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Redarc In-Vehicle BCDC Battery Charger - Dual Input - DC to DC - 12V/24V - 25 Amp
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Redarc In-Vehicle BCDC Battery Charger - Dual Input - DC to DC - 12V/24V - 25 Amp

Item # 331-BCDC1225D
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Redarc In-Vehicle BCDC Battery Charger - Dual Input - DC to DC - 12V/24V - 25 Amp RV/Camper,Trailer 331-BCDC1225D
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Maintain the charge on your RV's battery with this dual-input, DC-to-DC smart charger. Unit installs in your vehicle or trailer and pulls power from your solar panels before tapping into the vehicle battery. Great for boondocking and dry camping. Call 800-298-8924 to order Redarc battery charger part number 331-BCDC1225D or order online at etrailer.com. 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 - 25 Amp. Battery Charger reviews from real customers.
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Redarc Battery Charger - 331-BCDC1225D

  • RV/Camper
  • Trailer
  • Battery Charger
  • Redarc
  • 12V
  • Solar Panels to Auxiliary Battery
  • Vehicle Battery to Auxiliary Battery
  • Charges/Maintains
  • 75 Ah
  • 200 Ah

Maintain the charge on your RV's battery with this dual-input, DC-to-DC smart charger. Unit installs in your vehicle or trailer and pulls power from your solar panels before tapping into the vehicle battery. 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 battery banks rated between 75 and 200 amp-hours
  • 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, in the engine compartment, or on your trailer
    • Cables, fuses (331-FK40 - 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 lead acid, calcium, and Lithium ion (LiFePO4) batteries
  • Overall dimensions: 4-3/4" long x 4" wide x 1-1/2" tall
  • Battery capacity range: 75 amp-hours - 200 amp-hours
  • Maximum charging voltage: 15.3V
  • Output voltage: 12V DC
  • Output power: 375 watts
  • Output current rating (continuous): 25 amps
  • Input current (maximum): 25 amps
  • 2-Year warranty

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 25 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, in the engine compartment, or on your trailer. 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-FK40 - 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

BCDC1225D REDARC In-Vehicle BCDC Battery Charger - Dual Input - DC to DC - 12V/24V - 25 Amp

Installation Details 331-BCDC1225D Installation instructions

California residents: click here

Customer Reviews

Redarc In-Vehicle BCDC Battery Charger - Dual Input - DC to DC - 12V/24V - 25 Amp - 331-BCDC1225D

Average Customer Rating:  4.9 out of 5 stars   (35 Customer Reviews)

Maintain the charge on your RV's battery with this dual-input, DC-to-DC smart charger. Unit installs in your vehicle or trailer and pulls power from your solar panels before tapping into the vehicle battery. Great for boondocking and dry camping.

- 331-BCDC1225D

Thanks etrailer for bringing this product to the USA market. I found the REDARC chargt talked about on Australian “caravan” blogs before etrailer had it for sale and considered trying to buy it from an Australian vendor. I use the BCDC1225D to charge my 200 amp hour lithium battery in my truck camper. I have 350 watts of rooftop solar and ran 8gauge wiring from the truck battery through a bed mounted Andersen connector. The very compact size of the unit allowed me to tuck it away in a small space in my camper. I wired it up just as suggested in the instructions and it worked perfectly. I’m getting the full 25 amp charge that the solar panels will provide at midday and get the added benefit of being able to charge at the same rate while driving in the dark. The thing works great. Thanks again etrailer for bringing this product to the USA market 677741

I’m still loving my Redarc. Five Stars!
Chris J - 08/01/2020


- 331-BCDC1225D

This thing is amazing and is the solution for anyone who wants to charge a battery more than a few feet from the alternator. I have a truck with a bed mounted battery which is about 22 feet of wiring from the main battery and it charges perfectly. My Dometic fridge in the bed has been running non stop for a year with one small solar panel a marine battery and this charger connected to the alternator and solar 905811

