Man Portable Off-grid Power for Amateur Radio Part 4

Hello Operators
Welcome to part 4 of the Man Portable off-grid power for amateur radio series. In this episode we’ll discuss power distribution, connections and protection using a bespoke or commercial powerpole distribution board.

Let’s take a moment to reflect on the articles previously published in the series.

As Radio operators, many of us already know what power distribution means. I like to describe it as “taking DC in from a power source, to divide and distribute amongst fused output ports”. Simple isn’t it? Well the power distribution box also has another job. It acts as the breakout box for my battery pack. 

In the context of Man portable power for amateur radio, my DC distribution board relies on 30A Anderson powerpole connections, with fused inputs and outputs. It also provides a single USB output, and voltage display, giving me some idea of the state of my 10Ah 4S1P lithium iron phosphate battery pack.

Although I could have built this myself, I found a nice kit from a website in USA.  the only problem with that kit, and the reason I’m not going to give it a plug in this blog post, is the maker of this kit either doesn’t understand or doesn’t care about the field operator. I asked on more than one occasion about a fitted top cover for the kit, but he wasn’t having any of it saying “It really doesn’t need one”. To be fair this is an excellent kit! I have two of these that I bought and paid for, then built with my own hands. Not having a top cover  isn’t really a problem for the one I have in the shack. But when I’m out in the field  a top cover is essential  to preventing mishaps. I would even be happy with a 3D build file, to have the top cover printed myself, but again the maker wasn’t having it. Okay! That’s why I’m not plugging his kit. Instead, I’ll plug the one I should have purchased in the first place. It comes from a maker who understands very well the needs of the field radio operator. That maker is  SOTABeams.

SOTABeams has two versions of their distribution units, both of which are available with enclosure and fitted top cover. Here are some screenshots from their website.

Benefits of the power distribution
Whether your building or whether you’re buying, the power distribution box will simplify connectivity between your peripherals, and your battery pack. If you also use fused outputs on your distribution box, those fuses not only protect your peripherals, they also protect your solar charge controller and Battery from damage during any mishaps.

In this image you can see the relationship between the battery, solar charge controller, and the power distribution box. 

  • The battery connects to the BMS (battery management system).
  • Battery management system connects to the battery plus and minus ports, and to the battery port on the solar charge controller.
  • The Load output on the solar charge controller connects to the power distribution unit input.
  • Your radio laptop tablet or whatever devices you’re planning to connect to your battery pack are connected to the fused outputs on the power distribution unit.

Power distribution and solar panels

There’s also another way we can use the power distribution units. We could also use them to connect similar types of solar panels in parallel to our solar charge controller. This adds a bit of modularity to our kits, during deployment.

Power sharing
Another good reason to use a fused power distribution board is DC power sharing in the field. Let’s assume another operator needs to slave off your off-grid power system. Perhaps that operator has some sketchy cables. Allowing him to plug into your power distribution box, on his own fused output Channel, protects the rest of your system from any mishaps caused by poor cables. This means you can share a Channel or two from your power distribution box, to an operator in the field, without the risk of his incorrectly implemented system damaging the rest of yours. In the worst case scenario, we simply replace the fuse for his/her channel on the distribution box. This takes all the risk out of being neighborly 👍.

Other commercial distribution boxes
Finally, there are other powerpole distribution boxes on the market.  Still you’ll need to decide for yourself whether you’re going to build a kit, buy a ready commercial unit, or design and build the kit yourself. Whichever way you go, and however you decide, make sure your powerpole distribution box is based on your own requirements.

de oh8stn 

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