0V 16.0V 16.0V 9～17V
Voltage
Charging Limit Voltage 15.0V 15.0V 15.0V 9～17V
Over Voltage Reconnect 15.0V 15.0V 15.0V 9～17V
Voltage
Equalize Charging Voltage 14.6V —— 14.8V 9～17V
Boost Charging Voltage 14.4V 14.2V 14.6V 9～17V
Float Charging Voltage 13.8V 13.8V 13.8V 9～17V
Boost Reconnect Charging 13.2V 13.2V 13.2V 9～17V
Voltage
Low VoltageReconnect
12.6V 12.6V 12.6V 9～17V
Voltage
Under VoltageWarning 12.2V 12.2V 12.2V 9～17V
Reconnect Voltage
Under VoltageWarning 12.0V 12.0V 12.0V 9～17V
Voltage
Low VoltageDisconnect 11.1V 11.1V 11.1V 9～17V
Voltage
Discharging Limit Voltage 10.6V 10.6V 10.6V 9～17V
Equalize Duration 120 min —— 120 min 0～180 min
Boost Duration 120 min 120 min 120 min 10～180 min

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 CAUTION: Due to diversification of lithium battery types, its control voltage
shall be confirmed with the engineer.

③ User settings
(1)Setting the control voltage value
 The following rules must be observed when modifying the parameter values in
User for lead-acid battery.
Ⅰ . Over Voltage Disconnect Voltage > Charging Limit Voltage ≥ Equalize
Charging Voltage ≥ Boost Charging Voltage ≥ Float Charging Voltage > Boost
Reconnect Charging Voltage.
Ⅱ. Over Voltage Disconnect Voltage > Over Voltage Reconnect Voltage
Ⅲ. Low Voltage Reconnect Voltage > Low Voltage Disconnect Voltage ≥
Discharging Limit Voltage.
Ⅳ.Under Voltage Warning Reconnect Voltage > Under Voltage Warning Voltage
≥ Discharging Limit Voltage.
Ⅴ. Boost Reconnect Charging voltage > Low Voltage Disconnect Voltage.
 The following rules must be observed when modifying the parameter values in
User for lithium battery.
Ⅰ. Over Voltage Disconnect Voltage>Over charging protection
voltage(Protection Circuit Modules(PCM))+0.2V※；
Ⅱ. Over Voltage Disconnect Voltage>Over Voltage Reconnect Voltage＝
Charging Limit Voltage ≥ Equalize Charging Voltage＝Boost Charging Voltage
≥ Float Charging Voltage>Boost Reconnect Charging Voltage；
Ⅲ. Low Voltage Reconnect Voltage>Low Voltage Disconnect Voltage ≥
Discharging Limit Voltage；
Ⅳ.Under Voltage Warning Reconnect Voltage>Under Voltage Warning Voltage≥
Discharging Limit Voltage；
Ⅴ. Boost Reconnect Charging voltage>Low Voltage Disconnect Voltage.；
Ⅵ.Low Voltage Disconnect Voltage ≥ Over discharging protection voltage
(PCM)+0.2V※；
WARNING: The required accuracy of PCM shall be at least 0.2V. If the
deviation is higher than 0.2V, the manufacturer will assume no liability for
any system malfunction caused by this.

4) Local load mode

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Operation:
Step1: Press the “ENTER” button and hold on 5s under the load mode interface.
Step2: Press the “SELECT” button when the load mode interface is flashing.
Step3: Press the “ENTER” button to the load mode..

NOTE：Please refer to 4.2 for the load working modes.

①Load working mode
1** Timer 1 2** Timer 2
100 Light ON/OFF 2n Disabled
101 Load will be on for 1 hour 201 Load will be on for 1 hour
since sunset before sunrise
102 Load will be on for 2 hours 202 Load will be on for 2 hours
since sunset before sunrise
103 203
～ Load will be on for 3 ～ 13 ～ Load will be on for 3 ～ 13
113 hours since sunset 213 hours before sunrise

114 Load will be on for 14 hours 214 Load will be on for 14 hours
since sunset before sunrise
115 Load will be on for 15 hours 215 Load will be on for 15 hours
since sunset before sunrise
116 Test mode 2n Disabled
117 Manual mode(Default load 2n Disabled
ON)
CAUTION: Please set Light ON/OFF, Test mode and Manual mode via
Timer1. Timer2 will be disabled and display "2 n ".

