How To Attach the Redarc In-Vehicle BCDC Battery Charger To the Start Battery

Updated 04/30/2020 | Published 11/06/2019

Products Featured in This Question

Redarc In-Vehicle BCDC Battery Charger - Dual Input - DC to DC - 12V/24V - 50 Amp

(91)

$639.15

60-Amp MIDI Fuse Kit for Redarc In-Vehicle 40-Amp BCDC Battery Charger

(22)

$90.00

Bulldog Winch Rear Wiring Kit - Quick Connect to Terminal End - 2 Gauge - 20' Long

(8)

$351.99

Question:

My Truck: RAM 3500 with Dual batteries and battery chargers. My Fifth Wheel: Big Horn 3760 EL with upgraded AGM battery Bank of 360 Amps. Where should I install this battery charger? I assume next to the battery bank, if so, then what size wire should I use to feed it from my Truck battery? I believe your chart stated a size 4 wire. If this is so, what type of connector should I use to plug into the truck from the RV similar to the standard 7 wire connector presently using? Thank you for your help on this. It appears that I will have two cables instead of one connecting the truck to the RV, is this a correct assumption? If so, then I will need to run a separate cable from the Truck battery to the cargo area where I would then connect the separate cable coming from the RV Pin to the the RV batteries. Please confirm my assumptions. Thank you, Don

asked by: Don A

Expert Reply:

The Redarc In-Vehicle BCDC Battery Charger part # 331-BCDC1250D needs to be installed on the trailer, next to the service/auxiliary batteries. That said, this now means you must run a wire from the Redarc In-Vehicle BCDC Battery Charger to the start battery in your vehicle. The correct size wire to use will vary based on total length as you mentioned. I recommend you go pretty large so you don't have to worry about issues with length or voltage drop. We actually have a kit that will work for this purpose, the Bulldog Winch Rear Wiring Kit part # BDW20206 which includes quick disconnects as well.

In regards to the number of cables you now have between the truck and trailer, there will indeed be two. There is one cable for the trailer lighting functions and then one cable (above) for the battery charge line. Please note, you will also need the 60-Amp MIDI Fuse Kit for Redarc In-Vehicle 40-Amp BCDC Battery Charger part # 331-FK60 but that should do it.

expert reply by: Conner L

Clayborn L.

4/27/2020

Well this start the truck when the batteries get low so it will charge them back up

Chris R.

4/28/2020

Are you asking if the BCDC can be used to jump start a dead battery? It's not a good option for that on its own, but you can add the Smart Isolator # 331-SBI12 to this setup and it'll be perfect. The blue override wire on the Isolator can be connected to a push-button switch to create a bridge of power from the aux battery to jump start the dead battery in the truck.

Clayborn L.

4/29/2020

You know I want to know if when the batteries get low before they die will it start the truck up automatically so that the batteries will stay charged up and shut the truck off when the batteries are at full charge automatically or do I have to do it manually