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

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

Item # 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 chargers part number 331-BCDC1225D 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 - 25 Amp. Battery Chargers reviews from real customers.
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Redarc Battery Chargers - 331-BCDC1225D

  • Redarc
  • Battery Charger
  • Vehicle Battery to Auxiliary Battery
  • RV/Camper
  • Trailer
  • DC to DC
  • Charges/Maintains
  • 12V
  • 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

331-BCDC1225D Installation InstructionsInstallation Details 331-BCDC1225D Installation instructions

California residents: click here

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

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

Video Transcript for Redarc In-Vehicle DC to DC Battery Charger Installation

Speaker 1: Today we'll be having a look at, and showing you how to install the Redarc In-Vehicle DC to DC Battery Charger with dual inputs, part number 331-BCDC1225D. Now the main reason you're going to want a batter charger like this one installed in your trailer is that this will maintain and charge your batteries in your trailer up to 100%, making sure they are fully charged when you arrive at your destination. Unlike our traditional charging systems that we run through the 7 way connector on the front of your trailer, those only get your batteries to about 80% of their capacity. This will get you all the way there.This charger will work with 12 or 24 volt battery systems. It will provide up to 25 amps of power output to maintain the charge of your batteries. This battery charger is compatible with your standard alternators from your tow vehicle, as well as variable voltage, or what are commonly known as smart alternators as well.

This charger is a dual input battery charger. It does DC to DC charging, and the way that works is when you're hooked up to your truck, it will use the alternator to fully charge your batteries. Additionally, you can hook up a solar panel to it, to maintain the charge of your batteries, and fully charge them when the trailer is not even in motion and is sitting parked. If you have a solar panel installed, it will use that to its fullest ability before taking any additional power from your tow vehicle. If you do decide to hook this up to a solar panel, it will work with unregulated solar panels that supply between 9 and 32 volts of power output.To begin our install, we need to locate the batteries that we want to be charged while driving.

In our case, we're working on a fifth wheel trailer, and our batteries are in the front storage compartment. We'll need to locate a spot to mount our charger, where it will be able to make our connections to our batteries using our cables. We've chosen this area here against the bulkhead of our trailer. It's right behind both of our battery boxes, so it gives us easy access to the batteries to make our connections, and it will be out of the way of any cargo that is stored in this compartment.We'll start by marking our bottom location where the holes go, to secure it into place. Okay, with the bottom locations marked, we can get the charger out of the way, and we'll make 2 pilot holes there.

We'll now secure it into place using 2 self-tapping screws. We'll put 2 in the top, just to help support the weight. You will have to provide your own self-tapping screws. Now we need to find a way to get a power cable like this to our charger that we'll be able to attach to our vehicle that's doing our towing. In our case, we're going to route our cable along side this 7 way wire, that goes to our truck, and we'll have another attachment point on our truck next to the 7 way, where we can plug the power in next to it.Your application may vary from doing this on a fifth wheel, or a standard trailer, or any other type of trailer.

