Solar Ammo Can

by Ben N on March 2, 2018


With my recent work in solar, quite a few people have started asking me about designing small BATTERY-based solar systems.

I thought it would be nice to work on a project demonstrating basic solar battery charging principals, and at the same time, have a handy and useful project when I was done. Thus, the Solar Ammo Can was born!

I chose to use a 50 caliber plastic ammo can/storage container. It’s a nice size, has a sturdy handle on top, and is weather-proof. I’ve used a lot of these same containers as tool boxes and for storage. They are great for camping supplies.

Here’s an overview of the project and what it does.

Of course, actually assembling the project is a little more complicated. On the other hand, I really did mostly use off-the-shelf parts (or mail order at worst!) I did that to make sure that the project would be made from straight-forward components anyone could get. Here’s the step-by-step assembly video, followed by the list of components.

For this project, we used:

MTM 50 Caliber Ammo Can

Sealed Lead Acid Battery, 15AH capacity ​

20A Solar Charge Controller

Four In One Socket Panel

Banana Jacks

12 AWG stranded wire in both black and red (From local hardware store)

Crimp on electrical terminals,

spade and 1/4″ ring terminal

Silicone adhesive or hot glue

Industrial type hook and loop fastener (Velcro)

Wire Nuts or Wago (Brand) Lever Lock Nuts.

Fuse Holder and Fuse.

6-32 and 8-32 nuts, bolts, and washers

PV Solar panel. Any 12V nominal solar panel of about 10 to 20 watts is perfect for this project. Here’s one which looks affordable, and it about the right size and style for the project.

DC Power Adapter (Wall Charger) Any DC wall power adapter of higher than 12V (13.2, 14.4, 18) and one amp will work fine. I already had a 18V 1.3A power adapter handy. Here’s a similar adapter.

USB Gooseneck LED Light These small USB lights work great. They are very simple and durable. Fantastic for camping.

100 Watt AC Power Inverter. This device converts DC power to AC power so that you can run typical household devices from a battery. A 100 watt version is very compact and inexpensive. I already had one, which I used for this project. Here is a similar version.

Once I had all the components, it was just a matter of laying them out and fitting them all in the box. Rather than drilling through the side of the ammo can (and wrecking the weather-proofness!) I decided that all the components should go INSIDE the box. To do that, I’d have to make some sort of a faceplate for the parts to mount to. I scanned the components so that I could bring them into a vector graphic program where I could arrange them, and then use that to make a cut file for a laser-cutter. I then visited a friend, and used his laser cutter to make the faceplate.

Assembling the components to the faceplate is just a matter of putting components through the holes and adding a few screws, nuts, and washers.

For the electrical, I just followed the schematics on the Solar Charge Controller and the Four-in-One socket panel. The main thing to remember is that all the power goes through the solar charge controller. Besides controlling the charge, this device also acts as a low-voltage cut-off to prevent loads from over-discharging the battery.

A main fuse is connected between the solar charge controller and the Positive side of the battery. I used a 20A fuse, as the charge controller and other components are all rated at a maximum of 20A.

Wiring was completed with 12 awg stranded copper wiring, color coded red for positive and black for negative. Wago lever locks are nice connectors that can take the place of wire nuts. They make solid connections, but also allow you to add another wire later, or remove one. They are great for prototyping projects!

I glued down the battery inside the ammo can and placed a piece of self-adhesive industrial Velcro on top of the battery. A matching piece of Velcro went on the back of the faceplate. After plugging in the battery wires, I simply Velcro’d down the faceplate over the top of the battery.

At that point, the Solar Ammo Can is ready for action! It’s handy for camping and emergencies. The Solar Ammo Can will charge a phone or tablet, run a light or radio, and can even run low-power AC devices. The Solar Ammo Can weighs less than 10 lbs, and cut easily be lifted and carried by nearly anyone.

I already had a solar panel appropriate for this project. I looked around to see what’s out there for an affordable panel that would match and found this one.
Here’s my video review and how to use it.

If you haven’t already, please take a look the YouTube videos, and feel free to comment either at the video on YouTube, or right here at
As always, please like, share, and subscribe!

Until next time, stay charged up!




Star Trek Doors Update Feb 2018

by Ben N on February 18, 2018

I’ve been working with my brother-in-law, Fred, for the last while, helping him out with a project. He’s always been a big Star Trek fan, and he wanted to upgrade a door he had to one done in the style of a space or sci-fi television show. We decided to make it air-powered, and I set to work learning about pneumatics and micro-controllers.

I shot this video last night to show you the current state of the project.

