DOMETIC MT LB 40 DC Charger Instruction Manual

DOMETIC MT LB 40 DC Charger

Product Usage Instructions

• Read all instructions carefully before use to ensure the safe and proper operation of the charger.
• Familiarize yourself with the symbols used in the manual to understand warnings, cautions, and important information.
• Follow all safety instructions provided to prevent accidents or damage to the charger or connected devices.
• Check the package contents against the list provided to ensure all components are included.
• Understand the intended purpose of the charger and only use it as described in the manual.
• Identify the appropriate users for the charger based on skill level and knowledge of electrical equipment.
• Learn about the technical specifications and features of the charger to utilize it effectively.
• Follow the installation instructions carefully to set up the charger correctly and securely.
• Adjust the settings of the charger as needed based on your specific requirements and power input/output.
• Start using the charger by following the operational guidelines provided in the manual for efficient charging.
• Maintain the charger by cleaning it regularly with a dry cloth to ensure longevity and proper functioning.
• If you encounter any issues with the charger, refer to the troubleshooting section for guidance on resolving common problems.

FAQ

• Q: What should I do if the charger is not powering on?
• A: Check the power source, and connections, and ensure that all settings are correct as per the manual.
• Q: Can I use the charger with both 12V and 24V batteries?
• A: Yes, the charger is compatible with both 12V and 24V batteries with appropriate output settings.
• Q: How do I know when the battery is fully charged?
• A: The charger may indicate a full charge through LED lights or a display screen depending on the model.

Copyright
© 2024 Dometic Group. The visual appearance of the contents of this manual is protected by copyright and design law. The underlying technical design and the products contained herein may be protected by design, patent or pending patent. The trademarks mentioned in this manual belong to Dometic Sweden AB. All rights are reserved.

Important notes
Please read these instructions carefully and follow all instructions, guidelines, and warnings included in this product manual to ensure that you install, use, and maintain the product properly at all times. These instructions MUST stay with this product.
By using the product, you hereby confirm that you have read all instructions, guidelines, and warnings carefully and that you understand and agree to abide by the terms and conditions as set forth herein. You agree to use this product only for the intended purpose and application and by the instructions, guidelines, and warnings as outlined in this product manual as well as by all applicable laws and regulations. A failure to read and follow the instructions and warnings set forth herein may result in an injury to yourself and others, damage to your product or damage to other property in the vicinity. This product manual, including the instructions, guidelines, warnings, and related documentation, may be subject to changes and updates. For up-to-date product information, please visit documents.dometic.com.

Explanation of symbols

DANGER!

• Indicates a hazardous situation that, if not avoided, will result in death or serious injury.

WARNING!

• Indicates a hazardous situation that, if not avoided, could result in death or serious injury.

CAUTION!

• Indicates a hazardous situation that, if not avoided, could result in minor or moderate injury.

NOTICE!

• Indicates a situation that, if not avoided, can result in property damage.

General safety instructions

Also observe the safety instructions and stipulations issued by the vehicle manufacturer and authorized workshops.

WARNING! Electrocution hazard

• Installation and removal of the device may only be carried out by qualified personnel.
• Do not operate the device if it is visibly damaged.
• If this device’s power cable is damaged, the power cable must be replaced to prevent safety hazards.
• This device may only be repaired by qualified personnel. Improper repairs can lead to considerable hazards.
• If you disassemble the device: Detach all connections. Ensure that no voltage is present on any of the inputs and outputs.
• Do not use the device in wet conditions or submerge in any liquid. Store in a dry place.
• Only use accessories that are recommended by the manufacturer.
• Do not modify or adapt any of the components in any way.
• Disconnect the device from the power supply:
• Before each cleaning and maintenance
• After use
• Before changing a fuse
• Before carrying out electrical welding work or work on the electrical system

WARNING! Health hazard

• This device can be used by children aged 8 years and above and persons with reduced physical, sensory, or mental capabilities or lack of experience and knowledge if they have been given supervision or instruction concerning use of the device in a safe way and understand the hazards involved.
• Electrical devices are not toys. Always keep and use the device out of the reach of very young children.
• Children must be supervised to ensure that they do not play with the device.
• Cleaning and user maintenance shall not be done by children without supervision.

NOTICE! Damage hazard

• Before start-up, check that the voltage specification on the data plate is the same as that of the power supply.
• Ensure that other objects cannot cause a short circuit at the contacts of the device.
• Ensure that the negative and positive poles never come into contact.

Installing the device safely

DANGER! Explosion hazard
Never mount the device in areas where there is a risk of gas or dust explosion.

