I need a portable 12 volt power supply when I go camping. Having obstructive sleep apnea, I sleep with a machine providing continuous positive air pressure (CPAP) to my airway. The machine runs off 12 volt DC power, so the only trick is having a big enough battery.
One option is to buy a battery and solar charger package from the medical equipment suppliers that sell the CPAP machines. It is probably a surprise to no one that the medical market for stuff like this wants quite a pretty penny. Here for example are a battery and folding solar panel that together cost $625 + shipping as I write this.
Being cheap and a bit of a tinkerer, I opted to make my own. Here’s a pic of my setup.
The panel in front is a 20 watt unit made in China and marketed as Instapark. It measures about 24″ x 12″, the specs are on the product page at Amazon .
Behind that is a Pelican case, model 1300. Inside the case is a SunForce 10 amp controller and a PowerSonic 18 amp-hour sealed lead-acid battery. I bought various cables with the SAE two-pin quick disconnect and hooked everything up using heat shrink butt connectors. Including shipping I paid about $175. In addition to being cheaper than the medical supply units I have the flexibility of using it to charge a cell phone, Go Pro camera, or other electronic gadget.