In a nutshell, this is a custom door (based on adding material to a hollow-core door) on sliding pocket-door hardware. Instead of manually sliding the door open, both halves are attached to air cylinders. The air cylinders have an air hose on each end – one to extend the rod, and one to retract it. A “Five Port, Four Way” air solenoid directs air from a compressor to one side or the other of the air cylinder, opening or closing the door. Power to the air solenoids comes from a pair of relays, which are controlled by an Arduino Uno micro-controller. Basic arcade style buttons send a signal to the micro-controller.

As it is, the air-powered doors work great, they just happen to be manually controlled by pressing a button.

The master plan is to fully automate the system. Since a micro-controller is already doing the actual control, all we need to do is add sensors and programing to make the doors open and close with some “IF…THEN….” programming statements. On the other hand, that’s actually harder than you think. This door is between a garage and a workshop. On the workshop side, the walking path is at a right angle to the door, but on the other side it’s a straight line. What happens when somebody pulls a car in to the garage?

It actually takes some clever design and planning to make the door open when you want it to, but NOT open the rest of the time. On television shows and movies, a human stage hand is usually pulling a rope to open the doors at just the right time. In our system, just a dumb computer will have to figure it out. Essentially, we’re trying to keep this from happening.

In the end, it might take several sensors of different types working together. Besides that, there should be some sort of safety mechanisms to keep pets or small children from opening the door as well as to prevent it from closing on them.

We HAVE experimented a bit with using a timer feature. By pressing one button, the doors open, pause for a set amount of time (a few seconds,) and then close. Overall, that worked well and was simple. The main downside is that didn’t allow for KEEPING the door open, and there was nothing stopping the door from closing on a person. (Just to be clear, the door isn’t so powerful that it will crush a person…)

Ideally, I think the door needs three modes – Fully Automatic, Manual Stay Open, and Manual Stay Closed. The Automatic version would keep the doors closed unless a person walked up to them with intent to walk through the doorway. The manual modes are self-explanatory, they would just be an override to hold the door open or shut.

As it is at the moment, the doors are working well for Fred. They are simple, reliable, and look cool.
Also in the video, the decorative trim of the door wasn’t installed. You can see it leaned against the wall to the bottom left of the door.

The door is very functional in that it is insulated and between a heated and unheated workspace.

Keep your eyes peeled for future updates when we add some automation! If you are a master of the micr0-controller and know of some good code for automation and ideas for safeties, send them our way!

Until next time, stay charged up!


PS: The original information about this project is located at:


Tesla Model 3 First Viewing!

by Ben N on February 11, 2018


Yesterday, I got my first chance to see a Tesla Model 3 in person! Let me say, I LIKE it!

This is the first Model 3 in the state of Wisconsin. We were holding a Wisconsin Tesla Owners and Enthusiasts meeting at a restaurant in Madison, the state capitol. The meeting was a social gathering, a technical meeting (talking about issues concerning Model S door handles,) and a chance to see the M3. I was mostly there to see the car.

I shot some video of the car being shown off. In it is some of my thoughts, and you can catch some other members saying what they like and what they notice about the car, too.

My first impression of the car is that it looks good! That’s to be expected of Tesla. All of their vehicles of attractive, aerodynamic styling. I loved the red color, and the proportions were nice. The hood design is a little different. The hood itself is actually just a little LOWER than the headlights. The headlights have a nice crisp line that flows from the lights to the front fenders. Likely, this is for aerodynamics, the same as the headlights on the Nissan Leaf, only Tesla makes it look good.

IMG_7829The nose is slightly different from the original announced version. It looks better, but it’s hard to say exactly what’s different. Perhaps just a softening of the radius?
Also on the front is an interesting “pass-through” on the bottom outside of the front bumper. These holes allow air to flow from the front of the car, through the edge of the bumper, and the create an “air-wall” past the front wheels, improving aerodynamics.

Another feature that I noticed right away is that the door handles are different. This was interesting, because at the meeting, the technical portion of the show was talking about the door handles on the Model S, and how they have become a maintenance issue. Those handles are electronic and automatically present themselves as the driver walks up to the car. They are also overly complicated and prone to problems. The Model 3 handle is much simpler. It’s still flush to the body of the car, but is on a swivel. Pushing the handle with my thumb, the other side of the handle levers out to be grasped and pull the door open. This greatly simplifies the handle and saves weight, complexity, cost, and maintenance vs. the Model S.

Multiple cameras are visible on the outside of the car. Modern cars are getting more and more safety features, and Tesla is famous for being a leader in autonomous vehicles. It’s easy to see how they would install as many cameras as possible.

TrunkThe trunk of the car is interesting, and not quite what I was expecting. For starters, yes, it is a trunk, NOT a hatchback. This allows for the piece of glass which is seamless from the middle of the roof, coming down and becoming the rear window, and finally ending at the trunk. The only distinction between roof and rear window is the gradient of heavy tint for the roof to very light tint for the window.

