Prototype – Richard Nuckolls Professional Site

September 5, 2023February 14, 2024

How to Build Your Own Portable Power Station

battery box sitting on a stone in a field — DIY portable power station

I love my portable power stations. I recently saw a 12V LiFePo4 battery on Amazon Vine, along with several other 12V accessories. That triggered an idea for making a brand new battery box myself. I wonder if I can make the power station out of parts I get entirely from Amazon Vine?

I’ll walk through the steps I took in making my own portable power station. Now I’ve got another option for reliable power wherever I go. You can make you own too.

What is a Portable Power Station?

A portable power station is a device that can provide electricity on the go. It is essentially a battery pack that can be charged using solar panels, wall outlets, or car chargers, and then used to power electronic devices like smartphones, laptops, cameras, and even small appliances like mini-fridges or electric grills.

The main advantage of a portable power station over traditional generators is its fuel source. It does not require any fuel or oil to operate and does not produce any harmful emissions. This makes it an ideal choice for outdoor activities like camping and hiking where you want quiet, clean power .

The most important decision when choosing a portable power station is how much power (wattage) is available. A laptop and a coffee pot take only a little power. A blanket or a kettle takes more. If you want to run a refrigerator or a space heater all day you need a much bigger system. Luckily UL listed electrical appliances list their wattage use.

Uses of a Power Station

Camping

I use my Jackery 500 every camping trip. It powers LED lights, charges my phone, my camera batteries, headlamp, and rechargeable flashlights.

On my first trip this summer, I used it to run a mini-fridge, which I got on Vine. The mini-fridge takes a lot of power; I ended up using the Jackery one day, my Bluetti EB3A the second day, and recharging both from the truck alternator. But it kept the meat and sodas cold!

battery box powering electric kettle — Boiling water with Joulle kettle and Jackery

Cooking at the campsite has never been easier. I have a 5 cup Mr Coffee coffee pot for coffee. It also makes good soup and heats hot dogs. I have a Joulle 500W kettle to boil water, make oatmeal, and pop corn. My favorite appliance is the Dash mini griddle. I’ve tried

mini quesadillas
ground sausage
hamburgers
pancakes
scrambled eggs

Having 120V electric appliances at camp means you don’t need a fire to cook.

My favorite use while camping has to be running a 12V electric blanket. I have a blanket with a 1 hour timer. I turn on the blanket, get warm and fall asleep, and the blanket shuts off automatically.

Around the house

I also take my power station all around the house and garage when I’m tinkering.

Nissan Xterra with the hood up, tools in the foreground — Jackery running a soldering iron

Plug in a lamp for more light
Vacuum the truck
Heat soldering iron for wiring
Run a pump sprayer to wash the truck
Trickle charge a battery

Power without an extension cord is very convenient.

Power outage

When the house power fails, having portable power stations really shines. Just like when camping, I can cook and have light and a warm blanket. More importantly, I can run my laptop all day if needed. For a remote IT worker, this is critical.

Components

Battery

I saw the FLLEEYPOWER 12V 6Ah LiFePO4 Battery on Vine. Its small capacity meant it wasn’t going to run big loads for hours. P=IV, so 144W would use 12 amps (12A) at 12 volts (12V). This battery is only rated for continuous discharge of 6A in 1 hour, or 72W, and 144W for 3-5 seconds. The dimensions are small though. I thought it would fit in an ammo can.

12V Output DC Power

You’ve seen them. The round 12V socket, a.k.a the cigarette lighter outlet. A common 12V fitting on all cars. My truck has 4, one of them I installed myself on the rear bumper.

You can plug in many car accessories. USB chargers, portable vacuums, tire inflaters to name a few. Most any automotive parts shop will carry a panel with a pair of USB ports, a 12V socket, and a couple of switches. I got the FXC Blue 3 switch panel from Vine.

120V Output AC Power

The big deal in portable power is AC power, or line power, or 110 power. It’s the power you get in your house when plugging a TV into a wall socket. It’s provided by the local electric utility company via the electric grid. In portable off-grid systems AC power comes from inverters.

