Power
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Power Box v3 - February 24, 2020
About two years ago I built a new version of my Power Box, which turned out pretty well and performed great. I liked the smaller form factor and versatility of it, however, the build-out was a little cludgy and didn’t make the best use of the equipment (having to open the lid to see the power meter was less than ideal).
This new build makes use of the large Tac-comm carrier I previously used for the HF module in my Go Kit. In the year since that version of the build I decided to go a different route regarding this part of my kit, so I had the carrier available for reuse. This build is essentially a re-casing of the same equipment I had in the previous power box; the only alteration is the circuit breaker. I replaced the generic, no-name unit I had been using with a genuine Bussman RV style circuit breaker. I also changed the circuit breaker to one with a 35 amp trip instead of 40 amp. This was done because all of the West Mountain gear I am using for this build (PWRcheck & Epic PWRgate) are rated for 40 amps and I wanted the breaker to trip before potentially damaging any of this expensive equipment. I won’t be using much over 20 amps at any given time, so this shouldn’t restrict my operation in any way.
As luck would have it, all of my power box devices fit perfectly inside the larger size Tac-comm carrier. There is plenty of room to wire everything and this layout also provides the massive benefit of mounting the circuit breaker and power meter in the front of the case. This makes turning the unit on and off and checking my state of charge and power consumption super convenient. The front mounting plate is made of a sheet of ABS plastic mounted to a section of aluminum angle that is bolted to the carrier. The PWRgate is mounted to the carrier using velcro strips which hold securely while also allowing for easy removal. I had a few different ideas for how to mount the battery, but I ended up using 12 squares of super heavy duty velcro. Each square can hold 2 lbs and the battery weighs under 11 lbs, so it shouldn’t be going anywhere. I also added some padded strips to the top half of the carrier to keep the battery from shifting.
The end result of all this is a much more convenient and versatile power box. The weight increased slightly to 17.25 lbs, but it’s more compact overall and the build quality and looks are much improved and due to the slits in the carrier, the LED indicators on the PWRGate are still visible so there really isn’t any loss in functionality. It’s also super easy to work on, just remove 4 screws and the top cover comes off for access. I think I might have finally found the ideal power box configuration.
Power Box v2 - March 28, 2018
I only built the previous version of this box a few months ago, but I learned a lot from building that case. The main thing I learned is that rack cases aren’t necessarily the best option for a power case. Rack cases are great for radios because they provide ready access to the front and rear of radios and other gear. For a power box the extra lids, bulk, and weight of a rack case don’t provide enough benefit to overcome the drawbacks. I also quickly realized that I really don’t need an inverter. I found a very compact and high performing 12V adapter for my laptop that makes the inverter unnecessary. This all combined with the awkward power wiring and inadequate power monitoring of my previous case pushed me to rethink my power box.
Case
I wanted a case that would make the most of the small size of my 40 Ah lithium-iron-phosphate battery. The one I ended up using is only $15 at Lowes. The battery sits in the case and is kept from shifting by stacks of cardboard cut and glued to fit the taper of the case. This works well to keep the battery stable while allowing for easy removal when needed. The power circuit is wired with 10 AWG wire and the battery is fused using 40 Amp ATC fuses.
Power System
From the battery the power flows through a West Mountain Radio PWRcheck. This device is an inline power monitor that measures voltage, amperage, power, and amp hours. It can also log power usage and provide a battery gauge when the battery’s amp hour rating is input via the unit’s control software and USB connection. The PWRcheck can also be setup to alarm at low and high voltage along with other features. The PWRcheck then feeds a WMR Epic PWRgate. I used this device in the previous build and it works well as a battery charger in addition to channeling power from solar, battery, or power supply inputs to the output. Both the PWRcheck and PWRgate are mounted using heavy duty velcro, the PWRcheck to the top of the battery and the PWRgate to the side of the case. This allows for easy removal, while also securely holding them in place. The PWRgate’s solar and power supply inputs and its power output are wired to powerpoles mounted to the outside of the box. All wiring was done using 10 AWG wire except the solar which is 12 AWG since it doesn’t carry as much current. I also used blue & gray powerpoles for the solar connections to differentiate them from the others for easy identification. The final piece of the power system is a WMR RIGrunner 4005 mounted to the outside of the case using heavy duty velcro. This allows flexibility to either provide power distribution from the case itself or move the RIGrunner to another location and provide power from there via an extension cable from the power box. All of the power system devices are rated for 40 Amps of continuous current which is more than enough for my purposes.