What we're going to do is we're going to have a pull wire that we've already routed through here, next to where our 7 way cable comes out, into our battery compartment, and we'll use that to pull our power cables through. Here we got our cable pulled through now, and we have it zip-tied to our 7 way wire, so we'll have 2 leads sticking off, one being our positive and one being our ground, and we'll have 2 separate connectors that will plug into the back of our truck.In order to make our connection to our truck that's pulling our trailer, we're going to install a wench connector here. It's a quick disconnect, and this will allow us to easily plug into our truck and unplug quickly and easily. This for 6 gauge wire, and we're using 6 gauge wire on our install here, so these are going to work great for us. We'll start by cutting off some of the insulation from our wire. Use a utility knife to do this, or you can use a pair of strippers if you have one that will work on wire this thick. Once we have it cut, we'll be able to pull it off. We'll twist our wires together nice and tight. We'll take one of our connectors, and we'll place it on the wire, making sure all the wires go inside of it. Now, we'll use a crimping tool to crimp it into place. We're using a hydraulic crimper for this. These are readily available at most hardware stores. Here's what it looks like once it's crimped. Now we'll repeat this same process for our other cable.Now we'll take our plug here with the lanyard, we'll slide it over one of our wires. It doesn't matter which one. This orange wire here is our positive wire, that will go to the positive side of our terminal. As you see, there's a positive side and a negative side. We'll take our wire with the terminal crimped on, and insert it in the back end of our connector, and we'll push until it clicks into place. You can see our terminal comes out all the way, once we have it clicked in, so now we'll do the same for the other wire. Now we can take our dust cover, place it over the end and this will protect our connector when it's not in use.Now we'll cut off the insulation from the other end of our wires that we added. On our power wire, the orange wire that we're using, we'll take one of these copper butt connectors, which you'll have to supply your own. They're readily available at most electrical supply stores, and we'll use our crimper to crimp it into place. Here's what it looks like once it's crimped down. Redarc does highly recommend that we solder and heat shrink our connections. I will go ahead and get some solder inside of there, and then I'll slide our heat shrink on over this wire right here, before we crimp it onto the other end.We have some solder inside there now, so we'll take our heat shrink, we have some available on our website, if you need it, and we'll slide it down over our wire just enough so we have access to the other end of our connector. Now the other end of our butt connector on our orange wire will go to the red wire on our charger, so we'll insert that into the butt connector, and we'll crimp it into place. Now I'll pull back and make sure it's secure. Okay, with both of our wires now crimped together, we'll slide the heat shrink over the connector, and we'll shrink it into place using a heat gun versus a lighter, because this is a source of indirect heat, and it will more evenly shrink down our heat shrink, and won't damage it.Now we'll take a 6 gauge, 3/8 of an inch diameter ring terminal, which we have available on our website as part number SWC57016, and place it over the end of our black wire. This is our ground wire, and we'll crimp that into place as well. Some heat shrink over that connector as well, and we'll shrink it into place. Okay, and now the black wire that we put the ring terminal on, we need to attach it to a chassis ground. Our chassis ground goes directly to the negative post on our battery with this wire here, so if we remove this nut and place it on there, it will be grounding not only into our battery, but our chassis ground as well, providing us a superior ground connection, so that's what we're going to do.Now we have about a 3 or 4 inch section of our 6 gauge orange wire that we're using for our power wire. We'll strip back the insulation from both ends. Okay, I'll do the same for the other end. On one end of our stripped back wire, we'll place on one of our 3/8 ring terminals, and we'll crimp it down. On the other end, we'll attach a Redarc fuse holder that we have available on our website as part number 331-FK40. We'll take one of the ring terminals from that kit, stick that on the other end, and we'll crimp that as well. We have a nice, solid crimp on both ends. Now we'll take our fuse holder, place