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4. Protections, Troubleshooting and Maintenance
4.1 Protection
When the charging current or power of the PV array exceeds its rated current or
PV Over power, it will be charged at the rated current or power.
Current/power NOTE: When the PV modules are in series, ensure that the open-circuit
voltage of the PV array does not exceed the "maximum PV open-circuit
voltage" rating. Otherwise the controller may be damaged.

PV Short Circuit When not in PV charging state, the controller will not be damaged in case of a short-
circuiting in the PV array.

When the polarity of the PV array is reversed, the controller may not be damaged
and can continue to operate normally after the polarity is corrected.
PV Reverse Polarity NOTE: If the PV array is reverse connected to the controller,1.5 times rated
controller powr (watts)from the PV array, will damage the controller.

Night Reverse
Prevents the battery from discharging through the PV module at night.
Charging

Battery Reverse Fully protected against battery reverse polarity; no damage to the controller
Polarity will result. Correct the miswire to resume normal operation.

When the battery voltage reaches the over voltage disconnect voltage, it will
Battery Over Voltage automatically stop battery charging to prevent battery damage caused by over-
charging.
When the battery voltage reaches the low voltage disconnect voltage, it will
Battery Over
Discharge automatically stop battery discharging to prevent battery damage caused by over-
discharging. (Any controller connected loads will be disconnected. Loads directly
connected to the battery will not be affected and may continue to discharge the
battery.)
The controller can detect the battery temperature through an external temperature
Battery Overheating
sensor. The controller stops working when its temperature exceeds 65 °C and
begins working when its temperature is below 55 °C.
When the temperature detected by the optional temperature sensor is lower than
Lithium Battery Low
the Low Temperature Protection Threshold(LTPT), the controller will stop charging
Temperature and discharging automatically. When the detected temperature is higher than the
LTPT, the controller will be working automatically (The LTPT is 0 °C by default and
can be set within the range of 10 ~ -40 °C).
When the load is short circuited (The short circuit current is ≥ 4 times the rated
Load Short Circuit controller load current), the controller will automatically cut off the output. If the
load reconnects the output automatically five times (delay of 5s, 10s, 15s, 20s,
25s), it needs to be cleared by pressing the Load button, restarting the controller or
switching from Night to the Day (nighttime > 3 hours).
When the load is overloading (The overload current is ≥ 1.05 times the rated load
Load Overload current), the controller will automatically cut off the output. If the load reconnects
automatically five times (delay of 5s, 10s, 15s, 20s, 25s), it needs to be cleared by
pressing the Load button restarting the controller, switching from Night to Day
(nighttime > 3 hours).
Controller The controller is able to detect the temperature inside the battery through an
Overheating★ optional remote sensor. The controller stops working when its temperature
exceeds 85 °C and begins to working when its temperature is below 75 °C.
The internal circuitry of the controller is designed with Transient Voltage
TVS High Voltage
Transients Suppressors (TVS) which can only protect against high-voltage surge pulses with
less energy. If the controller is to be used in an area with frequent lightning strikes,
it is recommended to install an external surge arrester.

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 ★When the internal temperature is 81℃, the reducing power charging mode which
reduce the charging power of 5%,10%,20%,40% every increase 1 ℃is turned on. If
the internal temperature is greater than 85℃, the controller will stop charging. But
while the temperature decline to be below 75 ºC, the controller will resume.

4.2 Troubleshooting
Possible reasons Faults Troubleshooting
Charging LED indicator off during Confirm that PV and battery
PV array
daytime when sunshine falls on PV wire connections are correct
disconnection
modules properly and tight
Battery voltage Please check the voltage of
Wire connection is correct, the
is lower than battery. At least 8V voltage to
8V controller is not working. activate the controller.

Battery level shows Check if battery voltage is

Battery over full, battery frame higher than OVD(overvoltage
voltage disconnect voltage), and
blink, fault icon blink
disconnect the PV.

When the battery voltage is

Battery over Battery level shows restored to or above LVR(low
discharged empty, battery frame voltage reconnect voltage), the
blink, fault icon blink load will recover

The controller will

Battery level shows automatically turn the system
Battery off. But while the temperature
empty, battery frame
Overheating decline to be below 55 ºC, the
blink, fault icon blink
controller will resume.
①Please reduce the number
of electric equipments.
Load Overload ②Restart the controller.
1. The load is no output
2. ③wait for one night-day cycle
(night time>3 hours).
①Check carefully loads
connection, clear the fault.
Load Short ②Restart the controller.
Circuit Load and fault icon blink
③wait for one night-day cycle
(night time>3 hours).