- 331-BCDC1225D

Fantastic product.! I mounted it on the outside of my power supply box connected to the auxiliary battery on my camp trailer. It’s seen sun, rain, snow, mud and dirt, keeps my battery charged and handles all the switching between solar panel and alternator charging. Made in Australia which is the next best thing to made in the USA. 831602

- 331-BCDC1225D

I haven't installed yet, but have heard good things about the product. I have a 4x4 that sits at the airport for 6 months, currently being charged by a 170 w solar panel, feeding both battery's, so the redark will provide charging to the second battery when the car is run. With fridge load, solar not enough. 822021

- 331-BCDC1225D

Good quality. Is holding up after a year of use. My trailer stays in the garage most of the time, so this only gets used when I am out camping or leaving it in the drive way on occasion. 822037

- 331-BCDC1225D

works as claimed, instructions were great. No issues at all. 816861

- 331-BCDC1225D

"Great piece of kit!" Seriously well worth the beans. The REDARC allows me to charge my trailer battery while towing. The trailer's converter supplies 13.6 VDC, which is not sufficient to charge my on board battery. The REDARC brings this DC voltage up to approximately 14.7 VDC. So my Truck charging system provides the trailer battery while travelling, and the on board trailer converter,(while AC CONNECTED at the site), sends DC voltage to the REDARC via the Solar Panel Input side of the unit, as I do not have a solar panel. I called Australian support number, and asked if this was an acceptable means of connection. They were most helpful and knowledgeable. 791155

- 331-BCDC1225D

The product works great - I currently use it in the back of my truck to charge a 100 AH LI battery. My next step is to use the solar charging feature and see how it works swapping back and forth between truck / solar recharge. 786960

- 331-BCDC1225D

Great product and works to perfection. Thanks etrailer. 779626

- 331-BCDC1225D

veryy satisfied with product and customer service. 763696

- 331-BCDC1225D

Work great. Charges from the trailer plug and a 100 watt solar panel on the roof. Never have to charge the winch battery. No worries all winter when the trailer just sits. Would buy again. 739139

Works great. Don’t have to worry about the trailer battery freezing during the winter.
Bob H - 01/19/2021


- 331-BCDC1225D

Used for full time suv living and traveling. Kept my lithium battery and fridge up and running with solar as well. Awesome product. 727905

- 331-BCDC1225D

Great product. 686891

Works great. Used for running fridge on auxiliary battery.
Kenneth - 08/14/2020


- 331-BCDC1225D

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

Product has worked as stated. 5 stars! 629151

- 331-BCDC1225D

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

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

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

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 etrailer.com for all future trailer-related needs. (Once installed, I'll post a performance review.) 565968