on our 40 amp fuse, and on one end, it doesn't matter which, we'll attach the smaller diameter ring terminal that comes with the fuse holder, to one of the studs, and install one of the nuts, and tighten it down.The brown wire that comes off of our charger, we'll place on one of the small ring terminals from our fuse holder kit, and we'll crimp that into place. We'll solder this connection and heat shrink it in. Now we will attach the brown cable to the other end of our fuse holder. We can now close the cover over the holder. This end here, we need to connect to the positive terminal of one of our batteries. Our batteries are interconnected, so this will charge both of them. Now connecting this to our battery is a simple process of just removing the nut, placing it over the stud and reinstalling the nut.Now depending upon your application, you may or may not need to do this step. The black cable that comes off of our charger needs to go to a ground. In our case, we're going to attach ours to the negative terminal of the battery because there is a large diameter wire that goes to the chassis ground from there, and it will still serve the same purpose. We're going to make an extension cable, just so we have enough room to route our wire cleanly, and to make the connection. On one end we'll place one of our 3/8 of an inch diameter ring terminals, and we'll crimp it into place. The other end of our extension cable, we'll attach a 6 gauge butt connector to. Now we'll attach our extension cable that we made to the black wire off the Redarc unit. Solder and heat shrink the connections. We'll do that for the rest of our connections from this point forward.The black wire, we need to attach to a chassis ground. Our chassis ground's over here via this white wire, and it goes directly to the negative terminal of our battery, so we could also attach this to the negative terminal of our battery and we'll accomplish the same purpose, so that's what we're going to do. Remove the nut, place this on, and reinstall the nut.Okay, now we have four wires left from our charger. We have a blue one, a green one, an orange one and a large, yellow one. The large yellow one is for hooking our charger up to a solar panel, so when we're not towing our trailer behind our truck, we can also still maintain the charge in our batteries, and have them fully charged at all times, with the solar panel, which is sold separately. We are not going to be using a solar panel on this trailer, so we will cut off the exposed wire. We'll come back to that in a minute.The green wire here is for an optional charge status LED indicator, which will tell us the status of what's going on with the batteries, and how they're being charged. We're also not going to be using this, so we'll do the same thing.The orange wire here is for our charging profile selection, and the way that this works, if we connect the orange wire to a common ground, we'll have a maximum charging voltage of 15 volts. If we connect it to the red wire from our charge unit, we'll have a maximum charging voltage of 15.1 volts, and if we're going to be charging lithium ion style batteries, we can connect this orange wire to the green wire for the LED output, and this will set it to lithium mode. The last way is that we can leave this disconnected and this will have our maximum charge voltage to 14.6 volts, which is just above what the maximum output is for the alternator on our truck, so that's where we're going to have this. We're just going to leave it disconnected.This leaves us with our blue wire. This is our trigger wire. This tells the charger how to work properly. Now this only applies if your vehicle has a variable voltage alternator. The truck that we're towing this trailer with does not. It has a standard alternator, so we'll be leaving this wire disconnected.Now that we have all of our exposed wires cut off that we're not going to use, we'll place some heat shrink over them, to protect them from grounding out. That way, if we ever change our tow vehicle to one that has a variable voltage alternator, we can hook up the low voltage trigger wire. Here's what it looks like bundled up. We put some loom here, used some tape and some zip ties to secure all the wiring, and our heat shrink ends, we put inside this loom here, just to secure them up out of the way, and to make everything look nice and clean.Now we find ourselves underneath the hood of our vehicle that's doing the towing. We need to have a power cable that goes from our battery to the back of the truck to make our connection. We have our power cable, as well as our ground cable, zip tied up to the battery cable of our tow vehicle, and then we routed down through our engine bay, making