Operation
I really wanted to keep this build super simple and flexible while maintaining a lot of functionality and I feel good about how it turned out. The case itself is just the battery, power monitoring and a charging/distribution system. Everything is modular, light and there aren’t any unnecessary devices or wiring. This new version of the power box weighs in at only 16.5 lbs, a little over half the weight of the previous build. My previous go kit total weight was about 70 lbs (radios + power) and the new arrangement totals about 69 lbs. This doesn’t seem like much of an improvement, however, since I rarely need both radio cases I end up saving quite a bit of weight for real world applications. For example, a Field Day or QSO party deployment (HF + power) with my new cases totals about 46 lbs, over 20 lbs lighter than my previous iteration and over 50 lbs lighter than if I used my lead acid battery. I especially like how much less bulky this version of the power box is and the ease of portability that this provides.
Update (June 2018)
After using my new power box for a little while it became apparent that it would be a good idea to have a more convenient way to turn off the power, and therefore minimize any discharge from the battery, than simply unplugging the main powerpole connection. To this end I decided to remove the fuses and in their place put a 40 A circuit breaker. This breaker is bolted to the outside of the case, making it very convenient to access compared to the fuses. This change also necessitated rerouting some of the wiring, but I think it ended up better arranged than before. I used the power box in this configuration for Field Day with my solar panel and everything worked perfectly.
Power Box - November 19, 2017
In the months since completing my revised go kit earlier this year, I have been considering building an improved version of my battery box. I wanted to use the same style of rack case that I used for my go kit and at the same time add a lot of versatility and functionality compared to what my basic battery box offered.
Goals
Reduced Weight
12V Power Output
12V Charging, Switching and Distribution in the Box
120V Power Output
Battery Voltage & Current Monitoring
Solar Compatible
Battery
Reducing weight meant moving away from the lead acid battery that I used previously. These work fine and are not overly expensive, but they have a lot of limitations. My battery box used a deep cycle battery that weighs about 55 pounds. This new build uses a Bioenno 40Ah lithium-iron-phosphate battery that weighs about 10 pounds. It is also significantly smaller and can supply power for a longer period than my old battery. These batteries are not inexpensive ($360), however, they should last through significantly more charge-discharge cycles than a lead acid battery and when combined with the weight and space savings these benefits justify the price.
PWRgate
To handle the battery charging, power switching, and solar power requirements I used the West Mountain Radio Epic PWRgate. This device is a major step in evolution compared to other power gate products in the past. Older units could automatically switch power between a battery and power supply in addition to trickle charging the battery when the power supply was on, but they were only compatible with lead acid batteries. The Epic PWRgate supports multiple battery chemistries and charge rates, making it much more versatile (you select the battery chemistry and charge rate by removing the cover and setting two jumpers to the appropriate values). It is also much more efficient with a reduced voltage drop and no large heatsink. It can take inputs from a power supply, battery, and solar panels while it simultaneously outputs power. Depending on the state of each it can charge the battery from the solar panel or power supply, or direct battery power to the output if the power supply is unavailable. To complete the DC output power distribution system I used the 5 port West Mountain Radio Rigrunner from my old battery box.
Inverter
While not always required, I wanted to have the option to power or charge devices that use 120V. To accomplish this I added a Samlex 300W Pure Sine Wave Inverter to the system. While this is a fairly low wattage for an inverter, the intent of this is to power devices such as laptops, monitors, HT battery chargers, etc. that don’t require a lot of current. I went with a pure sine wave model since they produce much cleaner power, which should help reduce RF noise as well as work better with whatever electronics I am using.
Power Monitoring
For battery voltage and current monitoring I used a standard 1.125″ digital DC Voltage Meter and a Blue Sea Systems Shunt Current Meter. This current meter can measure current in both directions which allows me to monitor both the current draw under load as well as the charge current depending on how I am using the system at that moment. I wired the power inputs for both meters through a switch so that when I don’t need to monitor the state of things I can turn off the meters. This is very handy at night when you may not want bright LEDs shining in your face.