- 331-BCDC1225D

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

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

- 331-BCDC1240D

Review from a similar BCDC in Battery Charger

Brilliant product! Charges trailer battery while you drive! When full-timing (almost always dry camping) we frequently found it necessary to run the generator *after* arriving at a new campsite because the “charge” line on the 7 blade RV connector delivered so little power. This fixes that: It delivers a full 40 amps to our two ~100AH flooded batteries (Walmart 29DC), which will take them from 50% to 80+% charge in less than 2 hours, our usual travel time between sites, eliminating the need to run the generator completely on most days (and we don’t skimp much on electricity, using the microwave and watching movies most evenings and a forced air heater all night). A few tips: 1) It draws 43 amps from the vehicle, so you really need the 4 awg wire to the trailer and a heavy-duty disconnect (we used a 150 amp which works well with 4 awg). 2) At full draw the vehicle battery was at 12.8 volts at idle, so it’s right at the limit: You definitely don’t want to be drawing down the starting battery. This is on a Nissan Frontier with a 130 amp alternator, meaning you also wouldn’t want to use it on a vehicle with a smaller alternator unless you’re sure you’ll always be running it above idle and/or without lights/AC/etc. on. 3) A hydraulic crimper would of course be preferred but I used a hammer crimper which worked fine. Just be sure you shrink-tube the connection since hammer crimpers can penetrate the lugs. To get full thickness into the lugs, either fold the wire in half, run the wires (8 awg from the unit, 4 awg from the line) past each other when making a butt splice, or half-fill the lug with strands cut from your 4 awg wire and then push the line in around them. I connected it to the lugs on our inverter since there were already 4 awg lines running from that to the batteries. 4) Hookup was easy, running a 4 awg line from the truck battery to the bed not so much. I fused it of course, but it’s definitely not something you want to chafe or real drama could ensue. The maximum usable distance from the vehicle to the unit is much longer than what the manual says (e.g., if your batteries are in the back of your trailer), but you must ensure that it’s at least 4 awg all the way. Using vehicle and trailer chassis grounds are fine: You don’t need to run a negative line except for a short one between the truck and trailer frames (i.e., don’t use the hitch as a ground connection). 5) Be sure you disconnect the charging line on the trailer plug. The manual doesn’t mention this, but if you don’t you’ll lose charging capacity because some of your power will feed back through that wire. 6) I used the 15V setting to maximize charging time efficiency. It quickly trips back to 13.6 volts once reaching that (much quicker than our equalizing multistage charger, for example) so no worries about overcharging. With the standard 14.6 volt cutoff you’re giving up significant amount of charging if you only drive a short time. 7) It’s 93% efficient (according to tech support) but does run pretty warm when at full output for a long time. It should be installed in area with ventilation and definitely not in an engine compartment. 8) Redarc tech support was awesome when I had questions about the installation. 666008

Still working great. Sometimes after a long drive our volt meter stays above 12.6 volts full charge until the next morning, something we never saw when using a generator because we never were willing to run that long enough to get a full charge.
Scott R - 07/04/2020


- 331-BCDC1240D

Review from a similar BCDC in Battery Charger

Using it to charge the Sprinter van house battery from the vehicle auxiliary battery. The yellow wire for the solar input is not in use right now. 919825

- 331-BCDC1240D

Review from a similar BCDC in Battery Charger

We installed this product in our diy camper van conversion a year ago. Installation was not difficult. We have made a few trips in our van and the unit is working well so far. 909454

- 331-BCDC1240D

Review from a similar BCDC in Battery Charger

This thing is just great. It is rock solid in construction and function. Everywhere I go now in my Arctic Fox slide in and F350, bu two 100AH LiFePo4 batteries are charging at 45 amps along the way. The fact that the Redarc is weather proof allowed me to mount it outside under the camper skirt running my 4awg battery cables along the bottom of the camper right to it. 827792