sure we avoid any moving parts, and sources of heat.You can see the orange and black wires that we brought down from our engine compartment. We just follow the factory wiring harness going towards the back of the truck, securing it along the way with zip ties. At this point, the wiring harness now goes inside the frame. Here's where it comes over the frame. We're still securing it to the wiring harness. The wiring harness then goes inside the frame, along side the fuel tank. We fish-wired it along there. Once we reach the end of our fuel tank, you can see the wiring harness again. It continues tying to it, goes behind our shock mount, goes along side our spare tire. We have it zip tied to the wiring harness here, and then down to the bottom of our 7 way bracket.To begin our install, we'll need to remove some of the insulation from our wires, so we use a utility knife, just to cut away our insulation a little bit. Once we've sufficiently cut around it, we'll be able to pull the end of it off. We will do the same for the other wire. Now we'll take our connector, our terminal end, and place it on one of our wires. It doesn't matter which one. Get it all the way on there, and then we'll crimp it into place. Okay, pull back and make sure it's nice and secure, and we'll do the same for our other wire. Now we'll take our quick disconnect housing, we'll pull off the cover.On the end we have a lanyard. We'll slide that over one of our wires. It doesn't matter which one. You'll notice there's a positive sign and a negative sign. We'll attach the positive to our positive cable, which in our case is the orange one here, so it will be this one. To do that, we'll just slide the cable inside of the connector, and push. When you hear it click, you know it's secure, and the negative, we'll attach the negative, which is our black one. Okay, once it clicks in, we'll pull back on both to make sure both of our cables are locked into place, which they are. We have our cover, which we can slide over, so when it's not in use it will be protected from the elements.We need to install a fuse to protect the charger and the wiring, so in case a short we're to happen, we wouldn't risk damage to the charger or our vehicle or trailer. We'll take our wire, and we'll measure off a few inches from the end of it, and cut it. We can install the Redarc fuse kit, which is part number 331-FK40.Now we're going to cut off some insulation from all three ends of our wire. I'm just using a utility knife to do this. If you have wire strippers that are big enough to do this, that's good. I don't, so I'm just using a utility knife. Okay, now that we have it cut, we'll pull off the end, and we'll twist the wire together, nice and tight, and we'll do the same for the other two ends.Now we'll take one of our ring terminals that comes with out kit, and we'll stick it on the long end of our cable. I'll stick it down all the way, and we'll crimp it into place. We did the same for one of the other ends of our short cable. Now on the other end of our short cable, since we're using 6 gauge wire, we're going to attach a 6 gauge ring terminal, with a 3/8 of an inch diameter hole, part number SWC57016, on our website, and we'll use our same crimping tool to crimp that into place.Okay, now that our connection is soldered, we'll have a great electrical connection that's nice and solid. We'll take some heat shrink, and we'll cover up our solder joint and our cable, and we'll use a heat gun to shrink it down. We'll repeat this same process of soldering and heat shrinking all of our connections from this point forward.Now we'll take our fuse holder, remove the nuts, take a provided 40 amp fuse, place it over the studs, and we'll place our terminals over the studs and reinstall the nuts. We'll use an 8 millimeter socket to tighten our nuts. Now we'll take our cover, and we'll fold it over our connections, and it will snap closed, and lock into place. Now we'll remove this nut on our positive battery post, place our ring terminal over the stud, and we'll reinstall the nut.Now that we have our power side hooked up to the positive terminal of our battery, we'll need to make a connection with our ground wire here, to the negative side. We'll cut off some insulation. Now we'll place on one of our 3/8 ring terminals that we have available on our website. Just like we've done with all of our other connections, we'll solder and heat shrink them. We'll remove the nut from our negative battery post, we'll now place our ring terminal over the bolt and reinstall the nut. Okay, that's nice and secure.That completes our look at and showing you how to install the Redarc In-Vehicle DC to DC Battery Charger with dual inputs, part number 331-BCDC1225D.

