Redarc In-Vehicle BCDC Battery Charger - Dual Input - DC to DC - 12V/24V - 40 Amp

Redarc In-Vehicle BCDC Battery Charger - Dual Input - DC to DC - 12V/24V - 40 Amp

Item # 331-BCDC1240D

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331-BCDC1240D - RV/Camper,Trailer Redarc Battery Chargers
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  • Battery Charger
  • Redarc
  • RV/Camper
  • Trailer
  • Vehicle Battery to Auxiliary Battery
  • DC to DC
  • 12V
  • Charges/Maintains
  • 200 Ah
Maintain the charge on your RV's battery with this dual-input, DC-to-DC charger. Unit installs in your vehicle and pulls power from its battery and from solar panels (not included). Great for boondocking and dry camping. Call 800-298-8924 to order Redarc battery chargers part number 331-BCDC1240D or order online at Free expert support on all Redarc products. Guaranteed Lowest Price and Fastest Shipping for Redarc In-Vehicle BCDC Battery Charger - Dual Input - DC to DC - 12V/24V - 40 Amp. Battery Chargers reviews from real customers.

  • All Info
  • Reviews (14)
  • Q & A (48)
  • Videos (2)
  • Photos
  • Why etrailer?

Redarc Battery Chargers - 331-BCDC1240D

Maintain the charge on your RV's battery with this dual-input, DC-to-DC charger. Unit installs in your vehicle and pulls power from its battery and from solar panels (not included). Great for boondocking and dry camping.


  • DC-to-DC battery charger draws power from your vehicle to provide power to an auxiliary battery on your trailer or RV
    • Ideal for larger battery banks rated 200 amp-hours and higher
  • Dual-input device can pull power from 2 sources
    • Connect yellow wire to solar panels (sold separately)
    • Connect red wire to 12V or 24V start battery
  • Multi-stage charging algorithm ensures a complete charge on secondary battery without overcharging
    • Boost stage - provides a constant charge while monitoring auxiliary battery voltage
    • Absorption stage - keeps voltage stable to avoid overcharging while bringing battery up to 100-percent charge
    • Float stage - maintains charge on auxiliary battery
  • Solar power capable - solar panels sold separately
    • Charger automatically draws power from panels before tapping into vehicle battery
    • Built-in MPPT regulator ensures most efficient power transfer possible in all conditions
  • Fully sealed construction with fan-free operation ensures durable performance under harsh conditions
    • Tested to ensure operation in temperatures as high as 176 F
    • Protects sensitive electronics from water, dust, and shock
  • Fault recognition technology prevents damage to batteries from voltage spikes, overheating, and reverse polarity connection
  • Battery isolator function prevents charger from pulling power from start battery when vehicle is off
  • Multiple mounting options for convenient installation
    • Secure the unit in the cabin of the vehicle, along a chassis frame rail, or in the engine compartment
    • Cables, fuses (331-FK60 - sold separately), and connectors sold separately
  • Made in Australia


  • Application: 12V or 24V vehicle systems with standard or smart alternators
    • Battery types supported: AGM, gel, standard led acid, calcium, and Lithium ion (LiFePO4) batteries
  • Overall dimensions: 6" long x 4-3/4" wide x 1-1/2" tall
  • Battery capacity range: 200 amp-hours and greater
  • Maximum charging voltage: 15.3V
  • Output voltage: 12V DC
  • Output power: 600 watts
  • Output current rating (continuous): 40 amps
  • Input current (maximum): 40 amps

The Redarc BCDC dual-input battery charger allows for easy charging of a DC battery while you're on the move. Most battery chargers require that you plug into an AC outlet, but this DC-to-DC charger pulls power from your vehicle's start battery instead. The BCDC also has solar power capability so that you can keep your secondary battery charged while you're parked at a remote campsite. This means that you can go off the grid without worrying about being without power.

This charger connects directly to your battery, rather than pulling power from your vehicle via the trailer connector. This is to ensure that it's able to fully charge your auxiliary battery. A standard 7-way trailer connector is limited to 10 or 15 amps of current, which will not be able to fully restore a battery for use. But this charger can transfer up to 40 amps of current to both charge and maintain your auxiliary battery.