Inverters transform 12V DC current into 120V AC current. Refer the Edison vs. Tesla cage match. For AC power on the battery box, I only had a few amp-hours of capacity, so I settled on a low power inverter. The Bapdas 200W car inverter fit the bill. Plus it has a voltage display.

Fuse Block

Current flows cause heat. Heat causes fires. Circuit protection stop fires. Fuses protect 12V circuits.

A fuse block combines separate circuits, easy fuse replacement, and common neutral bus bars. Separate circuits lets you add multiple switches and different sizes of fuse depending on load. I got a 6 fuse block from POWO Carlife.

Switch

Who doesn’t like a chunky switch? When I saw the tall 100A shutoff switch from Autoxbert I knew I was going to drill a hole and mount that switch inside the box. Most of the fancy electronic power station have a push button on/off switch.

Case

I thought an ammo box, a tackle box, or some other type of lidded box a handle would work well. Plastic would be cheaper and easier to modify. I couldn’t find what I was looking for on Vine, so I ordered the Sheffield ammo can from Amazon.

I made sure I had the measurements for the battery, fuse block, and inverter before ordering the box. Everything needed to fit inside or outside, on the sides or top. Round divots in the lid, the same side as the chunky switch, solidified the selection.

Solar panel

The ultimate off-grid power source is a solar panel. But solar panels are tricky in this case. For a 12V system, most “portable” panels are the size of 2 pizza boxes. Most of the panels showing up in Vine are 5V 3W-5W. Way too small to power even this modest system.

Charge controller

Bigger solar panels usually run at higher wattages with more variability. For example, a typical residential panel generates current from 12V on cloudy days to 18V in full sun. A charge controller regulates this voltage fluctuation and provides the correct voltage to the panel. I did find a 10A controller from Enovolt on Vine.

Light

Ever wanted a flashlight that will run for days? Every power station comes with a light. I had a 12V LED light in my electronics grab bag.

Construction

Measure once, cut twice. I think that’s how it goes.

The construction process began once all the materials had come in. First I stuck the battery, fuse block, and 12V sockets in the ammo can to make sure it all fit. I try to take into account routing and bending wires.

I broke the three switches that came with the 12V sockets at this point. The set was fully wired from the factory. But not how I wanted it wired. The wire lugs were firm. So I ordered some small but fine metal switches.

Next comes drilling holes. You don’t want to run a drill bit into the battery once it’s mounted. The cutoff switch was an 1/8″ larger than the divot. Nothing that a step drill bit and steady hand won’t handle. The light switch went in on top too.

The base plate for the 12V sockets was just wide enough to require cutting the lid bracing. Because I had already tossed the switches, I tossed the plate and mounted the sockets directly to the ammo can. I already knew how far into the can the sockets and wire projected.

I prefer to solder and shrink wrap connections. This gives a stronger joint. But ring terminals make it easy to wire a fuse block. So I solder the wire to the ring.

wires with crimped ring terminals showing soldered connections — For crimped terminals, solder the wires for extra strength

The inverter is mounted on the outside of the can. I settled on one side instead of the top. So I removed the 12V plug and drilled a hole for its cable. I put a hole opposite this for the solar panel cable. I planned to mount the charge controller inside.

The last hole was for the LED light. I found a vertical orientation worked best because the leads were centered and lay behind the lens. And the battery was directly behind the light, I moved the light to one edge so the hole would clear the battery.

After all the holes were drilled, it was time to lay out the wiring. Wires run from the battery to switch and fuse block. Wires lead to the sockets and light and switches and inverter. Wire to crimp, wires to solder, terminals to screw down.

wires and fuses in the fuse block — The fuse block sits between the battery and 12V sockets

Final mounting used some bolts, some flanges and nuts, and some feet of double sides tape. Overall it feels sturdy, but I wouldn’t want to drop it.

inverter with double sided tape on back — Double sided tape on inverter

Testing

I did a test of the wiring one leg at a time. Everything worked!

The LED light is not very bright but draws very little power.

The inverter displays the battery voltage, and loads over 100W run on it for a short time.

