Redarc LFP2420-LV User manual

In-vehicle 24V LiFePO4
Battery Charger
LFP2420 / LFP2420-LV

1
THE LFP2420(-LV)
The LFP series In-vehicle Battery Chargers feature technology designed to charge your Lithium
Iron Phosphate (LiFeP04) batteries to their optimal level, regardless of their size. By providing
a unique charging prole, the LFP series In-Vehicle Battery Chargers are able to achieve and
maintain an optimal charge in your auxiliary battery, at all times.
The LFP series In-vehicle Battery Chargers also feature a Maximum Power Point Tracking (MPPT)
solar regulator, allowing you to deliver the maximum amount of power from your solar panels to
your auxiliary battery.
WARNING & SAFETY INSTRUCTIONS
Do NOT disassemble the LFP2420(-LV) - the internal circuitry contains hazardous voltages.
Attempting to service the unit yourself may result in electric shock or re and will void the unit
warranty.
Do NOT use the LFP2420(-LV) to charge non-rechargeable batteries. Doing so may result in harm
to the user and/or damage to the LFP2420(-LV).
This appliance is not intended for use by persons (including children) with reduced physical,
sensory or mental capabilities, or lack of experience and knowledge, unless they are supervised
or have been instructed on how to use the appliance by a person responsible for their safety.
Children should be supervised to ensure that they do not play with the appliance.
Only use the LFP2420(-LV) for charging REDARC approved Lithium Iron Phosphate type 24V
batteries that feature an inbuilt battery management system with under and over voltage
protection and cell balancing functions.
Check the manufacturer’s data for your battery and ensure the maximum voltage of the
LFP2420(-LV) does not exceed the manufacturer’s recommended maximum charging voltage.
Ensure that the battery’s management system is capable of allowing the battery to be charged
with 20A. Please contact REDARC if you are unsure if your battery is compatible.
The LFP2420(-LV) will achieve best results when proper battery maintenance is regularly
performed.
SAL.FOR.Instruction Manual.LFP2420 Version 3

2
CONTENTS
Table of Contents Page
Warnings and Safety Instructions 01
Contents 02
Specifications 02
1 Product Function 03
1. Display Panel 03
2. Charging Algorithm 04
3. Turn On/Off Thresholds 04
4. Error Codes 05
2 Installation 05
1. RED wire - Input Source Positive 05
2. BLUE wire - Source Select 06
3. ORANGE wire - Not Used 07
4. BROWN wire - Auxiliary Battery Positive 07
5. BLACK wire - Common Ground 07
6. GREEN wire - Optional External LED Indication 07
7. Cable Sizing 08
8. Wiring 08
9. RK1260 Relay Kit 11
3 Troubleshooting 12
4 Frequently Asked Questions 13
5 Two Year Warranty 14
Specifications
Part Number LFP2420(-LV)
Continuous Current Rating 20A
Input Fuse Rating 12V/24V* 60A/40A (Not supplied)
Output Fuse Rating 30A (Not supplied)
Output Power 600W
DC Input Voltage Range* 9-32V
Solar Panel Open Circuit Voltage 17.5V-32.0V
Battery Type LiFePO4
Absorption Stage Voltage level 28.8V
Float Stage Voltage level 27.2V
No Load Current <100mA
Standby Current <8mA
Ambient Temperature -20°C to +80°C
Minimum O/P Battery Volts 0.1V
Weight 680g
Dimensions 150x120x37mm
Warranty 2 years
Standards CE, C-Tick, AS/NZS CISPR11:2004
*24V input applicable for LFP2420 only

3
1 PRODUCT FUNCTION
The LFP2420(-LV) is a three stage, 24V DC-DC battery charger that operates from an
alternator input of 12V nominal or from a 12V nominal solar panel input. The LFP2420
will also charge from an alternator input of a 24V nominal vehicle. The input voltage of
the LFP2420(-LV) can be above, below or equal to the output voltage making it ideal for
charging an auxiliary 24V battery where the distance from the main battery may cause a
signicant voltage drop. The LFP2420(-LV) is also designed to isolate the main battery from
the auxiliary battery, to avoid over-discharging the main battery.
1.1 Display Panel
The front panel features 4 LEDs to display the charge mode and charge status.
LED State ‘Charge Mode’ LED ‘Charge Status’ LED
Off Unit has no Power Output is off
Blinking Unit is in Standby Unit is supplying power
On Unit is on and can supply power
When blinking, the ash duty-cycle of the ‘Charge Status’ LED will increase to
reect the amount of current being supplied - If the LED is ON solid, the unit is
supplying full power.
Figure 1.1 - The LFP2420(-LV) Front Panel