Solar Power Compatible with MPPT Regulator

This charger can pull power from 2 different sources. The first input accepts charge from your vehicle's battery. The second input on this dual-input unit is designed to receive power from solar panels (sold separately). The built-in maximum power point tracking (MPPT) regulator on this unit ensures that the charger will get the most power possible from your panels at any given time. An MPPT regulator is able to determine the point at which your solar panels reach their maximum output. Then the regulator can simulate that load on the panels to effectively draw the most power possible. This type of regulator is more effective than traditional ones at gathering power from solar panels and at drawing power in low-light conditions.

Built-in Green Power Priority, or primary solar selection, ensures that power is pulled from your solar panels first. The BCDC will only tap into your vehicle's battery when necessary. This will save your vehicle battery from unneeded stress. It also has a built-in battery isolator function to prevent the charger from pulling power from the start battery when the vehicle is off.

3-Stage Smart Charger

REDARC BCDC Battery Charger LED Indicators

The BCDC battery charger can be used to charge AGM, gel, standard lead acid, calcium, and Lithium ion (LiFePO4) batteries. An LED on the front panel of the unit will illuminate to show the charge profile, confirming that you've wired the charger correctly based on your auxiliary battery type. This LED will be solid while the unit is charging, and it will flash when the unit is in standby mode. Additional LEDs on this panel indicate where the charger is pulling power from, and what stage of the charging process the unit is in.

This smart charger completely and efficiently charges your auxiliary battery in 3 separate stages. This ensures that the battery reaches maximum capacity without being overcharged.

The first stage of the process, the boost stage, begins when you start up your vehicle. In this mode the charger will maintain a constant current to the auxiliary battery to quickly help it regain power.

Once the unit detects that your auxiliary battery is nearing its maximum charge, the charger will move into the absorption stage. In this stage it will slowly supply the needed current to safely reach 100-percent capacity on the auxiliary battery.

The final stage is known as the float stage. In this stage the unit monitors your auxiliary battery for drops in power and supplies the needed current to keep it fully charged. If a drop in power is detected, it will revert back to the first stage and begin the charging cycle over.

Compatible with Smart Alternators

A number of newer vehicles on the market have ECU-controlled, variable-voltage alternators designed to reduce emissions and boost performance. This type of alternator varies its voltage based on the driving conditions. When the alternator voltage is low, the system can drop below 12.7V, which would deactivate a standard isolator or battery charger. However, with the Redarc BCDC battery charger, this is not an issue. Simply connect the blue override wire to the vehicle ignition and the charger will recognize that the car battery is still receiving a charge from the alternator, even if the voltage has dropped. The charger will modify its voltage requirements so that it can continue to pull power until the start battery drops to 12V, as opposed to the standard 13.2V.

Versatile Mounting

This unit can be mounted in a variety of places to best suit your application. Use the 4 mounting tabs to secure the unit in the cabin of your vehicle, along a chassis frame rail, or in the engine compartment. The charger should be mounted as close as possible to the auxiliary battery being charged to prevent current loss. The farther the current has to travel, the more amperage is lost. A larger diameter wire will allow more current to flow through it, which can offset the current loss that occurs with longer lengths of wire. As a result, it is recommended that you use a heavier gauge wire to cover longer distances. The table below outlines the recommended wire size for a given length of cable:

Redarc BCDC Dual Battery Charger Wiring Guide

To ensure a low-resistance connection, you will want to use MIDI fuses (331-FK60 - sold separately) when connecting the BCDC to your batteries.

For a typical lead acid battery setup, refer to the wiring diagram (shown with fuses and optional LED and solar panel - sold separately) below:

Redarc BCDC Dual Battery Charger Standard Lead Battery Wiring Diagram

For a typical Lithium ion (LiFePO4) battery setup, refer to the wiring diagram (shown with fuses and optional LED and solar panel - sold separately) below:

Redarc BCDC Dual Battery Charger Lithium Battery Wiring Diagram

BCDC1240D REDARC In-Vehicle BCDC Battery Charger - Dual Input - DC to DC - 12V/24V - 40 Amp

331-BCDC1240D Installation InstructionsInstallation Details 331-BCDC1240D Installation instructions

Video of Redarc In-Vehicle BCDC Battery Charger - Dual Input - DC to DC - 12V/24V - 40 Amp

Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.

