Portable 12 volt power is critical to the field radio operator. Normally we use small lightweight battery packs to power our HF Radios for a few hours at a time, during field day, SOTA, POTA, .. When we are faced with a Grid Down emergencies, brown outs, black outs, portable emergency power becomes much more complicated. Not only do we need to ration the power we have, we also need to come up with ways of recharging our battery storage, when depleted. Some operators use combustion generators, some power communications gear from their vehicles. others deploy solar generators for emergency power, when it is most practical to do so.
This blog serves as the documentation page for my diy solar generator project. The introduction video for this project is just a few lines below. In that video we go through my concept for a man/woman portable, 576 watt hour 12 volt solar generator, to power our field stations, lighting and other essential devices, for a maximum of 24 hours before ever plugging in a solar panel. This DIY Solar Generator concept could be applied to a variety of field communications scenarios, where grid power is lost or not available. Most importantly, this concept could be applied as an Emergency Communications Go Box “Power Module”, providing clean efficient power for extended field communications.
The 128wh Headway battery builds were the testbed for a larger Headway builds to come. Understanding how to work with those cells, how many amps we could pull from them, and how safe they would be to work with when building on the channel, were all critical steps in the process.
When those builds were completed, many operators wanted to continue forward, turning the Headway packs into a full battery box. Many others wanted to take it to the next level, turning it into a complete micro-solar generator (it is a solar generator 😉). Others wanted to understand how to increase the capacity of these packs with parallel sets of batteries…
Well I agreed, but the channel had little in the kitty to start building right away. That’s not a bad thing, since we needed some experience on the 10ah Headway pack anyway. So after a few popular videos, blog posts, and help from PayPal, Patreon, and supporters who share the videos and blogs, getting the message out there, the components started coming in.
Solar generators and portable off-grid or grid down emergency power are popular topics on YouTube these days. Canadian prepper is doing the Inergy Kodiak videos, Jehu has done a DIY Inergy Kodiak, and there are even more videos and tutorials out there, some good, most bad. One thing each and every one of them is lacking, is that connection to how it’s going to be used in the field. It’s fine for someone to stand in front of a camera from their living room, telling us how good something is, but it’s not enough. Without showing a field deployment with a Solar generator in the real world, in a real or simulated grid down scenario, the videos would lack some much needed credibility. There’s also another issue. In emergency communications and grid down preparedness, there’s a certain expectation that one is able to repair their own gear. What happens if that Goal Zero Yeti or Inergy Kodiak has an component failure? What happens if there is a failure inside your Bioenno Power 120 or M400 battery pack? Could you repair it? Certainly buying something off the shelf can save valuable time and resources, but it leaves us vulnerable if for some reason, the device fails. Building your own solar generator means you understand each component in the system, how to troubleshoot, and naturally how to repair it.
X Days Off Grid
ANYWAY, I’m hoping with what we’ve learned from the 10 amp hour Headway builds, and the x days off grid series, we can put our heads together as a community. This way, we can combine our skills and experience, to build a better (more practical) solar generator for the emergency communications, field communications and grid down preparedness communities.
Amongst other things, the X days off grid series was designed to measure energy requirements for the field station, where only batteries and solar power were available as an energy resource. We always knew we were going to build a larger solar generator, but needed field experience before doing so. Having much of that experience in hand, we start the next steps in portable power, moving closer to a fully self-contained Field Station, completely autonomous from grid power.
If you’re new to my channel or blog and want to catch up, here are all the battery and solar power videos up to date. Portable Battery & Solar Power for Off Grid Communications:
The DIY Solar Generator
The first video in the DIY Solar Generator Project was the Headway unboxing on the DIY LiFePO4 channel. In this video you can see the cells I’m using for the solar generator build. I also talk a little bit about the project and what it’s all about.
As is always the case with my channel and blog, the focus on this solar generator is the balance between capability, portability, and run time.
- It has to be small enough to carry
- It must have enough capacity to provide 24 hours of energy autonomy while providing continuous power for the field station
- It must be compatible with our chosen Yaesu FT-891, Raspberry Pi, and Android Tablet for field communications.
- It needs powerful enough ports to run high power inverters, for a short periods of time during an emergency.
The project will avoid compromises in the quality of the cells, BMS and charge controller, and all ports used are Powerwerx and Anderson Powerpole, (which will hopefully provide a long, trouble free life and return on investment.
Here are some of the features for the solar generator:
- ~45 amp hours or 576 watt hours.
- 50A sustained current draw through the BMS.