WARNING! Risk of injury

• Ensure that the device is standing firmly. The device must be set up and fastened in such a way that it cannot tip over or fall.
• When positioning the device, ensure that all cables are suitably secured to avoid any form of trip hazard.

NOTICE! Damage hazard

• Do not place the device near heat sources (heaters, direct sunlight, gas ovens, etc.).
• Place the device in a dry location where it is protected against splashing water.

Operating the device safely

WARNING! Explosion hazard

• Only use the device in closed, well-ventilated rooms.
• Do not operate the device under the following conditions:
• In salty, wet or damp environments
• In the vicinity of corrosive fumes
• In the vicinity of combustible materials
• In areas where there is a danger of explosions

WARNING! Electrocution hazard

• Observe that parts of the device may still conduct voltage even if the fuse has blown.
• Do not disconnect any cables when the device is still in use.

NOTICE! Damage hazard

• Ensure that the air inlets and outlets of the device are not covered.
• Ensure good ventilation.
• The device shall not be exposed to rain.

Safety precautions when handling batteries

WARNING! Risk of injury

• Batteries contain aggressive and caustic acids. Avoid battery fluid coming into contact with your body. If your skin does come into contact with battery fluid, wash that part of your body thoroughly with water. If you sustain any injuries from acids, contact a doctor immediately.
• When working on batteries, do not wear any metal objects such as watches or rings. Lead acid batteries can cause short circuits which can cause serious injuries.
• Only use insulated tools.
• Do not place any metal parts on the battery.
• Wear goggles and protective clothing when working on batteries. Do not touch your eyes when working on batteries.
• Do not use defective batteries.

WARNING! Health hazard
Keep the battery out of the reach of children.
CAUTION! Electrocution hazard

• Keep the battery away from water.
• Avoid short circuits.
• Avoid clothing rubbing against the battery.
• Wear antistatic clothing when handling the battery.

CAUTION! Explosion hazard

• Do not place the battery in an area with flammable liquids or gases.
• Never attempt to charge a frozen or defective battery. Place the battery in a frost-free area and wait until the battery has acclimatized to the ambient temperature. Then start the charging process.
• Do not smoke, use an open flame, or cause sparking near the engine or a battery.
• Keep the battery away from heat sources.

NOTICE! Damage hazard

• Only use rechargeable batteries.
• Prevent any metal parts from falling on the battery. This can cause sparks or short-circuit the battery and other electrical parts.
• Ensure that the polarity is correct when connecting the battery.
• Follow the instructions of the battery manufacturer and those of the manufacturer of the system or vehicle in which the battery is used.
• If the battery has to be removed, first disconnect the ground connection. Disconnect all connections and all consumers from the battery before removing it.
• Only store fully charged batteries. Recharge stored batteries regularly.
• Do not carry the battery by its terminals.

Safety precautions when handling lithium batteries

CAUTION! Risk of injury
Only use batteries with an integrated battery management system and cell balancing.
NOTICE! Damage hazard

• Only install the battery in environments with an ambient temperature of at least 0 °C.
• Avoid deep discharge of the batteries.

Safety precautions when handling lead acid batteries

CAUTION! Health hazard
The water-acid liquid inside the battery can evaporate and cause an acidic odor. Use the battery only in a well-ventilated area.

NOTICE! Damage hazard

• The battery is not sealed. Do not turn the battery on its side or upside down. Place the battery on a horizontal surface.
• Check the acid level for open lead acid batteries regularly.
• Immediately recharge deeply discharged lead acid batteries to avoid sulfation.

Scope of delivery

• DC-DC Charger
• Fuse, 80 A
• Fuse, 110 A
• Battery temperature sensor

Intended use
The battery charger is intended to monitor and charge house batteries in recreational vehicles by the alternator while driving.
The charger is intended to charge the following battery types:

• Lead acid batteries
• Lead gel batteries
• Absorbed glass mat (AGM) batteries
• LiFePO4 batteries

The battery charger is not intended to charge other types of batteries (e. g. NiCd, NiMH, etc.). The charger is suitable for:

• Installation in recreational vehicles
• Stationary or mobile use
• Indoor use

The charger is not suitable for:

• Mains operation
• Outdoor use

This product is only suitable for the intended purpose and application by these instructions.
This manual provides information that is necessary for the proper installation and/or operation of the product. Poor installation and/or improper operation or maintenance will result in unsatisfactory performance and a possible failure.
The manufacturer accepts no liability for any injury or damage to the product resulting from:

• Incorrect installation, assembly or connection, including excess voltage
• Incorrect maintenance or use of spare parts other than the original spare parts provided by the manufacturer
• Alterations to the product without express permission from the manufacturer
• Use for purposes other than those described in this manual

Dometic reserves the right to change product appearance and product specifications.

