Forum Discussion

191124x7's avatar
191124x7
Explorer
Jan 08, 2019

Can I run my WFCO output to a REDARC BCDC?

My 2019 Brookstone 395RL currently has a: WFCO WF-9875 75 AMP POWER DECKMOUNT CONVERTER - 55-4708

I'm in the process of adding a REDARC BCDC1240D... and running #2 AWG from my 2019 F-350 DRW's battery (I have the dual extra heavy duty alternators); and plan to connect it to the battery side of the BCDC.

Additionally I'm installing 960W of solar panels on top of the rig.

All of this will be charging 400ah (4 100's in parallel) AGM batteries.

I'm sorry this is kind of a complex question, but here it is in parts...

1. REDARC says that it is 'best' if the WFCO is not in the game. That the BCDC and WFCO might sense each other's voltage and force each other into float mode.

2. So if I shut off the WFCO at the circuit breaker, I'm assuming all is well... as long as there is sufficient sunlight to keep the batteries going and/or the truck is plugged in and running.

3. However, if I'm under trees and in clouds, and the truck is off, I will eventually run out of battery power. So in that case I'd like to turn on the WFCO... and shut off the BCDC input to the battery.

4. My first idea was a DC transfer switch; but I can't find one.

5. So my next idea was... what if I take the output of the WFCO and feed it ONLY and DIRECTLY into the DC input on the BCDC?

Finally my questions:

- I guess the first question is... will this even work? Like, am I right back in the same boat where the WFCO will go into float mode sensing the voltage from the solar/truck? But at this point do I even care because if it does, the sun/truck are charging... and if the sun/truck are not charging then the WFCO would come back up to 'bulk' and charge the batteries through the BCDC?

- second question is, with live power coming from the WFCO and the TRUCK/SOLAR at the same time (wired together at the DC input of the BCDC), will everything play nice, or will something burn up or catch on fire?

- third question is: Am I missing something and this is either not an issue, or is there a better way to solve it?

Thanks!
Bob
  • NRALIFR's avatar
    NRALIFR
    Explorer
    Jan 09, 2019
    While the Redarc install instructions don’t directly address the multiple charging devices that could exist in an RV, they do state that the Redarc input wire should be connected to an appropriately sized wire going to the truck’s battery (not the alternator), and the output should be connected directly to the auxiliary battery it will be charging, and as close as possible to it. That’s how I installed mine.

    Also, the OP’s Redarc model and the 25 amp version I’m using have a built-in MPPT solar controller and a separate input wire for the panels.

    Sorry for being redundant 2112, we were posting at the same time :)

    “What’s not to like?”

    Just the price! :B

    :):)
  • 191124x7's avatar
    191124x7
    Explorer
    Jan 09, 2019
    The REDARC has an integrated MPPT. So it’s really just 2 inputs to the system. My current plan is for both to be directly wired to the battery, but I feel like WFCO to REDARC could be potentially more elegant.
  • 191124x7's avatar
    191124x7
    Explorer
    Jan 09, 2019
    NRALIFR wrote:
    While the Redarc install instructions don’t directly address the multiple charging devices that could exist in an RV, they do state that the Redarc input wire should be connected to an appropriately sized wire going to the truck’s battery (not the alternator), and the output should be connected directly to the auxiliary battery it will be charging, and as close as possible to it. That’s how I installed mine.

    Also, the OP’s Redarc model and the 25 amp version I’m using have a built-in MPPT solar controller and a separate input wire for the panels.

    :):)


    I emailed REDARC, and I specifically asked them about WFCO playing with the REDARC. Here is their answer, “Charging from one source at a time is always the most ideal circumstance, as two charging sources at once can cause early float stages, and an incomplete charge.”

    I’m going to ask them the WFCO to REDARC question now.
  • NRALIFR's avatar
    NRALIFR
    Explorer
    Jan 09, 2019
    The first problem I see to connecting the WFCO’s output to the Redarc ‘s input is you will be limiting your maximum charge rate to 40 amps. Can’t your four AGM’s handle more than that?

    Bob, I honestly think the scenario of having the solar controller in the Redarc and the charger in the WFCO trying to charge the batteries at the same time isn’t the problem you may think it is. Your panels can’t force 40 amps into the batteries if they aren’t at a state of charge that will accept it. So what if they both sit there in float for a few hours? Eventually the sun is going to go down, and the panels will stop producing power. Then the WFCO charger will go into bulk if the batteries need it. Except, you’re on shore power, so why would the batteries need any more than float anyway?

    :):)
  • 191124x7's avatar
    191124x7
    Explorer
    Jan 09, 2019
    NRALIFR wrote:
    The first problem I see to connecting the WFCO’s output to the Redarc ‘s input is you will be limiting your maximum charge rate to 40 amps. Can’t your four AGM’s handle more than that?