4
1 PRODUCT FUNCTION
1.2 Charging Algorithm
When the Charger is turned on, it will move into the Boost stage. The Boost stage
maintains a constant current until the battery voltage reaches its Absorption Voltage.
The current in Boost stage may vary during operation in order to maintain safe
operating temperature, or to limit the difference between input and output voltages.
The Charger will then move to Absorption stage which maintains a constant voltage
level for a predetermined period of time or until the current being drawn by the
output battery drops to less than 4A for 30 seconds; after which the Charger will
enter Float stage.
Float stage maintains 27.2V for LiFePO4on the output battery, keeping the battery
topped up. This counteracts the battery’s self discharging or loads applied to the
battery. When the battery loses charge, the Charger will move back into the Boost
stage.
1.3 Turn On/Off Thresholds
12V
LFP2420
12V
LFP2420-LV
Solar
All Models
24V*4
LFP2420
Input
Open Circuit
Low voltage
conditions *2
Turn ON above 13.2V 12.0V 17.5V 26.4V
Turn OFF below 12.7V 11.9V 17.2V 25.4V
Input
Loaded Low
voltage
conditions*3
Turn OFF
instantly below 8V 17V
Turn OFF after
20 secs below 9V 18V
Input
Over voltage
shutdown
Turn ON below 15.5V 32V 32V
Turn OFF
instantly above 16V 32.5V 32.5V
Turn OFF after
20 secs above 15.6V 32.2V 32.1V
Output
Under voltage
shutdown
Shutdown if Output Battery < 0.1V
*1 Voltages Specied are ±100mV
*2 Tested every 100 Seconds.
*3 Constantly tested.
*4 ‘LV’ Versions not suitable for use in 24V vehicles

5
1 PRODUCT FUNCTION
1.4 Error Codes
In the event of a fault with the unit installation, either battery or solar panel, ALL
the LEDs on the unit will ash to indicate the fault type. Flashing sequences are
described in the table below.
LED State Description
1 ash (1 ash followed by 3.5 second off) Internal Hardware Fault
2 ash (2 ash followed by 3.5 second off) Reserved
3 ash (3 ash followed by 3.5 second off) Unit over temp fault
4 ash (4 ash followed by 3.5 second off) Output Battery Fault (Volts too high) /
Solar Panel connected reverse polarity
5 ash (5 ash followed by 3.5 second off) Input under voltage (Battery)
6 ash (6 ash followed by 3.5 second off) Input over voltage (Battery or Solar panel)
7 ash (7 ash followed by 3.5 second off) Reverse polarity
NOTE: The unit will operate optimally below 55°C with good airflow. At higher
temperatures the unit will de-rate output current.
NOTE: Appropriate connections must be made to the wires with a continuous current
rating of at least 40A for the LFP2420(-LV). Failure to do so may cause damage to the
unit and vehicle.
2 INSTALLATION
Mount the unit to a at surface close to the auxiliary
battery and away from any heat sources. The
LFP2420(-LV) has 6 wires and should be installed as
described over the following pages.
2.1 RED wire - Input Source Positive
The RED wire should be connected to the positive input
from the source - this can be either from a vehicle’s
starter battery or from a solar panel.
Appropriate size fuses should be used as per the
specications table on page 2.
OR
Start
Battery
Red Wire
Midi
Fuse
Red Wire
12v
Solar
Panel