Video Transcript for Redarc Battery Chargers - Battery Charger - 331-BCDC1240D Review

Speaker 1: Today we're going to take a look at the Redarc 40 amp dual input multi stage, 12 volt to 24 volt, DC to DC in-vehicle battery charger. This DC to DC battery charger will draw power from your vehicle, provides power to an auxiliary battery on your trailer or RV. It's ideal for battery bank traded 200 amp powers and higher. It does uses a multi-stage charging algorithm, to ensure a complete charge or your secondary battery, without over charging. It has a boost stage, which provides a constant charge, while monitoring auxiliary battery voltage, and it has an absorption stage, which keeps your voltage stable to avoid overcharging, while bringing the battery up to 100% charge. Finally, has a float state, which maintains your charge on your auxiliary battery.It is a dual input device.

It can pull power from two sources. Can use the red wire and connect it to 12 volt or 24 volt start battery. Use the yellow wire and connect it to solar panels. Now, the solar panels we do sell separately on our website. Since this is solar power capable, the charge will automatically draw power from the panels before tapping into your vehicle battery.

It does use a built-in MPPT regulator, to ensure most efficient power transfer possible in all conditions.This is a fully sealed construction. It's a fan free operation, to ensure durable performance under harsh conditions. It is tested to endure operation in temperatures as high as 176 degrees fahrenheit, and this will protect your sensitive electronics from water, dust and shock. Does use fault recognition technology, prevents damage to your batteries from voltage spike, overheating and reverse polarity connection.The battery isolator function prevents the charger from pulling power from your start battery when the vehicle is off. Does have multiple mounting options for convenient installation.

You can secure this unit in the cab of your vehicle, along a chassis frame rail, or even in the engine compartment.The cables, fuses and connectors, we do separately on our website. To install this, it's Part Number 331-FK60. This part is made in Australia. Few specs again, the application is for 12 volt or 24 volt vehicle systems, with standard or smart alternators. The battery types supported are AGM, gel, standard lead acid, calcium and lithium ion.

Battery capacity range, 200 amp hours and greater. Maximum charging voltage is 1523 volts. Output voltage, 12 volts DC. Output power is 600 watts. Output current rating continuous is 40 amps and input current max is 40 amps. Comes with a nice, detailed instruction manual in how it operates and how to install it.The last thing I want to give you the overall dimensions on it. It's a very small unit. Overall length, 6'-1/2". Overall width, including the mounting brackets is going to be right at 4-3/4", and overall height is 1-1/2" tall. That should do it for the review on the Redarc 40 amp dual input multi stage, 12 volt or 24 volt DC to DC in-vehicle battery charger.

Customer Reviews

Redarc In-Vehicle BCDC Battery Charger - Dual Input - DC to DC - 12V/24V - 40 Amp - 331-BCDC1240D

Average Customer Rating:  4.9 out of 5 stars   (14 Customer Reviews)

Maintain the charge on your RV's battery with this dual-input, DC-to-DC charger. Unit installs in your vehicle and pulls power from its battery and from solar panels (not included). Great for boondocking and dry camping.

- 331-BCDC1240D

One year later: Installed this to charge 2 - 100Ah Lithium Batteries from 160 Amp Alternator - It does a much better job than just the alternator itself - the boost speeds up charging by a x4 factor - worth every penny. Highly recommend - easy install with clear instructions. 602885

- 331-BCDC1240D

I installed a BCDC1240D (with optional fuse kit) in my Winnebago Revel (Mercedes Sprinter). The instructions are clear and I was able to figure out the wiring requirements pretty easily. I wired the Redarc with a switch to change between profile C (winter) and B (summer). The batteries are mounted below the vehicle so I probably need profile B at higher temperatures in the summer. I have included a picture of the Redarc installed in the passenger's seat pedestal in the van. Most of the wiring in there is Mercedes and Winnebago. You should be able to identify the Redarc (bottom center), and the two fuse holders (fuses not yet install) near the blue tape. 583167

- 331-BCDC1240D

Is working great in my Silverado to keep auxiliary battery charged for the bed accessories. Just added a solar suitcase to it for charging and using electrical without engine. Thinking about installing the jump circuit just for safety 646758