Wiring
The DC power wiring consists of an inline Maxi Fuse Holder connected to the battery’s positive terminal. I used a 50A fuse for the main feed and 8AWG wire. This is routed through the current meter shunt and into a 4 circuit Blue Sea Systems ATC Fuse Block. I used 2 of the circuits: a 30A, 10AWG feed goes to the PWRgate and a 2A, 16AWG feed is used for the meters. The battery’s negative terminal was connected directly to a Blue Sea Systems Busbar. The inverter was wired directly to the current meter shunt and the common busbar. I also ran a ground wire from the inverter ground terminal and through the hole in the back panel. This wire was terminated with a green powerpole for easy connection to a ground rod and serves as a safety ground for the AC circuit.
Construction
The case itself is very similar to that used in my go kit, except this box is a 3 unit shallow case instead of a 4 unit. The shelf is the same model used in my go kit. All of the components were mounted to the shelf using 8-32 & 10-32 machine screws. I had to get a little creative to figure out how to secure the battery to the shelf. In the end I used 3 heavy duty jumbo wire ties to cinch the battery to the shelf and 2 nylon spacers secured with 10-32 machine screws to prevent the battery from sliding laterally under the wire ties. So far this arrangement seems very secure.
The front and back panels were made using 11/64″ thick sheets of ABS plastic. The front panel required notching in the bottom corners to allow for the shelf mounting screws as well as ventilation holes for the inverter fan. The back panel features a large cutout for the inverter outlet & switch and serves as the mount for the PWRgate & Rigrunner. I also added section of 1″ aluminum angle to the back panel which adds a lot of rigidity and prevents flexing when power cables are plugged and unplugged. One unforeseen modification involved the rear case lid. Since the PWRgate is mounted in the center of the case, it’s powerpole connections protrude just enough to make contact with the center brace of the lid. I debated moving things around, but in the end I notched the lid brace using my Dremel and a small cutting wheel. Due to the tight packaging, the jumper wire from the PWRgate to the Rigrunner has to be removed when putting on the lid.
Go Kit Integration
Since the PWRgate is now separate from my go kit I had to modify my go kit’s power wiring to accommodate this new arrangement. This involved adding a powerpole distribution block and permanently mounting the power supply output to the case. For full charging and battery backup capability jumper wires have to be run between the power supply in my go kit to the PWRgate and from the Rigrunner to the new distribution block in my go kit. I tried to organize my jumper cables the best I could to keep things as neat as possible and I used very flexible 10AWG wire with silicone insulation to minimize any cable stress and tangling. When stacked, the two units integrate together very well.
Weight
All together the power box weighs just under 31.5 lbs which is pretty good in my opinion. I’ve added both capacity and a huge amount of capability compared to my old battery box and it still only weighs about half as much.
Solar Charging System - September 23, 2017
Field operations using batteries are very common and my battery box is a very convenient source of power. For longer term operations, however, keeping the battery charged is just as important. In order to supplement my battery system I put together a small solar charging system.
Parts
50 Watt, 12V Solar Panel – Renogy
10 Amp PWM Solar Charge Controller – Renogy
1″ Aluminum Angle
The goal here was to have a simple solar system that would be large enough to charge my battery box at a decent rate, while still being small enough to transport easily. I also wanted to keep the costs fairly low.
I went with a 50 watt solar panel since it is fairly compact (around 2 ft square), inexpensive (about $80), and puts out almost 3 amps at peak sun. The charge controller (under $30) prevents the panel from overcharging the battery when the sun is out and blocks the panel from discharging the battery when the sun goes down. The aluminum angle frame holds the parts permanently together (which simplifies field wiring) in addition to holding the panel at a 30 degree angle. A 30 degree panel angle is a good compromise for my latitude and helps maximize the panel’s sun exposure throughout a full day. All together the panel, controller, and frame weigh about 12 lbs.
Operation
I used this setup with my battery box and go kit for Field Day this year and it performed very well. I generally do digital only on Field Day and made over 160 contacts using PSK31 and RTTY with the radio set for 50 watts output. With the sun out, the panel kept up with my power usage and by sunset the battery was essentially fully charged despite me operating for several hours. I continued to operate after sunset and quit around 1AM. I resumed operating mid-morning and the few preceding hours of morning sun had recharged the battery back to near full charge.
