No announcement yet.

Review/Guidance on DC Powering Plan for CarPC/Router/IP Camera etc.

  • Filter
  • Time
  • Show
Clear All
new posts

  • Review/Guidance on DC Powering Plan for CarPC/Router/IP Camera etc.

    Update for 14-Oct-2006:

    I connectorized all the underhood battery cables and wired in the Isolator and Circuit Breaker. Ready to move inside the cab of the truck now. I'll be relocating the PSU for the CarC and all of the power wires and connections to underneath the back seat, along with a new fuse block, AGM battery, circuit breaker, relays etc.

    One new picture below and more here.

    Update for 08-Oct-2006:

    My parts have begun to arrive for repowering all of my CarPC gear. Yesterday, I determined a mounting location for the SurePower 1620 Multiple Battery Isolator and the Phoenix Gold 100 Amp Circuit Breaker and I fabricated and painted a mounting bracket for the isolator.

    Today, I mounted the isolator, frabricated a bracket for and mounted the circuit breaker. Pictures below.

    Much wiring to do next. Waiting on the 4 gauge terminals, solder slugs, heat shrink tubing, high-temp split loom, Blue Sea fuse block etc.

    I am looking for a review and some guidance on my DC Powering Plan. I am no expert at this – nor am I a graphic artist or circuit designer (i.e. my design below) – please hold the serious pot shots. If you have a few minutes and some great experience, perhaps you could impart some of that wisdom to me.

    2005 Dodge RAM 3500 with Cummins Turbo Diesel (I pull an RV with it)
    Truck has 2 large 12 volt batteries wired in parallel for starting that diesel and a 130 amp alternator

    Presently, in the truck, I am running: Xenarc MP-SC8p Mobile PC, CarNetix CNX-P1900 PSU, Xenarc 7” (TS) LCD, IO Gear (powered) USB Hub (connected to hub: Optical Mouse, BT Transceiver, Keyboard Receiver, Garmin 18 GPS Receiver, Touch Screen Controller), Junxion Box Mobile Router (built-in WAP) with Sierra Wireless 580 AirCard and an Axis 2100 IP Camera.

    Current method of power:
    A 30 amp fused 4 gauge power cable wired directly to one of the stock batteries through the firewall into the cab and into a power distribution block. All items are wired to the block and are individually fused at the block. Common grounding is also done at the block, then 4 gauge cable to chassis for ground. Switched ignition 12 VDC is also wired to CarNetix PSU. Startup/Shutdown Controller in PSU is configured to power down PC and USB Hub (and USB devices) 15 minutes after ignition is switched off. Direct wired DC power remains on to PSU (parasitic load only), Router/WAP/AirCard and IP Camera – 24/7.

    Current Problem (not even a pun!):
    Because I choose to power the Router (for HotSpot capability) and the IP Camera - 24/7, I have a small but continuous load being put on the truck batteries (2-3 amps perhaps). All was well all summer until one recent Monday morning. Went out to start the truck and ‘click-click-click’. Batteries were well under 10 VDC. Had to put a long charge on them to bring them back far enough to turn the starter.

    The Plan:
    I never want to be in a situation where my truck will not start due to low battery voltage. As such, I want to build a separate DC Power System for my stuff. My idea/plan as drawn below is to add a 3rd battery to the system. I would isolate it from the truck batteries via a SurePower #1602 160 amp isolator. The 3rd battery would be fused at the isolator and would have a circuit breaker at the input to the battery. It would get recharged from the truck alternator. All my stuff would be powered from the 3rd battery.

    Questions for those more expert than I:
    1. Overall - does adding an isolated 3rd battery to power my stuff - sound viable?
    2. Is fusing the 3rd battery feed at the Isolator output and then having a circuit breaker at the input of the battery, a sound way of protecting the feed from accidental shorts? I used the fuse in the design in order to be able to do a hard disconnect in the cab without having a separate disconnect switch or having to pull a fuse.
    3. My design shows a SPDT NO relay after the 3rd battery and activated by a SPST toggle switch in the cab within easy reach of the driver. This allows me to "easily" cut power to all my gear form the dash without having to unload camping gear from the seats to get to the breaker. Does this sound viable? I have no hand-on experience with relays but my sense is that I would want to use NO instead of NC so that I am applying power to the relay coil only when I want power to be on to my gear. When I want the gear power to be off, I don't want power to be applied to the relay could to hold it open. Is my head on straight on this? Will it hurt a relay coil to be energized for long periods?
    4. Should my 130 amp alternator be able to charge 3 batteries? Hate to have to change it out.
    5. The 3rd battery is uses an Absorbed Glass Mat (AGM) chemistry. Wonder if adding AGM to the truck with lead-acid, although isolated would cause any issues. SurePower felt it would be fine if the alternator provided the charge voltage required for AGM. So far as I know, AGM requires what a lead-acid battery would in terms of charge voltage. Am I wrong on this?

    If you can help me with one or more of my questions above, please reference the question number in your reply.


    Link to: CarPC
    Link to: Avalon Project
    Link to: RAM Cam
    Link to: Ford F550
    Link coming: Prius

  • #2
    It sounds like it would work no problem. My question is why dont you just buy one of those battery guards the will kill power to anythign but the ignition if voltage drops below a certain point, generally around 10.5 volts?


    • #3
      Thanks for the reply. The reason is that I run the Router 24/7 as a HotSpot. We use it extensively when we travel with our RV. We're in and around the trailer and the truck just sits there for several days providing WiFi Internet access. So I want to continue that capabiity with no effect on the truck starting batts.

      Link to: CarPC
      Link to: Avalon Project
      Link to: RAM Cam
      Link to: Ford F550
      Link coming: Prius