Introduction: 576 Watt Hour Portable Solar Generator
Today I'm sharing my DIY 576wh Portable solar generator project.
For some time, I have hoped to inspire more people, and especially more ham radio operators to adopt energy dense battery chemistires, like the Lithium Iron Phosphates used in this project.
My personal inspiration for this homebrewed solar generator, was the grid down disaster in Puerto Rico during hurricane Maria. Many people were left without a renewable power source for refrigerating food/medicine, providing light, recharging phones or tablets, or powering ham radio stations to provide emergency communications during the telephone and electrical grid failure.
This solar generator along with a solar panel, could be a valuable asset, if such a grid down disaster ever presents itself again.
It's a long video, but also very complete.
Step 1: Test and Precharge Your Cells
I decided to use the Headway 40152 s lithium iron phosphate cells. You need to test and pre-charged yourselves individually before we can construct the pack. The first step is charging your cells to a safe voltage. I used the nominal voltage of 3.2 volts. I used my Turnigy charger to charge each of those cells individually, dentist did their internal resistance, then I place them into parallel groups of three. This configuration will get 45 amp hours out of the pack.
Step 2: Build the Battery Module
The battery module is the next part of the build. We're going to build the battery pack in a 4S 3p configuration. That means we have three cells in parallel and 4 cells in series. You'll have to decide what configuration you're going to put your cells in, but don't worry it really doesn't matter as long as you have them in 3 parallel 4 Series.
Step 3: Add Busbars and Balance Leads
The next step is adding the busbars balance leads to the pack. Be careful here though. There's two things you don't want to do. Firstly, don't connect the balance leads to the BMS yet, just to the 4 cells in series. Secondly, protect the bus bars from Short Circuit.
Step 4: Add BMS Wires
In addition to the balance leads, the BMS has two more connections which need to be soldered. There's the battery minus which goes to the negative side of the pack, and the power minus which is where we discharge the battery pack.
It's important to use the right gauge of wire here. For this project I use 10A GW wire to reduce losses and reduce Heat.
I also encapsulated the BMS between two cutting boards. Since this project is going inside an enclosure, I wanted to protect the BMS from rattling and bouncing around.
Step 5: Add Bluetooth Shunt
Since the wires for the BMS also passed through the Bluetooth shunt, we can go ahead and integrate the shunt into the system. The shunt has multiple ports on it but we're only interested in four of them. The two main connections at the front are for the shunt to measure current, then we need pins 8 and 1 from the Bluetooth shunt, to power the shunt, and to measure the voltage of the pack. The Bluetooth shunt takes the solar generator project to a whole new level, as it provides us with information about power coming in or going out current load Watts, watt hours, ...
Step 6: Wire the Fuse Box, 12 Volt and Usb Outputs
There's a lot of interesting steps here, and they're depending on the type of ports you use to get power out of the system. Naturally we're going to have a USB port. I used to. I also have four 12-volt ports, and two solar input ports. All of them are Anderson powerpoles. I also needed to decide on the fuse box. I used one specific to ham radio but, in hindsight I think I would simply use an automotive fuse box. I've already ordered it, so I'll update this project after I install it.
So the fuse block I'm using has one DC input four main power. It has 7 outputs with individual fuses for each. Then it has one pass-through DC port. I used 10 gauge wire for all of the ports. Each fuse for the DC outputs is 30 amps. The USB outputs are 5 amps combined.
Step 7: Working on the Enclosure
Next we're going to do all the holes in the enclosure. This is pretty easy but you need to mockup everything that's going in your enclosure, didn't mark the places on the outside where you're going to cut. I used to Titanium step bit. Measure twice cut once. I was initially going to use a metal enclosure but Not only was it too difficult to work with with the tools I had, it was a short circuit risk in general.
Those ports have locking rings and threads on them. So the locking ring in the lip of the port is wider than the hole we need to drill in our enclosure. The ports are all from Powerwerx including the backing plate.
Step 8: Integrating the Modules
By now you should have figured out we're building this so a generator in modules. The point is to be able to repair it if something ever goes wrong. That includes replacing the cells, or changing out the fuse block, integrating a new BMS, whatever it might be. The problem with commercial solar generators is there designed to be thrown away when they're done. Certainly you can exchange the batteries for example in the Goal Zero Yeti 400 lithium. But with the charge controller and electronics in that solar generator, they are not user serviceable.
Here's some tips to keep in mind when integrating everything inside the enclosure. Firstly use kapton tape on all of the conductive services before you start integrating all of the components into the enclosure. Next combine as many of the modules as you can so that they're easier to work with. Also, at this point in the build you can see the various modules and how they fit together. There was a lot of hand work in this build which you can see in the video, but it's pretty difficult to explain in writing or without hundreds of pictures. In this case the video is worth a few thousand words.
Step 9: Parts List
Everything in the parts list came from either eBay or Amazon. I used eBay and Amazon because here in Scandinavia these parts aren't so easy to find. Also, if there's any problem with the parts with eBay and Amazon, there's the buyer protection .
Headway LiFePO4 Cells: https://goo.gl/NencLf
Bestech BMS 4S LiFePO4: https://goo.gl/JYHJLD
Genasun MPPT Charge controller: https://amzn.to/2DTDse7
Powerpole USB: https://amzn.to/2DPzHqc
Alt Powerpole USB: https://amzn.to/2XacPKY
Powerwerx Powerpole POD: https://amzn.to/2V76azr
45A Powerpoles: https://amzn.to/2Xad7RT
Powerwerx Powerpole crimper: https://amzn.to/2X852NA
Thornwave Bluetooth Shunt: https://amzn.to/2ElUhkH
Full disclosure all of the links for the part list are affiliate links. These linked to help me to pay for the odds and ends that used to build these projects.
Step 10: Final Thoughts
Even if you follow the video or the steps to build a solar generator, each one of them is going to be different. We make different choices about the ports we use about the wires we use about the solar charge controller we use, and even the cells. The beauty of the solar generator is we can choose to build it the way we want. We make those choices which make it perfect for our individual requirements. So at the very least this guide, this solar generator is a template which you can make your own.
Now I'm completely new at this instructables thing, but I hope with time we can make this indestructible an awesome build.