While small compared to a hatch, the trunk opening really utilizes the space available at the back end of the car. And the trunk is LONG – it goes all the wall up to the back seats, which are further up than one might expect at first glance. Besides that, there’s also a drop-down “hidden compartment” below the floor of the trunk. Lastly, a REALLY GOOD DESIGN ELEMENT of the trunk that I think everyone has overlooked is HOW the trunk lid is held open. It actually IS a hatch! Gas shocks hold up the lid, and those shocks are mounted OUTSIDE the enclosed trunk area. Traditionally, a trunk lid is held open from internal supports and springs. Unfortunately, those supports take up some of the interior room, and are notorious for pushing against suitcases. This always drove me crazy on my wife’s old Pontiac Sunfire. The trunk lid swings up very high, not unlike a mini-van hatch, preventing it from becoming something to hit one’s head on while loading cargo.

The “Frunk” is pretty unremarkable. It’s smaller than on the Model S. I guess what’s amazing is that we now have a car company where we EXPECT extra storage built in because of the lack of an engine! One neat little feature in the frunk is a pair of swing-down clips to hold the handles of shopping bags.

Once a few people had cleared out, I was able to hop into the back seat of car and check it out. I was pleasantly surprised that as a six foot tall guy, that I actually FIT in the back seat. Headroom can be SO bad in the back of many cars. When I tested the Chevy Volt when it first came out, the only way that I fit in the back was to lean all the way backwards until my head was inside the back window. On the Model S, the entire roof inside is a window! Not only that, but it’s a couple inches higher than I thought it might be.

27999101_10160364591725221_463720514_o_largeIn the front seat, the member testing the drivers position was 6 foot 8 inches tall. He sat with plenty of headroom to spare. Other people looking at the car all seemed to really like the glass roof. From the inside, it offers panoramic views. From the outside, the tint is so dark that you might not even realize that it’s glass!

I found the seats comfortable. They had a nice texture and just the right amount of squishiness.

Unfortunately, I didn’t get a chance to actually go for a ride in the car. The owner said that he loved driving it, and that it was maybe even MORE fun than driving the Model S. He said the cars just have a little different feel from each other.

Overall, this looks like a great car! I loved the color and styling. It has some nice lines. The dashboard is minimalist in a good way. The trunk is well-designed to really maximize cargo space. I think a lot of people are really going to enjoy these cars!

If you get a chance, definitely go take a look for yourself! These cars aren’t everywhere yet, but they are coming, and you will want to check one out.

Until next time, stay charged up!

-Ben Nelson

Photo Credits: I forgot to grab any interior photos, nor did I get a test-ride, so thank you to Brandon VanD for those. Here’s a phone vid of a test ride. Near the end of the video, you can see a 0-60 MPH test pulling away from a traffic light.


Disaster Preparedness with a Prius

by Ben N on December 31, 2017

1,000 watt inverter in a Prius

I commonly get questions about battery backups, generators, solar panels, and other provisions which might be useful for disaster preparedness.

There were plenty of disaster-related comments on social media at the end of September, due to Hurricane Maria hitting the coastline of the United States.

And while most of us enjoy fantastic electric service on the U.S. Mainland, RIGHT NOW, there are STILL places in Puerto Rico either without power, or only intermittent electric service.

My friend, Jomel, lives in Puerto Rico. Today, he posted to Facebook about using his Prius as a backup source of power. The original post was in Spanish, but Jomel was kind enough to give me an English translation, which I’ll post here. He also gives a more concise description of how to use a Prius as a backup generator than I ever could.

“Here we go again, no electrical service since yesterday December 30, 2017 at 9:00 am, so I will celebrate the New Year using the Prius. At this moment I have consumed 2.0 kWh in 7 hours and 40 minutes and the engine has consumed 0.68 gallons of gas, equivalent to 0.0887 gallons per hour.

I connected a 1000 watt Xantrex the true sine wave inverter to the auxiliary battery of the Prius. That’s a 12 volt battery that is been charged by the 200 volt traction battery via a DC to DC converter.

The engine doesn’t has to be running all the time. In my case, I leave the car in the Ready Mode, in Parking with the A/C Off and windows down for air circulation.

The engine runs for 2 minutes to recharge the traction battery and then stops for about 30 minutes, so in an hour it only runs for about 4 – 6 minutes. It’s a very practical setup since it maximizes the engine utilization, and it only runs at about 1200 RPM.”


