Weatherizing (sort of) a battery for portable QRP ops

A 7.2 amp-hour battery gets a new home for portable operations, courtesy of a 1.6 liter Really Useful Box -- yep, that's its trade name. The handles clip onto the ends of the lid to secure it to the box

With the weather warming up, it’s time to take the radios to the field — and the battery(ies) to power them.

Last summer, I put together a tight little field battery pack for my Elecraft KX1, housed in a small Really Useful Box from Staples. With the addition of an FT-817ND QRP radio to my shack, I needed a battery with a  little more oomph. So, during Lobstercon last summer, I picked up (for a song) a small UPC at the event’s mini swap meet and copped its 7.2 amp-hour battery.

But with a pair of bare terminals, the battery is not the kind of thing you want rattling around loose in a day pack. And if it sits out on a table when the rain comes, well, that can lead to major unpleasantness as well. Which led me back to the Really Useful Box collection at Staples.

The battery fit into a 1.6 liter box snuggly end to end, and with room to spare front to back. I used the box to carry it to several outings last year. But what about using it to run more than one black box — maybe some accessories to go with the QRP radio, such as an outboard keyer or my NEScaf audio filter. And just maybe, a place to connect the A & A Engineering battery charger kit I’m wrapping up this week. Or a solar panel/charger at some point.

And so, a new battery case was born, but not without a learning curve.

We’ll take a little journey through the project via photos, with a side trip or two for self-depreciating editorial comments.

This is what I started with -- the box and a battery. Note the plastic-covered spade clips, which I picked up at Radio Shack while foraging for other stuff. The clips are there to protect the terminals and will become part of the project later.

For multiple connections, I picked up an Anderson Power Pole panel mount that can take four sets of connectors. Note that the connectors are arranged so that it's impossible to misconnect them in the dark and blow a radio.

With the connectors set into the panel mount, it was time to wire the connectors, starting with the contact-crimping exercise. Always fun with small pieces of wire!

In went the positive wiring...

...then came the negative wiring.

And now comes the first self-depreciating editorial comment:

I picked up the Power Pole parts at a hamfest in Framingham, Mass., in early April. I’ve assembled several Power Pole connectors for various projects, but this is the first time I tried to build an array of Power Poles. All went well, and my trusty digital multimeter showed no shorts or misconnections. But, really, it would have been a lot faster buying one of these pre-assembled from the guy at the hamfest selling the Power Pole products. Note to self: Sometimes, do-it-yourself bragging rights are over-rated.

The panel mount is finished, with spade connectors in place and a home for a fuse -- probably on the order of 5 amps or so.

Now for mounting. I scored one side of the case for the 1" x 1-7/8" hole the panel-mounted array needs. Those of you who are astute will recall that the box in the photo at the top of this post is clear, not blue...

…and therein lies self-depreciating editorial comment No. 2:

These boxes are a bear to cut. Easy to scratch, but cut? Razor-sharp pocket knife (the safest kind)? Multiple passes along the scored line only slightly deepened the grooves each time. Same with a box knife plus fresh blade. In the end, I finally broke through along one section of line, but not before cracking the adjacent plastic. So, it was off to Staples for another box, and they were out of blue. Purple isn’t my color, so I opted for clear.

And here’s what happened next.

After scoring the dimensions of the opening with an awl on one side of the second box, I drilled a hole in the center of the section to be removed. Then I attacked it with a nibbling tool I bought at least 30 years ago but until now had never opened. Glad I kept it!

The nibbling tool does a nice job, although it also mars the plastic near the cuts. Oh well. And no, I wasn't thinking of the first letter of a kind of bomb as I was nibbling and contemplating the time spent on a do-over.

In the end, the nibbling tool indeed did a nice job of cutting out the requisite hole.

The Power Pole assembly snaps snugly into the opening...

...and with battery in place and connections complete, there's still enough room left in the box to store a small Watts Up meter for tracking power use when I'm using the battery. Yeah, it's there, up on its end at the back.

That’s about it. For true weather-proofness (now there’s a word!), I’d still have to cover the box with a plastic bag. (“Is it really that ugly?” he asked.) The Power Pole connectors are exposed to the elements. But at least the box buys an extra couple of minutes to hunt down that bag before the skies really open!

And, of course, only after finishing the project did I learn that Anderson makes some truly waterproof connector assemblies. Oh well, maybe at the next hamfest…

13 Responses to “Weatherizing (sort of) a battery for portable QRP ops”

  1. Dave Cornell, Lynnwood, WA Says:

    Thanks for the continuing photo-documentation of your projects. Having put together about eight PowerPole Anderson connector pairs for my battery pack and 12-volt systems in the house last year, I understand the time and effort it takes to assemble those pieces. It’s easier said than done. I’m still working on my vertical antenna project , with flagpole now working on 30-20-17-15-12-10m. I’d prefer to have 40m too, even at sacrafice of 30m, so that’s the final part of the work. More later.

  2. Great project. Just a suggestion for the next time (?!) you need to cut holes in this kinda plastic. Track down some “hook” blades for your box cutter, the king that are used for cutting vynal flooring, it’ll make the job a whole lot easier and safer. Covering the “foot” of the nobbler with painters tape will help prevent the marring of the plastic around the hole being cut. Nice job though, now I know where to go for a waterproof battery housing for my own TTF expiditions.
    God Bless and above all….Enjoy!

  3. Nice Pete!

  4. Thanks, Pete. Some good ideas here !
    As always, photos are a big plus.
    Dick, N4UN

  5. Just the inverse of Wayne’s idea about painter’s tape on the foot of the nibbler would be tape on the plastic – might help with layout lines, too. And I wish I’d remembered to go to that flea market in Framingham. I wonder what I was doing that day???

    John KK1X

    • Oh, probably something important.😉 I have to say that when I arrived, about an hour or two after it opened, I was a bit underwhelmed. My reference point, unfortunately, is NearFest. I suspect these smaller gigs have an ebb and flow to them from one year to the next. It will be fun to see what’s available next year.

  6. Phil Says:

    Thanks Pete. Always look forward to your projects / posts. Hey, now I know what I’m going to do with that small UPC sitting unused in my basement….
    Phil, N1DN

  7. […] orange Jackite pole as a center support for the light-weight doublet. I hooked my FT-817ND up to my newly tricked-out battery, and with a ZM-2 antenna tuner to run  interference, I fed some RF into the […]

  8. […] orange Jackite pole as a center support for the light-weight doublet. I hooked my FT-817ND up to my newly tricked-out battery, and with a ZM-2 antenna tuner to run  interference, I fed some RF into the […]

  9. […] weatherized (sort of) a 7.2 amp-hour battery two weeks ago for use with my QRP radio in the field. But there was a minor problem. The battery […]

  10. […] weatherized (sort of) a 7.2 amp-hour battery two weeks ago for use with my QRP radio in the field. But there was a minor problem. The battery […]

  11. […] I said to myself: “Self,” says I, “Why not set it on top of the battery case you put together for the 7.2 amp-hour battery that powers this get-away […]

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