Both 1A and 2.5A USB chargers work. I ran the mini-fridge on the 12V outlet for about 15 mins and was satisfied.

The cut off switch is sturdy with a chunky feel. It works exactly as advertised. I’d like to add a custom cover to the terminals.

Neither a 5W nor an 8W solar panel I bought from Amazon were enough to run the charge controller. I’m considering buying a much bigger panel that’s capable of making 15V+ in direct sunlight. For now I’ve got a LiFePo charger to directly charge the battery.

Cost Breakdown

120V Inverter $25
Case $10
Switch $7
Small switches $12
Battery $25
Solar panel $18
Charge controller $40
Fuse block $11
12V sockets and switches $24
Total $172

This project ended up costing the same as a similar power station with a bigger battery and without the solar charging. If I did it again, I’d leave off the solar and get a LiFePo charger and larger battery.

A portable power station is a convenient and reliable source of power for anyone. I made one using inexpensive parts, the most expensive being the optional solar charge controller. Whether camping, working around the house or during a power cut, a portable power station shouldn’t be out of reach.

Thanks for reading. I had a lot of fun building this battery box: 4 full evenings after work to get it ready for a Friday camping trip. If you want to build one of your own, I’ve included Amazon affiliate links to the specific products I used. If you buy one, I get a commission but it doesn’t cost you any extra.

July 28, 2020August 27, 2020

Cooling Garment version 2

I wore the first cooling garment on a walk during a Fourth of July parade in a park. It was a hot day. After wearing version 1 for a few hours I learned some lessons.

Water leaks.
Vinyl tubing becomes stiff when cold.
Flexible bladders are hard to seal with glue.
Submerged pumps are harder to access.
Cold water in humid air collects moisture.
It was hard to route the hose.

I wanted to put some of the lessons into practice when designing my next cooling garment prototype. So the next version was quite different from the first.

The first thing to go was the backpack. It was too difficult to route the host through cloth layers. I didn’t like picking out seams to make holes. I wanted a frame I could sew the hose on to. I went looking for a mesh vest.

The mesh vest had several advantages. First, air flows through it. This could help with cooling and evaporation. Second, the holes in the mesh would allow easy sewing. Third, a fitted vest would hold the hose close to my body. I found a thin monofilament fishing line worked well for securing the hose to the vest.

I decided a rigid vessel to hold ice and water would be easier to seal. I purchased a Nalgene bottle with a wide mouth. I also purchased 10 feet of silicone tubing and right angle couplings. I drilled holes in the top and bottom of the bottle and glued in the couplings. Water flowed out the bottom and in through the top. The wide screw top lid allowed ice to be added.

I knew I wanted the pump to be outside the bottle. This would leave more room for ice. The addition of the couplers meant that I could add and remove the hose and replace the pump too. The downside of an external pump is the need to prime the pump with liquid before running. The liquid cools and lubricates the pump. The easiest way to do this would be to mount the pump lower than the bottle.

detail of mesh vest and silicone tubing — A tube from the bottom of the bottle leads to a pocket holding the pump.

I wanted to balance the weight across both side of the vest, as much as I could. So I ran hose from the left pocket and the bottle to the right pocket and into the pump. The pump runs on 5v from a USB connection. For this application, I used a USB power bank to run the pump. I ran the cable from the bottom pocket to the top pocket where the bank fits.

Choosing how to route the hose around the vest could have gone better. I needed a mannequin, or another large human model. I wanted the fit of the vest and the weight of the components to hold the hose against my body. I found three places that would work: pectorals, shoulder blades, and lower back. I asked my assistant to draw on the back while I wore it. I wound the 10′ of silicone hose around the back, securing it with fishing line. More hose would allow more coverage.

There’s not too much I can do about condensation. Move to the desert would be one solution. My t-shirt gets lines of dampness from the condensation on the cold hose. It does feel good anyway. I’m already planning version 3. It will be based on forced air ventilation. The moving air should help with evaporation and cooling.