Show More Reviews

Ask the Experts about this Redarc Battery Charger

  • How To Choose the Correct Redarc In-Vehicle BCDC Battery Charger for Auxiliary Battery On Vehicle
    In order to choose the correct Redarc In-Vehicle BCDC Battery Charger you'll need to know the amp hour capacity of the battery bank. This would not include the starter battery for the vehicle just the auxiliary battery, the starter battery would get more than enough charge from the vehicle's alternator. Therefore, for a single 12 volt battery you'd need part # 331-BCDC1225D which is rated for 75-200 amp hour batteries (Odyssey PC2150 = 100 Ah). The Redarc In-Vehicle BCDC Battery Charger...
    view full answer...
  • How to Keep Deep Cycle Battery Charged for Winch and Trailer Light Usage
    The positive terminal on your deep cycle battery will connect to the 12V circuit from your 2018 Ram 2500 to provide a maintenance charge and you do ground the battery from the negative terminal to your trailer frame. With that being said, the 12V power from the alternator on your Ram will provide a trickle charge at best (which keeps the battery topped off when not in use) and it won't actually charge the deep cycle battery completely. Since it sounds like you are looking to use...
    view full answer...
  • Installation Kit and Wiring for Redarc In-Vehicle BCDC Battery Charger 331-BCDC1225D
    To install your Redarc In-Vehicle BCDC Battery Charger # 331-BCDC1225D you can use the matching installation kit # 331-FK40 which includes fuse holders, fuses and cable crimps. Based on the 40-amp value of the fuses supplied in the kit you will be fine with 8-gauge wire for a 12-foot run.
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  • Choosing Between The Redarc 25 amp or 40 amp Model For A 2018 RAM Promaster 1500
    Your 180A alternator will work fine with any of their BCDC models. Whether you need a 25, 40 or 50A model will depend on the size of the battery bank you’re planning to charge. If its between 75-200Ah the # 331-BCDC1225D model will be fine but if its greater than 200Ah either the # 331-BCDC1240D or # 331-BCDC1250D will work best to replenish the battery bank faster. Yes, the BCDC can accept unlimited solar Watts/ Amps but its output is limited by the model chosen (i.e. 25, 40 or 50A). Yes,...
    view full answer...
  • Wiring a Trailer With Dual Batteries and Solar Charger
    Let's try and take this one at a time to make things easier; to start with the black wire from the 7-way plug (the 12V) should be run to the pair of 12V batteries you already have in the battery box. In terms of grounding they will be grounded through your Redarc In-Vehicle BCDC Battery Charger # 331-BCDC1225D. The LED lights each need to be grounded to the frame of your trailer; they will also be connected to the 12V batteries which would be connected to the charger. That covers...
    view full answer...
  • Are Redarc Battery Chargers # BCDC1225D and # BCDC1240D Compatible with AGM and Lithium Batteries
    Yes, both of the BCDC Redarc batteries, part # 331-BCDC1225D and part # 331-BCDC1240D, are compatible with AGM, gel, standard lead acid, calcium, and Lithium ion (LiFePO4) batteries. The wiring configuration will be very similar between the two. You will just need a low voltage disconnect when using the Lithium Ion battery as you can see in the attached photos. To get the proper fuses you will need the 40-Amp MIDI Fuse Kit # 331-FK40 for part # 331-BCDC1225D, or the 60-Amp MIDI Fuse...
    view full answer...
  • Parts Needed to Protect Trailer Battery from Overcharge Due to Vehicle Battery
    The 12V power from your 2006 Ford F-150 will actually only trickle charge the battery on your trailer, meaning the charge rate is very slow. If you are using your battery on a regular basis then it would be more beneficial to use a charger like part # CTEK56353 when you are parked than it would be to rely on your alternator to charge the battery. With that being said, we do have a selection of battery charger/maintainers that you can add to your setup to help protect your battery. I...
    view full answer...
  • How to Determine if 2017 Ford E-450 Has Smart Alternator
    Thank you for all of the information! In order for the alternator on your 2017 Ford E-450 to be a smart alternator there needs to be some type of sensor to read loads; this is typically found on the negative battery terminal. If you check out the attached photo I received from Redarc you can see an example of what that sensor would look like. I'll address your questions in order, but the ultimate answer is that the Redarc In-Vehicle BCDC Battery Charger # 331-BCDC1225D (for standard...
    view full answer...
  • Compatibility of DC to DC Charging Trailer Batteries While Operating Refrigerator Off Inverter
    Yes. The Redarc In-Vehicle BCDC Battery Charger # 331-BCDC1225D is designed to allow you to run your inverter and other components while towing. If you need more than the 25 amps and 375 watts for your application, then I recommend the 40 amp # 331-BCDC1240D which will give you 600 watts.