6
2 INSTALLATION
2.2 BLUE wire - Source Select
The BLUE wire is provided to select whether the unit is charging from a vehicle
input or from a solar panel. This wire is monitored at all times.
2.1.1 Alternator Input
To charge from an alternator, the BLUE ‘Source Select’
wire must be connected to the vehicle ignition.
When connected in this way, the charger will only
charge the auxiliary battery when the vehicle ignition
is ON, guaranteeing that the charger will not drain the
input battery.
For standard (non ‘LV’) models, the BLUE wire may be
permanently connected to the Input Source Positive
supply and the charger will only charge when the
alternator is running. This is not suitable for the
LFP2420-LV.
2.1.2 Solar Input
The LFP2420 is also capable of charging the auxiliary
battery from a Solar source. The unit will accept an
input directly from an unregulated 12V nominal solar
panels and act as a MPPT Solar Regulator. To select
the Solar charging mode, the BLUE ‘Source Select’
wire can either be left disconnected or connected to
GROUND.
OR
Blue Wire
Not
Connected
Blue Wire
OR
Vehicle
Ignition
non-‘LV’
models only
All models
Blue Wire
Blue Wire
Red Wire
Input
Source
Positive
Midi
Fuse

7
2 INSTALLATION
2.3 ORANGE wire - Not Used
The ORANGE wire is not used on the LFP series
chargers. It should be left disconnected.
2.4 BROWN wire - Auxiliary Battery Positive
The BROWN wire should be connected to
the auxiliary battery’s positive terminal. This
should be a maximum of 1 metre in cable
length from the battery.Appropriate size fuses
should be used as per the specications table
on page 2.
2.5 BLACK wire - Common Ground
The BLACK wire should be connected to a ground
point that is common to both the Start battery (or the
Solar Input Ground wire) and the Auxiliary battery to
be charged. This point may be on the chassis of the
vehicle, on the chassis of the trailer/camper/caravan
or directly wired to both batteries, depending on your
installation requirements.
2.6 GREEN wire - Optional External LED Indication
The GREEN wire is provided to optionally connect an
external indicator LED which can be mounted away
from the unit (for example on the vehicle’s dashboard).
Connect the positive lead of the LED to the green wire,
and the negative lead to the common ground. No
external resistors are required.
The External LED will be ON when the unit is charging
and OFF when the unit is in standby mode or has no
power. Note: This output is not suitable for running a
globe.
Green Wire
Optional
LED
Not
Connected
Orange Wire
Brown Wire
Auxiliary
Battery
Fuse
Black Wire

8
2 INSTALLATION
2.7 Cable sizing
Below is a table outlining the required cable size for a given cable install length.
Always choose a wire diameter equal to or greater than what is specied below.
Cable Install Length
(m)
Recommended Wire Size
(mm²)
Closest
(BAE, B&S, AWG)
1 - 5 13.56 6
5 - 9 20.28 4
2.8 Wiring
The heavy gauge wires on the LFP2420(-LV) unit carry peak currents of up to
40Amps and it is important to make a good, low resistance, electrical connection
that will not degrade over time. Failure to make a good, reliable contact may
result in breakdown of the wire insulation and cause a short circuit, or worst case
a re. We recommend that this activity be undertaken by an appropriately trained
person.
REDARC recommends using a soldered butt splice crimp connection that is
covered with heatshrink. See Figure 2.1. REDARC does not recommend using
standard red/ blue/yellow blade connections as they are not rated for either the
current required or gauge of wire supplied on the unit.
Crimping provides good mechanical connection, soldering provides a long lasting
electrical connection and forming of the heatshrink will prevent any shorting/
contact with your vehicle chassis.
Crimp here.
Crimp both wires to the butt splice using
indent type crimpers.
Solder Both Ends Here.
Solder the wires to the butt splice.
Ensure that a good connection is
made. Keep heatshrink away until after
soldering is complete and has cooled.

9
2 INSTALLATION
24V
INPUT
Optional LED
All ground points must
be connected to chassis
earth.
Start
Battery
Fuse*
Not Used
*Fuse Ratings as per table on Page 2
Red
Blue
Orange
Black
Brown
Green
12V
INPUT
OR
24V
Loads
Load
Fuse
Low Voltage
Disconnect
30A
Fuse
Auxiliary
Battery
Optional LED
All ground points must
be connected to chassis
earth.
Start
Battery
Fuse*
Not Used
to vehicle ignition
*Fuse Ratings as per table on Page 2
Red
Blue
Orange
Black
Brown
Green
12V
INPUT
Loads
Load
Fuse
Low Voltage
Disconnect
30A
Fuse
Auxiliary
Battery
Figure 2.8b - LFP2420-LV Standard setup for a 12V
Start Battery
Figure 2.8a - LFP2420 Standard setup for a 12V or 24V
Start Battery