Guest Post by Bill Osuch (My Husband)
I’ve been interested in learning about solar power for a while, but starting out by converting our entire home to solar seemed like overkill, and one of those folding solar cell phone chargers was just too basic. I decided to build a simple, low-cost solar battery that we could use on both camping trips and in case of power failures for some basic lighting, gadget recharging, and other uses.
A quick Google search will come up with many sites giving step-by-step instructions; I followed the plans at Ammo Can Solar Power Supply, but there are loads more out there. Most of the components were purchased on Amazon or eBay.
Just about every system will have the same three basic components: a solar panel, a battery, and a charge controller. The solar panel supplies the energy, while the battery stores it (obviously), and the charge controller is basically a switch that turns on and off to charge the battery when it’s low and prevent overcharging when “full”.
I’m not going to go into too many of the technical details regarding the design (volts, watts, amp hours, etc.); you can read through the actual instructions for a better understanding of this. The circuit looks like this:
The solar panel has a cigarette lighter plug to connect to the battery box, which is then connected to the charge controller. The output of the charge controller runs to a terminal block, where two sets of wires run to the battery and to an output cigarette lighter jack. You can then plug in just about anything that you would plug into your car.
Everything fits nicely into a plastic ammo box, which should actually be relatively waterproof. I certainly wouldn’t recommend leaving it out in the rain, but it should survive the morning dew just fine.
I haven’t done extensive testing yet, but I estimate we should be able to run an LED lamp for about 3 days solid on a single battery charge. Of course, you can expect more than just 3 days, since you’ll be recharging every day during daylight hours. You can also charge your portable electronics, run fans, use small cooking devices, etc.
You’ll have to either learn the math to do the calculations or simply experiment to determine how long your battery will last with various types of devices. The beauty of a solar system like this is that on a basic level, they’re all the same, whether you have a little handheld one like this, or larger system supplying power to your home or RV. You can easily start to add on more (or larger batteries), more solar panels, a larger charge controller, and even an inverter to convert the 12-volt output from the battery to something you can run household devices or appliances on.
I built this mostly as a proof of concept, and to take on our camping trips. My next project is going to be a full-blown solar generator – I’m picturing a 4-wheeled garden cart full of batteries, a large (several feet across) bank of solar panels on the top, and a power inverter. The goal will be to run lights, a computer, a small fridge, etc. during a blackout. We’ll keep you posted!