Target Group

The electrical power supply must be connected by a qualified electrician who has demonstrated skill and knowledge related to the construction and operation of electrical equipment and installations, and who is familiar with the applicable regulations of the country in which the equipment is to be installed and/or used, and has received safety training to identify and avoid the hazards involved.

Technical Description

General description
The charger charges the house battery by the alternator with the following charging current while driving:

• MT LB 40: 40 A
• MT LB 80: 80 A
• MT LB 24-40: 40 A
• MT LB 24-60: 60 A
• MT LB 12/24-20: 20 A
• MT LB 12/24-40: 40 A
• MT LB 24/12-40: 40 A
• MT LB 24/12-80: 80 A

The charger can be adapted to different battery types via DIP switches. The charger offers the following functions:

• Microprocessor-controlled, temperature-compensated IU0U charging programs for various battery types
• Buffer operation: Compliance with the charging characteristics even when the battery is charged with consumers connected
• On-board mains suppression filter: Ensures parallel operation of the charger with other charging sources, for example, mains supply chargers, solar systems, or generators
• Automatic compensation of voltage loss caused by the charging cable length (house battery)
• AUX connection usable for controller output, split-charge relay, or electrical devices (only MT LB 40, MT-LB 80, MT-LB 24-40, MT-LB 24-60)

The charger has the following protective mechanisms:

• High voltage protection
• Low voltage protection
• High-temperature protection
• Low-temperature protection (only LiFePO4 batteries)
• Battery overcharge protection (only with temperature sensors)
• Reverse current protection
• Protection against short circuit
• Reverse polarity protection (only for house battery connection)

The charger can be connected to the TD283 display (optional) for remote control. If a Bluetooth N-BUS device is present in the N-BUS network, the mobile app can be used for controlling the charger.
A temperature sensor can be connected to monitor the battery temperature during the charging process.

Description of the device
Fig. 1
Table 1: Connections and controls

Table 2: Status LED

Voltage higher than 12 V or 24 V (depending on the model).

Orange flashing| Battery charging.

Output voltage lower than 12 V or 24 V (depending on the model).

Green| Battery completely charged, float mode.
Red flashing| An error occurred (see Troubleshooting)

Fig. 2 Table 3: Terminal block

(terminal 15)
2| Sense +| Signal (+) output voltage
3| Sense –| Signal (-) output voltage
PIN| Designation| Description
---|---|---
4| Temp 1| Connection for temperature sensor (optional)
5| Temp 2
6| –| Not used
7| –| Remote charging status signal

Battery charging function
A main charging cycle of the house battery is initiated in the following situations:

• After a standstill of the alternator
• After falling below the reset voltage Fig. 3

In all charging phases, almost the entire possible charger current is available for the additional supply of DC loads without discharging the battery.
The charging characteristics for fully automated continuous operation without monitoring are referred to as IU0U characteristics.
Analysis phase (Recondition and pulse)
The battery is deeply discharged (> 10 %). The battery charge is analyzed with increasing charging current.
I phase (Constant current phase – Bulk)
At the beginning of the charging process, the empty battery is constantly charged with half of the maximum charging current (50 %). The charging current increases to 100 % after 1 minute. Deeply discharged lead batteries are charged with reduced charging current until the battery voltage exceeds 12 V. The duration of the I phase depends on the state of the battery, the load from the consumers, and the state of charge. For safety reasons, the I phase is terminated after a maximum of 15 h (in case of battery cell defects or similar).
U1 phase (Constant voltage phase – Absorption)
The U1 phase starts when the battery is fully loaded. The charging current is reduced. During the U1 phase, the battery voltage is kept constant at a high level. The duration of the U1 phase depends on the battery type and the depth of discharge.
Desulfation phase
A constant current will be delivered, allowing the battery voltage to rise independently to the maximum value. The desulfation phase is not used for LiFePO4 batteries.
U2 phase (Trickle charging – Float)
The U2 phase serves to maintain the battery capacity (100 %). The U2 phase runs at lowered charging voltage and variable current. If DC loads are connected, they are powered by the device. Only if the power required exceeds the capacity of the device, this surplus power is provided by the battery. The battery then is discharged until the device re-enters the I phase and charges the battery. The U2 phase is limited to between 24 and 48 h depending on the battery type.

Installation

Before installation
Observe the following instructions when selecting an installation location:

• Ensure that the mounting surface is solid and level.
• Choose a well-ventilated installation location to avoid overheating.
• Observe a distance of 10 cm to the ventilation openings of the cooling fan. Choose a suitable installation location to connect the power cables to the battery.

