576 Watt Hour Portable Solar Generator

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About: YouTuber, blogger, and retired broadcast engineer. I love amateur radio, making tutorials, and sharing interesting projects with the world.

Hello Operators
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.


73
Julian oh8stn

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 .

Parts List:
Headway LiFePO4 Cells: https://goo.gl/NencLf
Bestech BMS 4S LiFePO4: https://goo.gl/JYHJLD
Enclosure: https://amzn.to/2BGleMV
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.

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    8 Discussions

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    mialjojo

    Question 2 months ago on Introduction

    I get an error when I try to download. I'm logged in

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    OH8STN

    2 months ago

    I just thought I would post a breakdown comparison Against The Goal Zero Yeti lithium and Goal Zero Yeti Lead acid.
    Breakdown is based on the cost of the gene per 100 watt hours, over its lifetime. This is a much better way of understanding how much the generator costs in comparison to others.

    IMG_20190222_213317_833.jpg
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    seamster

    2 months ago

    This looks awesome! Thanks for writing out the steps, this is a great looking first instructable. Well done!! : )

    2 replies
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    OH8STNseamster

    Reply 2 months ago

    You're too kind. When I look at your instructables, I see I have a long way to go. Thanks for the comment though and the guidance.

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    OH8STNseamster

    Reply 2 months ago

    Thanks for the kindness. I'm still learning, but really enjoying the platform. Thanks for the guidance on my first instructable.

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    zappenfusen

    Question 2 months ago on Introduction

    I’m actually a licensed electrician, retired, feel like an idiot but what is Kapton tape? I hear it named daily. Haven’t got clue what is being referenced. I built a similar project using smaller lithium’s. Also invested in natural gas generator. Savannah hasn’t been Hurricaned in years but I’ve lost last frozen food stores I’m losing in this lifetime.

    Good job,
    zappenfusen

    2 answers
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    OH8STNzappenfusen

    Answer 2 months ago

    Hey thanks for the kindness. It's very much appreciated. Kapton is a temperature stable tape, which tolerates huge temperature ranges. Cold or hot doesn't exhibit any shrinkage, and is an excellent alternative to heat shrink.
    The only reason I didn't use smaller cells was fewer points of failure. I have built smaller generators based on 26650, but in the end the larger cells are easier to work with, and turn out cheaper over the life of the generator.
    Thanks again for the question and the kindness.

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    CJP_techzappenfusen

    Answer 2 months ago

    Kapton is a brand name of a polyimide film often with a silicon adhesive on one side. It can withstand temperatures up to 500F or 260C. Also not electrically conductive. Can be safely used in electronics.