    Bob, I honestly think the scenario of having the solar controller in the Redarc and the charger in the WFCO trying to charge the batteries at the same time isn’t the problem you may think it is. Your panels can’t force 40 amps into the batteries if they aren’t at a state of charge that will accept it. So what if they both sit there in float for a few hours? Eventually the sun is going to go down, and the panels will stop producing power. Then the WFCO charger will go into bulk if the batteries need it. Except, you’re on shore power, so why would the batteries need any more than float anyway?

    :):)


    Actually, that’s pretty hard to argue. I think I’m going to leave it be. I will post the answer I received from REDARC just for science. It will probably be tonight, as it is 130 in the morning there now. Thanks!
  • 2112's avatar
    2112
    Explorer II
    Jan 09, 2019
    "Charging from one source at a time is always the most ideal circumstance, as two charging sources at once can cause early float stages, and an incomplete charge.”
    I can see this happening if both chargers are smart enough. They may trick each other into thinking the battery is charged.

    However, I believe the WFCO is timed. As I understand it, it will stay in absorption mode for a day or so, then go to float. I have never seen my WFCO put out anything other than 13.6V to 13.8V. And it's powered on 24/7.
  • time2roll's avatar
    time2roll
    Nomad
    Jan 09, 2019
    NRALIFR wrote:
    Also, the OP’s Redarc model and the 25 amp version I’m using have a built-in MPPT solar controller and a separate input wire for the panels.
    I like the idea of a 25 amp model so I could use the existing 12v connection from the truck that feeds the trailer. Would limit the solar however.
  • NRALIFR's avatar
    NRALIFR
    Explorer
    Jan 09, 2019
    I went with the 25 amp model simply because I’m a tightwad. I had a hard enough time swallowing the $370 price for it, and the 40 amp model is about $60 more.

    Redarc’s install instructions recommend a minimum of 6 AWG wire for distances of 16-30 ft. I used 4 gauge on mine, the cost difference was negligible and if you use fine strand welding cable it’s very easy to work with.

    On a crew cab pickup, you might be surprised how quickly you can use up 25’ of wire when you start running it from the truck batteries, through an appropriate isolator and fuse or CB, along the frame rail making sure you are avoiding/mitigating heat, pinching, chaffing, etc, to a connector in the very front of the bed, through the camper umbilical, to wherever you are going to mount the Redarc. If you ran the wires to the rear of the bed, you’d be well over 30 ft.

    I installed the Redarc after experiencing how pi$$poor these new trucks auxiliary battery charging capabilities are, despite having a “super heavy duty alternator”. I was running my fridge from an inverter while driving, and the truck just wasn’t keeping up with the draw from the fridge. I was arriving at my destination in the evening with the camper battery at 75-80%. The Redarc solved that problem, but what I’ve also learned is that the DC mode on my fridge now works well enough that I don’t need to run it from the inverter. The Redarc is keeping the camper battery voltage much higher than before, so the 12 volt heater in the fridge works noticeably better. The 25 amp Redarc has plenty of capacity available to run the fridge even at its lowest temperature setting (100% duty cycle) and still charge the camper battery. I now arrive at camp with ice cold beer, frozen hard ice cream, and a camper battery that is about as close to fully charged as a battery in use can be.

    That’s what I call a good return on investment :B

    :):)
  • 191124x7's avatar
    191124x7
    Explorer
    Jan 09, 2019
    I’m not sure I understand REDARC’s answer; but the gist of it is, hooking the WFCO to the REDARC won’t work. So I’m going to let it be for sure.

    Here is their answer:

    “If you connect the WFCO only to the input of the BCDC1240D, this will not work.
    The BCDC1240D is looking for battery voltage, and the WFCO is looking for a voltage in order to supply power – the BCDC1240D does not have battery voltage on the input without a battery connected.
    If you had both the truck and the WFCO on the input, the BCDC1240D would turn on under normal voltage thresholds once the truck reached 13.2V, and start drawing the current required to charge the auxiliary battery.
    If the WFCO could keep up with the current requirements to charge the truck battery, and sustain amperage required to charge the auxiliary battery, this would work just fine.”
  • MoparBob's avatar
    MoparBob
    Explorer
    Apr 11, 2019
    191124x7 wrote:
    I’m not sure I understand REDARC’s answer; but the gist of it is, hooking the WFCO to the REDARC won’t work. So I’m going to let it be for sure.

    Here is their answer:

    “If you connect the WFCO only to the input of the BCDC1240D, this will not work.
    The BCDC1240D is looking for battery voltage, and the WFCO is looking for a voltage in order to supply power – the BCDC1240D does not have battery voltage on the input without a battery connected.
    If you had both the truck and the WFCO on the input, the BCDC1240D would turn on under normal voltage thresholds once the truck reached 13.2V, and start drawing the current required to charge the auxiliary battery.
    If the WFCO could keep up with the current requirements to charge the truck battery, and sustain amperage required to charge the auxiliary battery, this would work just fine.”


    Did you get the REDARC wired up and if so, how is it working for you?

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