    view full answer...
  • Recommended Wiring Gauge for Redarc BCDC to Dual Battery Setup
    The Redarc In-Vehicle BCDC Battery Charger - Dual Input - DC to DC - 12V/24V - 25 Amp # 331-BCDC1225D has the equivalent of 10 gauge wires for the power from the battery. It is recommend to install the 40-Amp MIDI Fuse Kit for Redarc In-Vehicle 25-Amp BCDC Battery Charger # 331-FK40 along with 6 gauge wire like the Bulldog Winch Wiring Kit for ATV/UTV Winches - 120" Long Power Lead # BDW20307
    view full answer...
  • Recommended Vehicle to Trailer Battery Charger for Trailer Battery
    Without hesitation, I recommend using a 7-way trailer connector and using the 12V charge line you find at the 1 o'clock position to run to a battery charger and then your trailer battery. Most charge lines only take whatever amperage is not being used by the vehicle and sends it to the trailer battery providing a maintenance charge. Your trailer clearance lights will run without issue using either plug and drawing power from your vehicle, so the 7-way will serve you well for that function...
    view full answer...
  • How to Jump Start Vehicle Battery From Aux Battery with Redarc BCDC Charger
    Than you so much for your recent purchase! If you want to be able to jump start your vehicle's battery using the auxiliary battery your best option really is to add the Redarc Smart Battery Isolator (SBI) # 331-SBI12 to your existing setup that includes your Redarc BCDC Charger # 331-BCDC1225D. I reached out to my contact at Redarc and this is the specific isolator they recommended to work with this charger for this purpose. I have attached a wiring diagram that you might also find...
    view full answer...
  • Recommended Trailer Wiring for Solar and Vehicle Charged Trailer Batteries with Inverter
    I can absolutely help you with this trailer. First, I recommend using the Epicord 7-Way Molded Trailer Plug with Junction Box - 10' Long # 277-000141 along with ring terminals # 44-5310A. This will easily allow you to convert your 4-way wiring and also add your trailer brakes using # 10-1-1. Then you can use the 10 inch # AKEBRK-35-SA for the 4 hole mounting flange or 12 inch # AKEBRK-7-SA brake assemblies for the 5 bolt mounting flange. For your charging your trailer batteries from...
    view full answer...
  • Installing Redarc BCDC Battery Charger # 331-BCDC1225D for Charging Trailer Battery
    The Redarc In-Vehicle BCDC Battery Charger # 331-BCDC1225D that you referenced is a perfect option to not only maintain the charge on your trailer's battery but actually charge it up during travel. This is because the charger will provide a continuous output of 25 amps (much more than just running a dedicate wire from the tow vehicle's battery to a 7-Way connector). This particular charger also has the ability to accept power input from solar panels for added efficiency if you ever decide...
    view full answer...
  • Is a Solar Controller Needed to Install Redarc In-Vehicle BCDC Battery Charger
    A solar controller is not required to install the Redarc In-Vehicle BCDC Battery Charger # 331-BCDC1225D, the solar panel does get connected to the charger directly via the yellow wire. As for fuses you will need the 40-Amp MIDI Fuse Kit for Redarc In-Vehicle 25-Amp BCDC Battery Charger # 331-FK40 which gets installed as per the accompanying photos; it will depend on the type of battery (lead acid or Lithium ion) you are using. I have added a link to a video review of this charger...
    view full answer...
  • Charging Trailer When Truck Engine Is Running
    You're correct that the 12 volt power circuit from your truck will not effectively charge a trailer battery that is being used to power hungry electrical loads such as a fridge, lights, inverter, etc. The best way to charge a trailer battery is by using the Redarc In-Vehicle BCDC Battery Charger # 331-BCDC1225D (25A model) or # 331-BCDC1240D (40A model). These products also have an inbuilt MPPT solar regulator and battery isolator function. The solar regulator will allow you to charge the...
    view full answer...
  • How To Charge a Trailer Battery Without Killing the Tow Vehicle Battery
    I know this may be more than you are looking to spend but the 7-way circuit on your tow vehicle is not going to have all the functions are you looking for so your only option to obtain these would be with an actual battery charger, the Redarc In-Vehicle BCDC Battery Charger part # 331-BCDC1225D . The BCDC uses power from the vehicle's alternator so you don't have to worry about it killing the tow vehicle's battery. The BCDC will also provide an actual charge for the trailer battery whereas...
    view full answer...
  • Can Redarc In-Vehicle BCDC Battery Charger be Used to Jump Start Battery