- 331-BCDC1240D

Install took a little time. You will need a hydraulic connector press and then you will have to solder connectors. I ordered connectors off of the internet 637835

- 331-BCDC1240D

Excellent product, easy install. If you want the option to charge and maintain an Auxiliary Battery from main battery or solar, this is an excellent compact unit. Installed this unit a year ago for a Four wheel camper. Maintain a charge on the road and camping off road, still working strong, no longer need to charge battery in the off season using solar switching, awesome for camping and maintain healthy battery. Thanks to etrailer for offering Redarc products, ease online ordering, support and on time delivery, outstanding. Highly recommend doing business with etrailer and buying this product and the Bulldog connectors! 628464

- 331-BCDC1240D

I have 300ah Lifepo4 batteries from Renogy.. 300 watt solar.. this unit will charge via solar or vehicle.. one or the other .. whichever has more power.. I see the lights on and see it working.. the reason I like this unit is because my batteries are only being charged from one charging source. This is safer and will improve battery life. I just wish it could have a battery and voltage meter.. I guess I need to buy a battery monitor.. This is almost the perfect device.. it needs a display for battery life and voltage.. I would love to know what it is doing. 586562

- 331-BCDC1225D

Review from a similar Redarc BCDC in Battery Chargers

Too easy. Does what it is deaigned to do. Had to modify a Law Enforcement Vehicle with limited space. Voltage and charge test Alesha’s proved “solid”. 594415

- 331-BCDC1225D

Review from a similar Redarc BCDC in Battery Chargers

Easy to install. Instructions that come with all Redarc products are straightforward. It's working great so far charging a 105 Ah battery that is running a fridge/freezer, some lights, and assorted other gadgets. 508790

- 331-BCDC1225D

Review from a similar Redarc BCDC in Battery Chargers

I have used this in my custom camper for one year. It is connected to a Size D gel cell enology battery that drives an inverter to power fridge, micorwave, tv and lights. I have never had an issue with vehicle battery or the gel cell even when used overnight. Works as advertised. 634086

- 331-BCDC1225D

Review from a similar Redarc BCDC in Battery Chargers

Product has worked as stated. 5 stars! 629151

- 331-BCDC1225D

Review from a similar Redarc BCDC in Battery Chargers

Works as advertised. It bumps the charging voltage from my Tacoma up to where I can get 20 amps charging current into the trailer battery even while the engine idles. The unit makes up for the voltage drop through the trailer 7 pin connector and about 35 feet of wire plus the ground circuit.. The integrated solar controller works as well as the separate controller the REDARC replaced. Installation could be easier, the REDARC unit has large wire pigtails that must be butt spliced. It would be easier if the unit used a clamp style terminal block. 601615

- 331-BCDC1225D

Review from a similar Redarc BCDC in Battery Chargers

I recieved the Redarc bcdc 1225d charger today. This will not be installed for awhile but after looking the unit over, seems to be of high quality. Small but somewhat heavy for the size l would think very good internal components. I chose this over others due to what appears as a better water proof unit. Also the wiring is heavier. Im hoping this unit will last yrs in my setup. I gave 4 stars due to non install yet and packaging. 590921

- 331-BCDC1225D

Review from a similar Redarc BCDC in Battery Chargers

I ordered the BCDC1225 on Friday and received it on Monday, before noon ... how great is that! Everything appears to be in order. I'm looking forward to getting this charger hooked up to run the fans in the trailer that I carry my dogs in (it's a specially designed trailer which remains cool, but moving air keeps them even more comfortable). Notably, the help that I've received even BEFORE ORDERING has been outstanding. I will turn to for all future trailer-related needs. (Once installed, I'll post a performance review.) 565968

- 331-BCDC1225D

Review from a similar Redarc BCDC in Battery Chargers

Quick shipping, Haven’t hooked it up ye t. 469810


Ask the Experts about this Redarc Battery Chargers
Do you have a question about this Battery Charger?

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Info for this part was:

Edited by:
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Installed by:
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Expert Research:
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Video Edited:
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Expert Research:
Adam R
Video by:
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Updated by:
Sarah W
Written by:
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