Mounting the charger

NOTICE! Damage hazard
Before drilling any holes, ensure that no electrical cables or other parts of the vehicle can be damaged by drilling, sawing and filing.

1. Ensure that the vehicle’s engine and the battery chargers are switched off.
2. Set the switch to the OFF position.
3. Screw the charger to the mounting surface.

Fig. 4

Determining the cable cross-section
The cable cross-section of the power cables depends on the model and on the cable length.
Table 4: Cable cross-section

Select power cables of the suitable cross-section.

Connecting the battery charger

WARNING! Electrocution hazard

• Observe the recommended cable cross-sections, cable lengths, and fuse.
• Only MT LB 40, MT-LB 80, MT-LB 24-40, and MT-LB 24-60: Connect an external 60 A fuse to the AUX connection.
• Only MT LB 12/24-20 and MT-LB 12/24-40: Do not insert an external fuse to the AUX connection.
• The input and output voltage must not exceed 35 V.

CAUTION! Fire hazard
Place the fuses near the batteries to protect the charger from short circuits and possible burning.

NOTICE! Damage hazard Do not reverse the polarity.

Observe the following instructions when connecting the charger:

• Select the appropriate connection variant, Connection variant A, Connection variant B, Connection variant C, Connection variant D, Connection variant E.
• Use suitable measuring instruments:
• Multimeter with DC voltage measurement, 200 V or autoscale
• Amperometric clamp with direct measurement (100 A scale or higher)
• Always connect the charger before connecting the batteries.
• Do not use ferrules. Strip the cable ends as follows:
• Signal cable 12 mm (0.5 mm² … 1.5 mm²)
• Charging cable 15 mm

Fig. 5

Table 5: General connection diagram

1. Connect the negative pole of the starting battery to GND.
2. Connect the fuse holder to the positive pole of the starting battery.
3. Connect the other end of the fuse holder to INPUT.
4. Insert a fuse into the fuse holder.
5. Connect the fuse holder to the positive pole of the house battery.
6. Connect the other end of the fuse holder to OUT.
7. Insert the output fuse into the fuse holder.
8. Connect the D+ or ignition+ signal wire to PIN 1 of the terminal block.
9. Optional: Connect the output voltage control positive signal cable (+SENSE) from PIN 2 of the terminal block to the positive pole of the house battery, and the negative signal cable (-SENSE) from PIN 3 of the terminal block to the negative pole of the house, using a cable with 1 mm² cross-section. This connection will reduce the voltage drop on power cables during the charging process by an electronic control device.
10. Optional, only applicable to models MT LB 40, MT-LB 80, MT-LB 24-40, MT-LB 24-60: Connect a device to the AUX connection, see connection diagram, Connection variant B, Connection variant C, Connection variant D, Connection variant E.

Connection variant A
Connection variant for basic installation with 12 V or 24 V batteries.

To connect the battery charger proceed as shown.

Fig. 6

Table 6: Connection diagram variant A

Connection variant B
Connection variant for vehicles without control unit or with a split charge relay.

To connect the battery charger proceed as shown.

Fig. 7

Table 7: Connection diagram variant B

Connection variant C
Connection variant for vehicles with control unit already installed.

To connect the battery charger proceed as shown.

Fig. 8

Table 8: Connection diagram variant C

Connection variant D
Connection variant for a 24 V system for vehicles without control unit or with a split charge relay.

To connect the battery charger proceed as shown.

Fig. 9

Table 9: Connection diagram variant D

Connection variant E
Connection variant for a 24 V system for vehicles with control unit already installed.

To connect the battery charger proceed as shown.

Fig. 10

Table 10: Connection diagram variant E

Configuration

NOTICE! Damage hazard
Use a small screwdriver to carefully move the DIP switches to the required position.

Setting up the alternator type
This function can only be activated by the DIP switch, not by an external controller (optional TD283 display or mobile app).

Slide the DIP switch according to your vehicle alternator type.

Table 11: Alternator configuration

Setting the charging program

NOTICE! Damage hazard
Only use batteries that are suitable for the specified charging voltage.

Select the charging program suitable or the type of house battery used based on the battery manufacturer’s specifications, the information on the charging curves (see Battery charging function) and the technical data (see Technical data ). The specified charging times apply to an average ambient temperature of 20 °C. The setting charging program can be activated by the DIP switch on the charger or, if a Bluetooth N-BUS device is present in the N-BUS network, via the TD283 display or via the mobile app.