- Main power switch
- BMS LVD Reset switch
- Built in digital current shunt to measure current in and current out, estimated time till flat, estimated time till full, current voltage, …
- 4x fused 45A Anderson ports.
- 2 x switched & fused USB ports
- 1x fused/switched high output port for an insane operator with a DC powered field amplifier, or to plug in a Pure Sineway inverter.
- Android app to display current load, voltage, time until flat, time until full, …
- Built into a 30 cal ammo box (hopefully) 😀
The current shunt is one of the most often left out components in diy solar generator or battery box systems. Even commercial solar generators like the Inergy Kodiak lack a current shunt instead, they rely on cheaper Chinese voltage meters to display numbers ham radio operators understand, but foreign to most other users.
Usually builders add a voltage meter as a gauge to understanding the state of the battery. The benefits of using a current shunt over a voltage meter is understanding every aspect of the batteries condition. The Power coming In, the power being used, voltage remaining, voltage coming in from the solar panel, load, …
Features & details
- Remotely monitor two DC voltages, current, power, energy (Wh), battery state of charge (in percentage and Ah), and temperature
- Measures voltage up to 60V and current up to 60A using the internal current shunt
- Sense up to 160mV of voltage drop across an external current shunt, allowing 300-600A currents to be measured
- Controls a power relay or SSR (Solid State Relay), low / high voltage disconnect, over-current disconnect, remote ON / OFF
This build will use a Bluetooth current shunt from thornwave.
Headway 40152S LiFePO4 Cells
The project uses 12x Headway 40152S 15Ah 10C LiFePO4 Cylindrical Cells, with screws. They will be configured 4S3P for a theoretical maximum current output 450 amps 3x 150A. Thankfully it’s not the current output which we are after it’s the capacity which is most interesting. 4S3P yields us ~576wh
- Nominal Voltage: 3.2Volts.
- Dimension:40±1mm X 165±1mm (with screw)
- Capacity: >15Ah.
- Maximal Charge Current: 3C (45Amps).
- Max Continuous Discharge C-Rate: 10C (150Amps).
- Maximal Discharge C-Rate: 15C(225Amps).
- Max voltage: 3.65±0.05Volts.
- Min. Voltage: 2.0Volts.
- Lifecycle: 2000 Cycles.
- Weight: 480Grams.
- Impedance: ≤8mΩ.
- Chemistry: LiFePO4.
The DIY Solar gen will use the PowerFilm FM16-7200. It’s 120 watt thinfilm, flexible solar panel. The thing that makes it different from most other portable solar panels is being backpack portable. I understand the cost of this panel puts many potential buyers off. Feel free to substitute this panel with whatever panel fitting your budget and needs.
It’s important to plan the solar panel in addition to the solar generator. Often in a grid down scenario, people rely on charging the solar generator with AC power, thinking the solar generator will be ready when they need it. It will be, for the few hours that it last. Certainly a solar generator can act as battery backup during power outages, but the reality can be a little different, if the power outage last longer than the capacity of your solar generator. Food for thought.
Genasun Charge controller
I’m planning on using the Genasun GV-10 charge controller for this build. It’s designed specifically for lithium iron phosphate batteries in 4S configuration. It’s also RF quiet for our HF Communications.
I’m also considering the victron charge controller since they are programmable and also quiet. I have one incoming, so let’s look at it later on.
The DIY solar generator will be mounted inside of one of two different enclosures. I thought the 30 caliber ammo can, or the Pelican case 1400. I prefer the ammo can because of it stop loading cover, but of course working with metal is more difficult and requires insulation between Electronics in cells. The Pelican case is quite nice but I just can’t get used to the idea of its size and top cover. I really had my heart set on an ammo can style box. I don’t have the top loading ammo can style Pelican case, and can’t justify the cost when I have these just sitting here.
I decided on the following DC inputs and outputs.
- 2x switched USB ports
- 4x 30A Powerpole ports for DC out.
- 2x parallel Powerpole inputs for two solar panels.
For solar inputs I’m using yellow housings positive, black negative on the powerpole ports. DC outputs traditional black negative, red positive. The idea is the sun is yellow, so the yellow input differentiates the DC outputs.
Cutting the enclosure holes
I used a titanium 28-29mm (1-1/8) step bit for the Panelpod holes. It’s important to do a mock-up of all the components Inside the Box, before drilling the holes. the mock-up doesn’t have to be perfect, but it should give you an idea of what goes where, and how it’s going to fit.
There’s more info coming.