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   (19 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

- 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

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

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

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

- 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

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

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

- 331-BCDC1240D

Review from a similar Redarc BCDC in Battery Chargers

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

Review from a similar Redarc BCDC in Battery Chargers

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

Review from a similar Redarc BCDC in Battery Chargers

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

Review from a similar Redarc BCDC in Battery Chargers

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

- 331-BCDC1240D

Review from a similar Redarc BCDC in Battery Chargers

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

Review from a similar Redarc BCDC in Battery Chargers

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-BCDC1240D

Review from a similar Redarc BCDC in Battery Chargers

Have not installed the Redarc in my camper yet, but really appreciated the quick turnaround on my order. Quick shipping was better than Amazon. 728803

- 331-BCDC1240D

Review from a similar Redarc BCDC in Battery Chargers

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


Ask the Experts about this Redarc Battery Chargers

Do you have a question about this Battery Charger?

  • 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...
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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,...
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  • Recommended Truck Camper Dual Battery Charging System
  • The NOCO Genius Mini On-Board Battery Charger - AC to DC - 2-Bank - 8 Amp # 329-GENM2 will work for a shore power to batter power charger for batteries up to 120 amp hours. If your batteries are larger then you will need the NOCO Genius On-Board Battery Charger - AC to DC - 4-Bank - 40 Amp - 12V # 329-GEN4 to charge batteries up to 230 amp hours. Most truck campers will instead use a DC to DC charger for the camper batteries. If your batteries are under 200 amp hours, I recommend the...
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  • Why is Relay Kit for Redarc In-Vehicle BCDC Battery Charger Needed for Smart Alternator
  • The 60-Amp Relay Kit for Redarc In-Vehicle BCDC Battery Charger # 331-RK1260 is needed - but not necessarily required - for use with the Redarc In-Vehicle BCDC Battery Charger # 331-BCDC1225D (25 amp) or # 331-BCDC1240D (40 amp) with a smart alternator because those chargers require starter battery voltage and running an ignition feed to the charger can be difficult. Your example of a long run to a trailer is on the money and exactly what it would be needed for. I have added a cut out...
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  • 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...
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  • 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...
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  • Recommended Mounting Location for Redarc DC to DC Battery Charger # BCDC1225D
  • It is advised to install the Redarc In-Vehicle BCDC Battery Charger # 331-BCDC1240D or # 331-BCDC1225D in your trailer and not your truck. I've attached videos of this installation to assist. Specifically we put this product in the front storage compartment of the RV to be close to the wiring that connects to the vehicle and also the trailer battery because the unit installs between those two components. The In-Vehicle refers to the trailer and not the tow vehicle so you can use the...
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  • How to Charge Up a Trailer Mounted Battery While Driving
  • The 12 volt circuit on a 7-Way trailer connector is not adequate for charging up a trailer mounted battery. At best it can maintain the current charge in the battery assuming nothing is drawing power from it. Solar power takes a very long time to charge up a typical 12 volt car-type battery so it will need a little help to charge up the battery. Take a look at the DC to DC charger # 331-BCDC1225D. With this unit you can actually charge up the trailer battery while you drive. It has inputs...
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  • Recommendation for Charging a Lithium Battery Bank From a 2009 Ram 3500 Diesel Tow Vehicle
  • The Tow Ready Battery Isolation Solenoid # TR118665 along with 00 gauge wire and Pollak Single-Pole, Round Pin Trailer Wiring Socket # PK11851 along with # PK11852 will allow you a great connection for charging your battery. I also recommend putting a 40 amp circuit breaker # 9510 in line to protect your system. The issue is it will not amplify your charge so you will still be limited to the 2-3 amps charging above what your truck uses from your alternator. For a better option, I recommend...
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  • Recommended Vehicle to Trailer Battery Charger with Solar Power Option
  • The CTEK battery charger # CTEK56353 is a great charger for when you have shore power, but will not work for a vehicle to trailer battery charger. To charge your trailer battery from your Outback 2.5i, you will need a different type of charger. If you are a fan of the CTEK brand, then you would want the CTEK D250S Dual Battery Charger 12V- 20a, 5 step, Heavy Duty # CTEK40186. This will allow you to use your vehicle battery to charge your trailer battery without draining your vehicle...
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  • Travel Trailer Battery Charging from the Tow Vehicle 7-Way
  • When your trailer is connected to a 7-way like the Pollak Metal 7-Pole, RV-Style Trailer Socket - Vehicle End # PK12703 the pin at the 1 o'clock position is the 12V power that will charge your trailer battery when it is connected to the corresponding pin on your trailer side connector. This will give your trailer battery a slight maintenance charge that is about 2-4 amps depending on what your alternator can put out that isn't being used by your tow vehicle. This will be like a trickle...
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  • Types of Battery Chargers for Auxiliary Battery on Dump Truck/Trailer