Slide the DIP switches to the position shown in the table below to set the charging program for the respective type of house battery.
Table 12: Charging curve configuration

Setting the silent mode (optional)
The silent mode can be used in order to not to be disturbed by the cooling fan or alarms. By activating this mode the maximum charging current may be reduced to secure its integrity. Silent mode can be activated by the DIP switch on the charger or, if a Bluetooth N-BUS device is present in the N-BUS network, via the display or via mobileapp .

Slide the DIP switch according to the desired mode.

Table 13: Silent mode configuration

Setting up the input current limit
This setting limits the input current to the charger. It can be useful when the power source (e.g. alternator) is not so powerful. This setting can be activated in order not to stress the system. This function can only be activated by the DIP switch, not by a external controller (display or app).

Slide the DIP switch accordingly.

Table 14: Input current limit configuration

Setting up the output current limit
For each model you can choose between three output currents. This setting can be useful in case the maximum out-put current exceeds the recommended values for charging bord batteries, as might happen with AGM or Lead/Acid batteries in general.
This function can only be activated by the DIP switch, not by an external controller (optional TD283 display or mobile app).

Slide the DIP switches accordingly.
Table 15: Output current limit configuration

Operation

Performing the system operation check
The state of charge (SoC) of the house battery must be at 75 % of the capacity.

1. Turn off the engine.

2. Use a voltmeter to check the voltage of the house battery .

3. Check if the DIP switch settings for the battery requirements and for the alternator type (traditional or smart) are correct.

4. Turn the switch to position ON.

5. Turn on the engine.
   The LED lights up red or orange to indicate that the charging of the battery is in progress.

6. Check the voltage of the house battery with the voltmeter and compare it to the previous measurement.
   The voltage must be higher than before.

7. After 2 min verify the maximum current data with a clamp meter.
   This phase lasts a few seconds if the house battery is completely charged.

8. Check the voltage of the starting battery at the battery poles with a voltmeter and compare it with the voltage between the charger’s positive terminal and negative terminal.

The difference between the two connections may be max. 0.7 V. If the voltage difference is higher than 0.7 V, use a power cable with a larger cross-section for the connection to positive pole of starting battery (INPUT) or improve the ground connection (GND).

Cleaning
The device is maintenance-free. Occasionally clean the product with a damp cloth.

Troubleshooting

insulation faults, breaks or loose connec- tions.

If you cannot find an error, con- tact an authorized service agent.

Short circuit has been generated.| The device fuse must be re- placed by an authorized service agent after it has been triggered by excess current.
The LED flashes red and a beep sounds.| The device fuse is defective.| The device fuse must be re- placed by an authorized service agent after it has been triggered by excess current.

Disposal

• Recycling packaging material: Place the packaging material in the appropriate recycling waste bins wher-ever possible.

Recycling products with non-replaceable batteries, rechargeable batteries, or light sources:

• If the product contains any non-replaceable batteries, rechargeable batteries, or light sources, you don’t have to remove them before disposal.
• If you wish to finally dispose of the product, ask your local recycling center or specialist dealer for details about how to do this in accordance with the applicable disposal regulations.
• The product can be disposed free of charge.

Warranty

The statutory warranty period applies. If the product is defective, please contact the manufacturer’s branch in your country (see dometic.com/dealer) or your retailer.
For repair and warranty processing, please include the following documents when you send in the device:

• A copy of the receipt with purchasing date
• A reason for the claim or description of the fault

Note that self-repair or nonprofessional repair can have safety consequences and might void the warranty.

Technical data

 | MT LB 40, MT LB 80| MT LB 24-40,

MT LB 24-60

| MT LB 12/24-20, MT LB 12/24-40| MT LB 24/12-40, MT LB 24/12-80
---|---|---|---|---
Input voltage| 9 V … 16| 18 V … 32| 9 V … 16| 18 V … 32
Output voltage| 9 V … 16| 18 V … 32| 18 V … 32| 9 V … 16
Max. input voltage| 35 V
Output charging current| 40 A| 80 A| 40 A| 60 A| 20 A| 40 A| 40 A| 80 A
Max. standby current consumption| ≤ 4 mA
Peak efficiency| 97 %
Ambient temperature for operation| -20 °C … 60 °C
Ambient humidity| ≤ 95 %, non-condensing
Protection type| IP21
Dimensions| 210 mm × 191 mm × 75 mm
Weight| 1080 g
Certification| 10R-06/01 3831 00

CONTACT

• A complete list of Dometic companies, which comprise the Dometic Group, can be found in the public filings o
• DOMETIC GROUP AB
• Hemvärnsgatan 15
• SE-17154 Solna
• Sweden
• dometic.com/dealer
• dometic.com/contact
• dometic.com/sales-offices
• dometic.com

References

• Find a Dealer | Dometic USA

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