DC Power distribution
The power distribution center is courtesy of K9JEB. He makes and sells these boards on his website to create a sort of DIY powerpole distribution board. I like these in the shack, but I haven’t been very happy with them when working portable. The issue was the upward facing connectors. With that said, the circuit board is a magnificent solution for creating a power distribution center inside the enclosure of the DIY solar generator. So this power distribution center will create order, where there would have been an incredible mess of wires. It will also act as a fuse block and blown fuse indicator, making troubleshooting incredibly simple.
Less is more!
The Inergy Kodiak is awesome, but it is also unnecessarily expensive. We can forgive it because much of the cost is tied up in storage capacity. Unfortunately it’s still tries to be all things for all people. For example, these six AC Outlets and the internal inverter used to power them. That all helps add to the cost of the unit. Realistically, if we change the way we think about what is really required during a grid down scenario, we can agree nobody needs 6 AC outlets. If someone says they do, they’re not really planning for a minimal off grid footprint. The Kodiak also has the cigarette lighter ports instead of real ports (coaxial xt60, xt90, …) to get DC power out of its batterystorage. So it’s primary design goal is getting AC power, out of the system. Even with an efficient pure sinewave inverter, it seems awfully wasteful. The inverter may be efficient, but converting DC to AC then back to DC to power your device certainly is not.
The Goal Zero Yeti 400 also has its own benefits and deficiencies. It has a coaxial output, multiple USB ports, a single AC port, but unlike the Kodiak, all of it ports suffer from low current draw capability. The DC output on the Yeti only supports 10 amps maximum. Seems like a good solution for a blogger on a camping trip but not for real grid down preparedness.
The Bioenno power M400 is a better value than the Goal Zero Yeti, but again tries to be all things to all people At first look, the DC outputs seem well thought out:
- 1x 12V Marine Car Socket with 10 Amp Maximum Discharge
- 2X 12V 6mm Coaxial Socket,m with 3 Amp Maximum Discharge
- 2X 5V USB Socket with 2.1 Amp Maximum Discharge
- 2x 5V USB Socket with 1.1 Amp Maximum Discharge
- 1X 12V Jump Starter, 200-400 CCA
- 2X 110VAC AC outputs
Where is the 20A port for the QRO radio? Perhaps we are meant to use the jump starter port to power our radios!?
It also seems Bioenno power I can’t decide if this pack is lithium ion or lithium iron phosphate. The documentation is conflicting.
Each of those products offers advantages in a grid down disaster scenario. None of them are bad, but as radio operators, none of them are a good either. Bottom line, It’s not until we design and build our own solar generator, that we can get the capabilities we actually need.
Emergency communications and preparedness
The other batteries built on the channel have been focused on portable Communications. We built those batteries to power the radios, smartphones and computers we use, while operating in the field. As many of you know, the channel has its roots in disaster communications. Lots of bloggers and YouTube channels use buzzwords like grid down, off grid, shtf, disaster, … to increase the potential views on the videos and blog posts they make. Fair enough, but we need to define what we mean by emergency communications and grid down preparedness. This solar generator project can power a 100 watt radio for about as long as you need it, unless you’re at the North Pole during winter, then you’re probably good for about a day. This solar generator is also designed to be an effective power source for grid down disasters such as Puerto Rico in Hurricane Maria. Hurricane Irma, people forced to bug out from the California fires, or any number of disasters we face every year, around the world. It doesn’t matter if we’re trying to power a smartphone or tablet, lights for our camp, or a small refrigerator to keep our food fresh. with a well-designed solar generator we can do all of those things Plus provide portable power for off-grid emergency communications.
One thing I often fail to mention of my videos (because I’m focusing on Communications for preparedness, is a solar generator of this type is also good for car camping, temporary off grid power for your boat, RV camping and boondocking. These projects and videos would probably get a lot more exposure, if I could be more generic with production. At the end of the day, I’m a radio operator. That’s where my focus is.
In my preparedness planning, the solar generator should power:
- My HF & VHF communications gear
- Emergency lighting
- A DC powered refrigerator (if it’s required)
- Electric kettle (fire preferred)
- Recharging headlamps
- Charging or powering entertainment gear.
One can also see how this DIY solar generator would make an effective battery module for an emergency communications go box. The functionality of this solar generator is limited only by our imaginations.
I’ll be creating videos about the DIY solar generator over both YouTube channels and the blog.
Finally this post is work in progress, so expect updates as we get closer to the build.
If you’d like to help push this project forward faster, use this link to buy some Powerwerx or Anderson Powerpole gear from ebay: https://goo.gl/5dvGEa
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