Mesh safety vest — Me wearing the cool suit

July 4, 2018August 3, 2019

Cooling Garment version 1

I’ve wanted to make a self regulating cooling garment for a long time. I read an article, essentially the case study from NASA, around the thermal regulation suit designed for the Apollo astronauts. Ventilation and cooling underwear, this garment contained both cooling elements and channels for increasing airflow. The cooling liquid would lower the astronaut’s temperature when needed. Initially the design called for the astronaut to manually modify the temperature regulation of the suit. The later designs allowed for an automatic temperature feedback loop to be added to the mechanism. Cooling would then automatically apply to the garment as the astronauts worked during his mission duties and exerting himself.

The original designs for NASA Liquid Cooling and Ventilation Garment LCVG utilized close fitting garment in a single coverall. A long line of tubing was sown into the garment. The material of the garment also included channels to increase airflow to the extremities. This would increase evaporation and drying in a humid and enclosed space. For my own version of a personal cooling garment, I intend to use a close fitting garment which would be worn beneath any clothing. I have procured long underwear of a spandex and silk blend, which fits close to the body. I will use this in a later iteration of the suits. I want to test out various liquid circulation patterns and heat exchangers.

I’m starting with several different technology demonstrators to make sure that I have a reliable system for doing the cooling and ventilation. I plan on making several variations to test water cooling systems, using pumps and various means of cool in the liquid. The first design uses a typical water carrying backpack with removable bladder. Browsing Amazon, I found an inexpensive version which has a mesh fabric over the back with a padded channel for back ventilation. That space made it the perfect carrying unit for the cooling system. By cutting access holes intothe mesh fabric covering the padded back area, I was able to route a length of vinyl tube between the mesh and the padding of the backpack. The weight of the pack in this area would hold the tubing close to my body. The comfort padding on the backpack back would provide some space to prevent crushing the tubing. I procured a 10 foot length of vinyl tubing and routed the tubing through the back mesh part of the backpack. I routed the tubing into the main space of the backpack. I added two attachments on the reservoir in the back to complete the liquid circuit.

water bladder cooling unit — Water bladder and tubing

At this point I had roughly 5 feet of extra vinyl tubing in a loop. This tubing was handy for sticking down the front of my shirt. During the initial trial, and during the routing of the tube, I found that the vinyl tubing kinked when it bends too sharply. So I designed a minimum radius guide using Tinkercad, and printed this guide on my 3D printer. The design of the minimum radius guide was a flattened torus with a circular channel, hemispheric in nature, inset in the device. The channel was slightly larger than the diameter of the tube. When routed through the guide, the vinyl tube could not kink because the channel was too narrow.

A USB battery charger holds a large store of energy and provide a 5V output USB port. Mostly used for charging phones, the battery changer can power many other devices which run on 5 volts and use USB cables. I purchased a submersible 5 volt water pump, with integrated USB cable. This allowed me to power the pump and the entire water circulating system from a portable rechargable battery source.

The most difficult part of constructing the Cool Pac was securing the new tubing in a continuous loop to the reservoir. I was able to reuse the existing quick disconnect for one end of the tube. In order to attach the other end of the vinyl tube to the reservoir, I cut a hole in the vinyl reservoir and aligned the outlet port of pump with the hole. I then secured the top to the reservoir with CA glue and silicon sealant. The reservoir is by nature a sealed container. But in order to power the pump I needed to have the USB Power lead exit the reservoir. So I cut another role in the reservoir, and routed the USB cable out this. I secured the hole with duct tape and CA glue. I found this to be the weakest part of the circulation system.

My first field tests of the Cool Pac was at a July 4th parade in Stanton, VA. The parade took place in a park. My friend and I took our Astromech droids for a roll around the park. The temperature exceeded 90°. I filled the reservoir with ice and water and started the pump. The vinyl tubing did an excellent job of transferring heat from my body to the water. One downside of having a cold liquid in the humid air of summer is condensation. Condensation did affect the clothing worn under the Cool Pac. The exit hole for the pump power line was also a weak point, a point of failure. When bending at the waist, water in the reservoir would be leak out of this hole and run down my back. Overall the system worked reasonably well. The battery supply lasted the entire 2 hours. The ice completey melted after an hour, and the water circulating was no longer cool after 90 minutes.