  • We do offer battery chargers, including AC-powered unit like NOCO Genius # 329-GEN2 and DC-powered types like Redarc # 331-BCDC1225D, as well as Solar panel chargers like # PTW2997 that help maintain your auxiliary battery whenever sunlight is available. The vehicle wiring kits we sell are generally limited to passenger vehicles to allow them to tow recreational trailers. If you are looking for a heavy-duty wiring kit to deliver power to your dump bed motor this would best be sourced...
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  • Recommended Battery Charger for Battery to Run Roof Vent w/ 12V Fan
  • If you are wanting to power the MaxxFan Deluxe Roof Vent w/ 12V Fan # MA00-05100K from your trailer battery that is being charged by solar panels, I recommend taking a look at the Redarc In-Vehicle BCDC Battery Charger # 331-BCDC1225D. This is a great DC-to-DC, 25 amp battery charger that features dual-input that allows you to connect it to solar panels. When connected in this manner, this particular charger will automatically draw power from the panels before tapping into the vehicle power...
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  • Recommended Trailer Battery Charging System for Enclosed Motorcycle Trailer for Tools and Mattress
  • You can absolutely use a battery in your trailer to do all the things you desire. You will simply want to get a deep cycle battery and get the amp hour rating you desire. The CTEK D250S Dual Battery Charger 12V- 20a, 5 step, Heavy Duty# CTEK40186 along with the discontinued CTEK SmartPass Energy Management Unit for CTEK D250S DUAL Battery Charger CTEK56676 are a great combination for that as the D250S alone will not work well on the high-capacity deep cell batteries. Instead...
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  • Does 2017 Chevy Colorado Have Smart Alternator
  • According to my research yes, your 2017 Chevy Colorado does have a "smart alternator" although you will want to verify this. There should be a sensor on the post of your battery terminal if you do have a smart, or variable voltage, alternator. If so then you would need the 60-Amp Relay Kit # 331-RK1260 to use the 25 amp Redarc In-Vehicle BCDC Battery Charger # 331-BCDC1225D.
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  • 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 # CTEK56158 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...
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  • Recommended Solar Panel Connection for Furrion Prewired Solar Connection on Trailer
  • The 2.5-Watt Solar Battery Charger # PTW2997 is a great option for your solar charging needs on the go. This product will not completely supply the needs of your Furrion camera system but can be used along with a battery to charge the battery so the battery can power the unit. I recommend the Redarc In-Vehicle BCDC Battery Charger - Dual Input - DC to DC - 12V/24V - 25 Amp # 331-BCDC1225D which will allow you to have power from a solar panel amplified and will amplify the trailer battery...
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  • 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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  • 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...
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  • Recommended Trailer Battery Charging To Allow AC, Refrigerator, and Landing Gear To Function
  • When your trailer battery is properly charged, you should not need your vehicle connected or shore power to un your landing gear. Your trailer battery is most likely not getting the charge it needs. From your 14.28V you are getting from your 7-way connection, that will only provide a small maintenance charge to your battery and won't allow it to get over 80 charged. You would need to use a battery charger when not towing to get it up to full power to run your landing gear, fridge, and...
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  • 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.
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  • Battery Charger for Trailer-Mounted Auxiliary Battery
  • A trailer breakaway battery charger kit like # 20011 will be needed only on a trailer that does have electric drum brakes and a breakaway system like the Hopkins # HM20001. For maintaining a trailer-mounted battery that supplies power to lights, vents, etc you can use the 12V power circuit in the 7-way connector. This 12V feed is carried on the pin at the 1-o-clock position as you view the 7-way socket. Please refer to the linked photo and article. This 12V feed has enough power to...
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  • Installing 7-Way and Wiring for Auxiliary Battery Charging
  • For your 2003 Ford E150 hi top conversion van, because you have a 4 way connector, you can use the Adapter 4-Pole to 7-Pole and 4-Pole # 37185. This will connect to your 4-way and then you can simply connect the white ground wire to a bare metal surface and then use # 10-1-1 sold by the foot to connect the black wire on the connector to circuit breaker # 9510 and then to the positive terminal on your vehicle battery. This will get your vehicle ready to send the 12V power. Then on your...
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  • Recommendation for Charging Trailer Battery from Towing Vehicle
  • You can connect your deep cycle AGM 75AH trailer battery directly to your 7-way 12V power for a small maintenance charge. This normally will only give you about 2-4 amps charge because your vehicle is needing the other amps produced from your alternator to maintain your vehicle functions. Only what is not used by the vehicle is available for the trailer battery. This also will not allow a full charge to your battery but will charge it up to about 80% just like a trickle charger, where...
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  • Installing a Trailer Battery Charge Line from Vehicle Trailer Connector
  • To charge your trailer battery when you look at the 7-way trailer-side connector the 11 o'clock pin will mate up to your 12V signal from your vehicle. With most trailer connectors like # H20043 this will be the black wire. That black wire simply connects using 10 gauge butt connector like # DW05745-5 to 10 gauge wire sold by the foot # 10-1-1 which will connect to your trailer battery positive terminal. As you stated the negative terminal of the trailer battery will be connected to the...
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  • 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...
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Info for this part was:

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

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