Recommended Wire Gauge for Redarc 331-BCDC1250D In-Vehicle BCDC Battery Charger

Updated 11/18/2021 | Published 07/08/2020

Question:

Should I endeavor to go larger if the BCDC is within 6 feet of the battery bank? According to calculation charts online, the only way I can stay within an acceptable voltage +/-1.5 from the front battery/alternator to the rear of the vehicle where the BCDC is located is to run 1/0AWG for no more than 15 feet. At this point, what is the most effective way to join the 1/0 cable with the BCDC cable looks to be 10AWG? without introducing more voltage ? And should I run 1/0 from the other BCDC cables green/brown/yellow to the batteries/solar panel - no matter how far away they are - to again avoid more voltage ?

asked by: Sam J

Helpful Expert Reply:

It's recommended you place the charger as close to the battery being charged as is possible.

According to my contact at Redarc, if the wire length will be 3-16 feet, 6 gauge cable is recommended. If that distance is greater than that, say between 16 and 30 feet, 4 gauge cable is recommended. Per Redarc, if you stay within those guidelines, the voltage drop wouldn't be an issue.

I've linked to a product demonstration video featuring the Redarc # 331-BCDC1250D charger.

expert reply by: Mike L

click to enlarge

Mark

11/12/2021

Currently have a redarc DC charger charging a second battery in the front of 4wd I have 6 g wire running to the rear of the car 3 MTRS from the second battery. The second battery runs a fridge. I have a camper with 2 batteries and a redarc DC charger. I want to connect the trailer DC DC charger to the wires at the rear of the vehicle which are from the secondary battery. Is this ok or do I need to run a new set of wires from the starter batter to the rear and then subsequently to the trailer DC charger. PS Al fused with 30amp

Victoria B.

11/18/2021

@Mark I reached out to Redarc about the best way to hookup a second BCDC Charger for your camper's batteries. They recommend wiring the trailer's BCDC to the starter battery, not to the auxiliary battery that is already charged with a BCDC. This would require you to run a new set of wires from the starter battery to the rear of the vehicle to a connector to hook to the wiring on the trailer. If your vehicle has a smart alternator, which were put on most vehicles from 2003 on, Redarc also recommends installing a 60-Amp Relay Kit # 331-RK1260 so the charger will recognize the smart alternator without a direct connection to an ignition source.