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4.3 Maintenance
The following inspections and maintenance tasks are recommended at least two
times per year for best performance.
 Make sure controller firmly installed in a clean and dry ambient.
 Make sure no block on air-flow around the controller. Clear up any dirt and
fragments on radiator.
 Check all the naked wires to make sure insulation is not damaged for serious
solarization, frictional wear, dryness, insects or rats etc. Repair or replacesome
wires if necessary.
 Tighten all the terminals. Inspect for loose, broken, or burnt wire connections.
 Check and confirm that LED is consistent with required. Pay attention to any
troubleshooting or error indication .Take corrective action if necessary.
 Confirm that all the system components are ground connected tightly and
correctly.
 Confirm that all the terminals have no corrosion, insulation damaged, high
temperature or burnt/discolored sign, tighten terminal screws to the suggested
torque.
 Check for dirt, nesting insects and corrosion. If so, clear up in time.

Check and confirm that lightning arrester is in good condition. Replace a new
one in time to avoid damaging of the controller and even other equipments.
WARNING：Risk of electric shock!
Make sure that all the power is turned off before above operations, and
then follow the corresponding inspections and operations.

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5. Technical Specifications
Electrical Parameters
Item MAX-M2024 MAX-M3024 MAX-M4024
System nominal ①
12/24VDC Auto
voltage
Rated charge current 20A 30A 40A
Rated discharge
20A 30A 40A
current
Battery voltage
8～32V
range
②
Max. PV open 100V
③
circuit voltage 92V
MPP voltage range (Battery voltage +2V) ～72V
260W/12V 390W/12V 520W/12V
Max. PV input power
520W/24V 780W/24V 1040W/24V
Self-consumption ≤12mA
Discharge circuit
≤0.23V
voltage drop
Temperature
compensate -3mV/℃/2V (Default)
④
coefficient
Grounding Common negative
RS485 interface 5VDC/100mA
LCD backlight time 60S (Default)
①When a lead-acid battery is used, the controller hasn’t the low temperature protection.
②At minimum operating environment temperature
③At 25℃ environment temperature
④When a lithium-ion battery is used, the system voltage can’t be identified automatically.

Environmental Parameters
Working environment temperature◆ -25℃～+50℃(100% input and output)
Storage temperature range -20℃～+70℃
Relative humidity ≤95%, N.C.
Enclosure IP30
◆ The controller can full load working in the working environment temperature, When
the internal temperature is 81℃, the reducing power charging mode is turned on.
Refer to P24.

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Mechanical Parameters
Item MAX-M2024 MAX-M3024 MAX-M4024
Dimension 220x154x 52mm 228x164x55mm 252x180x63mm
Mounting
dimension 170x145mm 170x164mm 210x171mm
Mounting
Φ5mm
hole size
2
Terminal 6AWG(16mm ) 6AW G(16mm2) 6AWG(16mm2)
Recommende
10AWG(6mm2) 8AW G(10mm2) 6AWG(16mm2)
d cable
Weight 0.94kg 1.26kg 1.65kg

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Annex I Conversion Efficiency Curves
Illumination Intensity: 1000W/m2 Temp: 25ºC

Model: MAX-M2024
1. Solar Module MPP Voltage(17V, 34V) / Nominal System Voltage(12V)

2. Solar Module MPP Voltage(34V,45V,68V) / Nominal System Voltage(24V)

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Model: MAX-M3024
1. Solar Module MPP Voltage(17V, 34V) / Nominal System Voltage(12V)

2. Solar Module MPP Voltage(34V,45V,68V) / Nominal System Voltage(24V)

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Model: MAX-M4024
1. Solar Module MPP Voltage(17V, 34V) / Nominal System Voltage(12V)

2. Solar Module MPP Voltage(34V,45V,68V) / Nominal System Voltage(24V)

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Annex II Dimensions
MAX-M2024 (Unit: mm)

28

28
MAX-M3024 (Unit: mm)

29

29
MAX-M4024 (Unit: mm)

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Any changes without prior notice! Version number: 1.0

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