Power Center Box for Field Ops

While I was crawling under the table on Field Day hooking up AC and DC gear it occurred to me that I could improve things with a Power Center Box. So I spent a little time thinking about this and thought that others might be interested and have suggestions.

Also visit the companion RadioBox page.

Baseline Gear:

• AC power strip with several outlets
• RV power supply to provide 12V from 120V and charge the battery as well as operate the loads when AC is available
• 12V AGM battery (in my case 49AH, sized to be compatible with safety regulations at AmTech day (50AH limit))
• DC power strip with Anderson Powerpoles
• Fuses
• Battery disconnect switch

Upgrades:

• AC metering - voltage, frequency, current, power
• DC metering - voltage, current, power, integrated charge/discharge
• GFCI (ground fault interruptor) to protect against AC hazards
• Make the AC inlet cord be unpluggable
• Solar Panel input jack, Solar Charge Controller mounted in the box
• USB charging jacks for charging things that have USB charging ability
• Cigarette lighter 12V jacks
• Small AC Inverter to make AC for charging laptop, cellphone, etc. (when AC input is not available, or for UPS type AC power)
• Voltage Booster for rigs that work poorly on 12V and need to see 14V or so
• High current jack for 12V linear
• Other standardized 12V connector(s)
• Extra battery jack for external additional batteries
• Possibly larger or more batteries, though the weight is getting to be a problem. Even a 49AH AGM is already 35 pounds and there are a number of other things adding weight to this package. Try to stay under 50-60 pounds?
• Could make the battery be separate from the box...
• Lithium Iron batteries would be interesting but the power supply/charger would be problematic, charging LiFePO4 batteries in standby use is not as easy as AGM.
• LED lighting? Not the best location for lights but could have some floor lighting LEDs.
• Low battery alarm and/or cutoff (low voltage disconnect) protects the batteries

Case/Box:

There are many possibilities here, at various prices. The best I have found
so far is the Pelican 1440 vertical roller case. While not the cheapest
alternative this box and gear will in my case weigh about 60 pounds
(estimated) so it needs to be sturdy and have a good handle. Having rollers
will be useful in some situations such as AmTech day where surfaces are
suitable for wheels. The 1440 is available in a few colors including Orange
which seems appropriate for power. I found them on the web from Leisure Pro
without foam for about $130. Various other boxes are available at lower
prices from other vendors. The Case Club is another place to look on the
web. Ebay and Coast to Coast are other good places. Frys Electronics has
some cases as well. Or build one from wood, plastic or fiberglass.

The AC to 12VDC power supply I have for portable work is a Progressive
Dynamics 9130A. It is designed to provide 30 amps at 13.6 volts to both
operate equipment and charge batteries in an RV. It is a switcher but it has
been quiet RF wise. It has a variable speed fan and weighs only 4 pounds. It
is designed to handle a battery floating across its output which is very
important for this application and provides great convenience and good power
continuity.

Fitting all this stuff in is going to be a challenge. Ultimately the size,
weight and fit is the limiting factor on a practical box. But having
everything wired and ready to go is a real time saver. You just sit this box
under the table, plug in the radio and you are ready to go power-wise. The
generator can be hooked up when convenient and keep things charged up.
Having all the components pre-wired will save a lot of time and avoid
problems - one year I blew a couple of fuses on DC wiring - this would have
been avoided with a pre-wired setup.

7/11/2010 Update

The Pelican 1440 Roller in Orange has arrived. It has a great handle and the Orange is pretty bright. No one will miss this box. Just as a quick trial I set the 49AH AGM battery, the 30A RV supply and the voltage booster in the box. It all fits nicely into about 60% of the space. Great! There will be room for wires, framing, etc. Looking Great so far!!!


PowerBox Light (weight)

I built a lightweight powerbox some time back. It houses four 30AH Lithium Iron electric car cells. It is mounted in a Harbor Freight 11 inch case. This produces 13V with high current capability and the box is lightweight. I don't have the weight as I write this, but it is less than a 17AH Gel or AGM battery and it produces about twice the ampere hours, higher voltage and higher peak current. There is a little room left in the box so I might put a charger in there at some point. This is a great box for quick tabletop operations. I ran my K3 on it for hours at Field Day this year and it worked well.

PowerBox Amplifier Companion

Some years on FD we have used amplifiers. In my case a 12V 500W output amp drawing up to 80A. This requires more than one 49AH battery. One way to handle this is with a second powerbox companion box for the amp:

• Second AGM battery
• Connectors suitable for 100A load (powerpole 175A)
• Fusing
• Disconnect Switch
• Second AC PS
• LARGE CAPACITOR say many Farads

-- AlanB