    In addition to the Redarc In-Vehicle BCDC Battery Charger # 331-BCDC1225D you need to use a Redarc Smart Start Battery Isolator. I recommend using the Battery Isolator with Wiring Kit # 331-SBI12KIT if you don't already have the fuse kit, or part # 331-SBI12D if you do already have the fuse kit. With the isolator installed you can then connect a push-button into your system to help jump your start battery.
    view full answer...
  • 12 Volt 5th Wheel Trailer Battery Charge While Towing
    The pin at the 1 o'clock position is the 12V power used to provide the "maintenance" charge to your battery. The issue you found with your F-250 is the same as what you will find with all vehicles. The charge provided to your trailer battery is minimal when driving because even though it is 12V, it is only about 2-4 amps. This is because your vehicle alternator is generating around 14 amps when your truck is running and only the extra not being used to maintain your truck's electrical...
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  • Using the Redarc BCDC1225D Charger to Charge Two Different Batteries
    There is a way to use the Redarc # 331-BCDC1225D charger to individually charge both of your batteries in two locations. First, I would not connect dissimilar batteries together for use or charging. I would complete your truck/refrigerator install as normal except I would put Anderson quick connectors on the black and brown power output. In this way you could connect to either the 110Ah battery in the truck bed, or the 80Ah battery in the trailer. The attached product page has a wiring...
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  • What is Maximum Input Current of Redarc In-Vehicle BCDC Battery Charger # 331-BCDC1225D
    The input current max that the Redarc In-Vehicle BCDC Battery Charger # 331-BCDC1225D you referenced is 25 amps or 300 watts. That's for solar or from other sources as well.
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  • How do I Know if I Have a Smart Alternator?
    The best way to tell is to look for the sensor on the battery. Variable Voltage Alternators require some sort of battery sensing technology to determine load coming from the battery and this is done by a battery sensor which is found on one of the battery terminals (usually the battery negative).
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  • Using Redarc BCDC Charger to Charge Secondary Battery on GMC Yukon
    The Redarc In-Vehicle BCDC Battery Charger # 331-BCDC1225D that you referenced is exactly what I recommend for this application and it will work perfectly. This charger is specifically designed to not just maintain but charge up a secondary battery while driving with its multi-stage charging design that boosts the charge (up to 25 amps) from the truck's battery. Even if the secondary battery were to get low on power you don't have to worry about any damage being done to the alternator....
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  • How To Charge a Trailer Battery For Refrigerator While Driving Down the Road
    In order to charge a trailer battery while driving you really only have one option which is to use the vehicle's alternator. In order to do this you need a device sophisticated enough to take the correct amount of charge without causing issues to the vehicle's battery while also ensuing your are not overcharging the trailer's battery. Furthermore, you will need to isolate the two batteries so there aren't any issues with shorts. For this, we have the Redarc In-Vehicle BCDC Battery Charger...
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  • What Is Needed To Charge a 12 Volt Battery On Travel Trailer
    In regards to charging a trailer battery, you have a few options. The best option to ensure you have a full battery each time you are ready to setup and camp would be a DC to DC powered battery charger which uses the vehicle's alternator. The Redarc In-Vehicle BCDC Battery Charger part # 331-BCDC1225D is what I recommend. The other options entail running a charge line through the trailer connector from the vehicle battery but this requires a 7-way like part # ETBC7L (charge line included)...
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  • Where Does Low Voltage Disconnect Wire Into Redarc DC to DC Charger
    I attached a picture with an arrow pointing out where the low voltage disconnect would wire into the Redarc DC to DC charger setup part # 331-BCDC1225D that you referenced. We do not carry a product for this but they are available elsewhere.
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Info for this part was:

Expert Research:
Mike L
Expert Research:
Jameson C
Expert Research:
Adam R
Edited by:
Lindsey S
Installed by:
Jeff D
Video by:
Joshua S
Video Edited:
Chris R
Updated by:
Sarah W
Updated by:
Kristina F
Updated by:
Matthew E
Updated by:
Noah M
Test Fit:
Brent H
Written by:
Brian T

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