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Keep your trailer's battery charged with this single-input, DC-to-DC smart charger. Unit installs in your vehicle or trailer and pulls power from your vehicle battery to charge your auxiliary battery. Great for dump trailers and pop-up campers.
Features:
Specs:
The Redarc BCDC single-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.
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.
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.
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 12.0V, as opposed to the standard 12.9V.
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 dump 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:
To ensure a low-resistance connection, you will want to use MIDI fuses (RED76FR or RED86FR - 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 - sold separately) below:
For a typical Lithium ion (LiFePO4) battery setup, refer to the wiring diagram (shown with fuses and optional LED - sold separately) below:
California residents: click here
Detailed and easy to follow instructions. Materials feel like quality stuff.
I absolutely love this device... I installed it on our dump trailer where the most embarrassing thing is when your battery dies while trying to dump at the recycler... (everyone hates you!) This unit keeps the trailer battery always topped off, we are in and out quicker and no more people shaking their heads because you're tying up the space. We installed it with an indicator light so we know when it's working. Easy install. The only suggestion I would make is for the unit to come with circuit breakers so the buyer doesn't have to hunt them down when doing the install. Again.. Love the unit!!
Easy, straightforward install. Getting 14.6 V at the dump trailer battery when charging. If it stays trouble free, would highly recommend.
Product works as expected to maintain marine battery installed in car hauler. Battery powers winch and interior lights. Redarc charges the battery while towing without overloading charge circuit on truck. Installation was easy. Installed for one year. Very pleased.
I installed this in a 2017 Oliver Legacy Elite II travel trailer, because I had installed Battle Born lithium batteries and there was no way my truck was going to charge them properly. The actual installation was fairly painless, but I had to run bigger wires from the front of the trailer back to the batteries, which are located over the axles. I get a solid 10.5 amps continuously now, even though my Land Cruiser is only putting out 13.5 volts when connected. It works as advertised and I do recommend it. I took one star off because I think it is over priced, but that is be expected for an Australian import.
Using this as a current limiter to charge an auxiliary battery on my auto hauler. Wiring is extremely simple for a standard 14v application. Small unit that fit easily in the tongue box.
Patrick 
4/15/2024
Still works as designed.
I installed this on my 2015 Airstream with my 2020 F-150 and love it! The 96 FR will work with the 7-pin trailer harness and the F-150, so there is no need to run bigger wires. The truck has a 25 amp fuse on the charging circuit to the 7-pin trailer harness, and the 96 FR is current limited to 20 amps, which is perfect! The F-150 has a smart alternator that reduces the output voltage when the truck is under load, so without the 96 FR the truck would do very little charging of the trailer batteries while driving down on the road. I love it!
Dan
11/28/2023
Great! The only issue so far is that the unit locks out when the temp is below 10 degrees F. I live in Wyoming and typically leave to go camping in the winter when it’s often subzero. I sometimes drive most of a day before the Redarc warms up enough to turn on. My Redarc is mounted under the bed, inside my camper.
I have put close to 50k miles on my trailer after installing this unit running hotshot. It worked great for keeping the battery charged off of the truck power. I actually have another trailer I have been planing to order another one for so I'm able to hook up a batter and run utility lights in as well as battery chargers.
I'm charging a house battery that powers a 12 volt refrigerator. Very simple install. Not giving this unit a 5 star rating because the 12 volt input and charging wires exiting the unit are 12 gauge wire and they get fairly warm to the touch. The instructions that come with it list 10 gauge wire as the minimum wire size to use to connect it.
Rbberfish
5/28/2022
Still working and Im happy with the job it does.
Most modern 1/2 ton pickups have "energy efficient alternator" as part of the battery management system. That means if the battery management system senses that your truck battery is fully charged, it lowers the output of the alternator. This means that the alternator voltage is insufficient to charge the camp trailer battery. This Redarc device will take the lower voltage from the alternator and boost it up to charge the camper battery. It works as intended and solved a big mystery for me as to why the camper battery didn't gain charge during long drives from one campground to another
This gadget is awesome. It solves two problems. (1) How to charge your camper battery when it is at the end of a long line from car to camper with attendant voltage drop. The Redarc boost the voltage back up to a proper battery charge level. (2) When you shut the tow vehicle down, the Redarc protects the tow battery from discharge into the camper system. Has worked fine for me.
Overall, I think giving the product itself 4 stars is a correct evaluation. I want another evaluation of 5 stars given to the support staff at Redarc. The charger itself has not given me the slightest issue as far as reliability goes. The fact that it came with a temperature sensor in the device that shuts off charging at its own temp of 0°C (freezing temp) on Lithium charging mode came as a complete surprise to me. By reading the documentation that came with the charger, I didn't discover it shuts off automatically at freezing temperature. When I noticed I could not charge my LifePo4 battery at below freezing. Thanks Redarc staff for telling me about this after I asked about it.
This worked exactly as I hoped. I needed something to limit the current coming out of a cigarette lighter so I could charge a lithium battery from that lighter. Worked perfectly.
eTrailer was helpful in showing me this solution.
I searched long and hard to find something like this. Strangely enough its not easy to find unless you contact etrailer. In no time they recommended this charger and it was spot on for my needs. Etrailer will get my business in future
Fast shipping, excellent
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Brooke M.
3/27/2025
We would definitely be interested in what you think once you have some time to use it! Keep us in mind once you've gathered some data. :)