As with any battery testing, the current draw is the deciding factor for how long your charge will last. Since Field Day is in many ways a contest I was transmitting quite a bit which increased my current draw compared to more casual operations. Overall I operated around 16 hours and never drained the battery below 12V. If I turned the power down, I could probably operate the entire 24 hours and dropping from 50 to 25 watts would have minimal impact on my ability to make contacts.
Update (June 2018)
Along with upgrading my power box, I also wanted to upgrade my solar charging capability. Since I already had a 50W panel, I decided to buy another of the same size from Renogy and make my own folding 100W panel system. I used basic zinc plated hinges and keep the panels folded using a simple bolt and aluminum plate system. The bolts also provide points to allow the attachment of aluminum legs to keep the panel tilted at a 30 degree angle to pick up maximum sun. I also mounted a comfortable handle to make the panel system easier to carry. The two panels are connected in parallel and then connected to the power box via anderson powerpoles. This allows the panels to charge my 40 Ah lithium iron phosphate battery via the Epic PWRGate inside the power box.
I used this setup during Field Day this year and it worked very well. We had a mix of clouds, sun, and some rain but the panels were capable of keeping up with my HF digital station (running at 50 watts). In full sun these panels will charge the battery with about 6 amps, more than enough to keep up with the radio’s average power usage which is about 3 amps (mostly receiving, transmitting about 25% of the time). This keeps the battery more or less topped off during the day. I didn’t operate all night, but I did put in several hours after the solar panels had stopped producing power. In the morning the panels came to life again and charged the battery back up some even while I was operating. By the time I packed up I still had about 28 Ah left in the battery according to my PWRCheck. Overall I am very happy with my new power box and larger solar panel system.
Update (July 2020)
I made some upgrades to the latches and leg supports for my folding solar panels. Instead of a crude plate & wing nut arrangement to keep the panels folded, I bought some proper latches and screwed them to the panel's aluminum frame using #6 stainless steel sheet metal screws. I also improved the leg supports. Since I had eliminated the mounting bolts for the side legs, I needed a different way for the new supports to attach to the panels. This was solved using 1/2" CPVC pipe with bends at each end using two 90 degree elbows. This allows the pipe to lock in position by pressing against the panel's aluminum channel frame. I added a couple of aluminum tabs to the panel frame as well to keep the pipe from flexing out of position. The legs themselves are detachable for storage and transport, this also allows me to use multiple lengths if I wanted to vary the angle of the panel (one for summer, one for winter). These two simple upgrades make using the panel a lot more convenient and greatly reduce setup time from a few minutes to a few seconds. There are also no small parts to lose.
Battery Box - February 23, 2016
A portable battery system is a very handy item to have for ham radio in general (think field day, special event stations, etc.) and is essential for an EMCOMM kit. I based my battery box around a deep cycle lead acid battery and I ended up choosing a group 27 battery with a reserve capacity of 160 (66.7 Ah). Reserve capacity refers to the number of minutes a fully charged battery is discharged at 25 amps before the voltage drops below 10.5 volts. This figure can be converted to amp-hours by multiplying the reserve capacity by 0.4167. According the Battery School within a BCI group size, the battery with higher ampere-hours (or RC) will tend to have longer lives and weigh more because of thicker plates and more lead. While lead acid batteries are heavy, they are also versatile and can be continuously trickle charged to keep them at full charge until they are needed. A deep cycle battery is appropriate for this application since their power level can be drained very low without damaging the battery, unlike a typical car battery.
For ease of transport and to keep the wiring organized and neat I store my battery in a plastic battery box and hardwired it to a Rigrunner 4005 power distribution block mounted on the box. I went with a small Rigrunner since this system will only be used with a few items at a time (1 or 2 radios, inverter for laptop power, low voltage lighting, etc.). I keep the battery charged using a NOCO Genius G3500 charger which is smart enough to not overcharge the battery and powerful enough to recharge the battery at a decent rate. After years of thinking about it I finally got around to standardizing all of my power connections with Anderson Powerpoles which make 12V power connections very modular and interchangeable.
This is a very useful and simple project that performs well for my purposes. I could easily parallel another battery with this one for increased capacity if the need arises in the future. You could buy a premade battery box with a Rigrunner, but doing it yourself is a lot cheaper.