note: first appeared late 2015

I decided to build this really cool solar rechargeable battery powered Portable Power Box. The Power Box was to provide battery-based power in the event the AC power went out.

So I went back to the basics of a Power Box…supply power to a Radio Go Box solution in that build. As I went through that process it became clear to me that I had two distinct missions for Ham radio operations. Dual mission needs…

One mission was the “emergency preparedness response” and the other was more along the lines of “grid-down” or field-going type of missions. And they have somewhat different operating environments. But either way, my Go Box had to be stand alone. That threw me into coming up with a very small self-contained, stand-alone Go Box. But I wanted this box to be geared towards the “grid-down” and field-going missions.

The Go Box has to be a completely self-contained unit that enables a person to use a mobile Ham radio without external power. I chose the “mobile” aspect to provide for as much transmitting power as reasonable, given the field portability aspect.

The unit will also have a battery in the box to provide power for itself independent of any other power source. Obviously the battery can’t be very large so the ampere hour capacity will be relatively small. But the design will provide the unit with the capability to connect a solar panel for power to run the radio and to recharge the battery whenever there is sufficient current from the solar panels.

Additionally, I am toying with the idea of being able to “daisy chain” Power Boxes together to increase ampere hours capacity (operational time). 

NOTE#1 : For solar recharging the Go Box I currently have GoalZero Boulder30 solar panels with a GoalZero Guardian charge controllers. However, I am researching and will soon begin field testing a dual 30w (60w total) system that is showing a lot of promise and has a lot of potential. I am also trying out a couple of other charger controllers to improve overall charging efficiency.

NOTE #2 : I also am looking into low voltage disconnect units (LVD) to protect the battery from over-discharging. All of this is going to take some pretty tricky engineering to get it right. At any point if you are seeing something that isn’t making sense, or is a potential problem, please say to me something right then and there.

So back to the Go Box project…

I have outlined some of the basics and the mission for the unit. Now let me start outlining the components:

Container. I have decided on the .50cal ammo can as the container for the Go Box. There are a whole list of reasons but here are few primary ones –

• They are extremely sturdy.
• They are water and airtight.
• They are a very convenient size.
• They are also my choice of container for Portable Power Boxes.
• They have a nice, sturdy, collapsible carrying handle.
• I have several in my shed that need using.

Once I decided on the container I struggled on keeping the integrity of the box in-tact. In other words, do I drill any holes through the box for mounting purposes? I worked at it for a couple of hours laying it out. The only really feasible method to mount much of the guts was to drill holes through the box, thus, breaking the container’s integrity. But I think it is worth it and won’t significantly reduce the container’s overall usability for this project in the intended environment.

Next I had to decide exactly what would go into the box. That may sound kind of silly but I wanted to keep the component list to a minimum. I wanted to keep costs low, reduce the amount of heat generated, keep it as lightweight as possible and I didn’t want it all jammed up. So here is the component list I came up with:

Radio. Yaesu FT-8900R. That is the best all-round radio for emergency work. It has the two main freq bands 70cm and 2m. Plus it has a small section of HF band as well. The radio is amazingly rugged and reliable. And the bonus was…it was the perfect width for the width of the box.

Optionally, I can use the Yaesu FT-8800R as well. It has the same case dimension as the Yeasu FT-8900R. So yes, that means I could turn this into a portable repeater as well.

Battery. Duracell Deep Cycle SLA, 14Ah. The choice of battery was due more to available space than anything else. It was simply a matter of what was the highest ampere hour battery I could get into the box and not interfere with the other components’ installation.

Technical Specs –

• Item Number: WKDC12-14F2
• Brand: Duracell Ultra
• Voltage: 12
• Lead Acid Type: Deep Cycle
• Capacity: 14AH
• Chemistry: Lead Acid
• Lead Acid Design: AGM
• Terminal Type: F2, T2, Faston .250
• Weight: 9.2 lbs

Volt Meter. I have started obsessing over the life span of AGM batteries. AGM batteries are expensive, but they are also really good for Ham radio operations. But they are expensive. Over discharging AGM batteries really reduces their life span. Did I mention that AGM batteries are expensive? Monitoring a volt meter and ensuring that you don’t drop below the safe SOC level keeps your battery in good shape. To track the battery voltage condition I went with the Powerwerx Panel Mount Digital Volt Meter. It has a nice blue display and I’ve used them before. Again, available through Powerwerx.com Nice little high-quality units. But this volt meter will be mounted inside of the box not mounted on the exterior.

Flexibility. By itself this is not a single component but rather a design methodology. I want to ensure that the parts in all my radio and power boxes are interchangeable. That means using Anderson Powerpoles for connections. And I also threw in a 4-way connector to eliminate splicing of wire.

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