One big advantage of using a hybrid car as a generator is that the engine doesn’t have to run continuously. That saves on noise and exhaust. A car with an even larger battery, such as a Chevy Volt would be able to run an inverter for a significant amount of time before the engine would need to activate. Battery Electric Vehicles would have an even larger reserve of power, but would not be ideal for long-term power outages, as they also need to recharge from an electric source. I’m sure we’ll see dedicated DC solar charging in the future. For now, solar charging is left to the hobbyists and smaller projects. A few years ago, I did power my entire house directly from my Electric Motorcycle. It was also configured to be able to recharge from a single 96 cell solar module.

Disaster preparedness could be as simple as using the car and other equipment you already have. Just make sure to have an inverter that can be connected to the battery. At 1,000 watts, that’s enough power to run a refrigerator, LED lights, a radio or television, and charge cells phones. A simple extension cord can be used to route power to wherever you need it to go. For people living in areas prone to power failures, they could even wire up their homes with a generator input and manual transfer switch.

I followed up with Jomel about the current status of electricity in Puerto Rico, and this is what he had to say:

“The electric power has always been very unreliable, the grid was very old and vulnerable. After Hirricane Maria, all the system collapsed leaving 100% of the island without power. At this moment only about 60% of the people have power. Some experts say that some people may be without power until June 2018.”


You can certainly see why Jomel has been installing solar panels for a battery-based system.

Levels of disaster preparedness vary depending on your personal situation. Public infrastructure and support certainly varies. Make sure to be ready with works for you!

-Ben Nelson

Special thank you to Jomel Maldonado for sharing his info and photographs!

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Snow Rake for Solar Panels

by Ben N on December 11, 2017

A few days ago, we got the first snow storm of the year. Not a big deal, but that was the first snow we had since I installed the solar array on my garage. I found that using a broom, even from a ladder, I could only clear the lowest of the three rows of panels.

After reading through a number of web pages, it looked like the most common way that people remove snow from their panels is with a roof rake. So, I found one at reasonable price and ordered it.

Last night, we got another dusting of snow, and as luck would have it, my roof rake showed up as well! It’s a SNOWJOE 21-Foot Twist-n-Lock Telescoping Snow Shovel Roof Rake Model RJ204M. Assembly was easy, just pop the plastic blade onto the end of the telescoping pole and screw on two small aluminum braces.

With that, I headed outside to try the roof rake.

Extending the pole is easy, just loosen by twisting, then extending one section of the pole (it’s four sections total) and then twisting again to lock it down.

IMG_7503At full length, the pole does flex quite a bit. The rake end kind of bounces, but it still feels pretty solid. I had the right amount of reach to get all the way to the top of the second row of panels, and that was WITHOUT a ladder! I could get part of the bottom of the third row of panels, but only if fully extended and with me right next to the building. At that point, I couldn’t actually see up the roof and had to guess at where the rake had landed!

I was hoping that if I could get at least part of the third row of panels that perhaps it would allow the sun to warm the panel and have the snow start to slide down. Although it didn’t get sunny today, it did get a degree or two above freezing for a while. Sure enough, the snow on the top row of panels DID slide down a bit, but not off the roof. Actually, it was almost worse. With the snow covering HALF a panel in the upper row and the middle row, I likely got LESS energy production than if the top row was completely covered and the middle row completely bare!

Using the roof rake is a bit of a workout. Anytime a person is working over their head, it’s always a bit tiring. To me, it felt like a deltoid workout not unlike paddling a kayak. (An like paddling a kayak, NOT something I do every day!) The roof rake itself isnt’ that heavy, (4.8lbs./2.2kg) but with it fully extended, it’s a handful!

Overall, the roof-rake does a pretty good job of clearing the snow from the solar panels. Good, but not perfect. I found that it got caught pretty easily on the mid-clamps that hold down the solar panels. It could also get caught in the gap that separates the rows of panels, although approaching at an angle seemed to help with that issue. A foam or squeegee head might run over the mid-clamps better, but might not bite into the snow as well.

IMG_7506It was also difficult to completely clear the snow. Seemed like there was always a little bit here and a little bit there. Even small amounts of shading on a solar panel can dramatically reduce energy production, so that’s not ideal. On the other hand, if the sun ever DOES come out, those small bits of snow should melt quickly. That’s the one last thing that I’ve been noticing so far with snow and solar panels – of course snow on the solar panels blocks light, but just HOW CLOUDY it’s been seems to have an ever larger impact on the power made.

That is to say that even though the snow is covering the panels, there’s just NOT that much light to convert to energy anyways! In my area, this is an extrememly dreary and gray time of year. Now, if it was SUNNY and the panels were covered in snow, THAT would be a different story!

For now, using a roof rake to clear snow off the panels seems like a simple and practical solution. It’s not perfect, and I certainly wish I could more easily reach that third row of panels, but for now, it’s more than good enough.

Until next time, stay charged up!