Maybe it is hurricane Dorian in the news, but I am really thinking about building a battery backup power supply. I already have a 5k generator so this would basically be a power supply for smallish electronics.
I have looked at several builds on YouTube, and some are quite sophisticated, while others are very simplistic. I have an idea of what inputs/outputs I want, but I don’t really know how to assemble the components, especially in an electrical connectivity sense.
Among the outputs I want to include:
4 USB ports
1 12v cigarette plug
1 DC to DC buck convert
As far as inputs, I would like to charge by 120 a/c and eventually solar panels for emergencies.
I would like to start with a 30(ish) amp hour 12volt sla battery and have the whole thing fit into a plastic.50 cal ammo can.
Since you already determined the battery and voltage, the rest is pretty straight forward:
The USB ports are readily available on all markets, just look for stuff to build into a car. Same with the 12v plug (although I cannot recommend cigarette plugs, they never work reliable for me).
What do you want from the DC-DC converter? (The USB ports will contain a buck converter already.)
Charger: 12V battery charger. Also available everywhere.
And then probably a 12V battery controller to protect the battery from over charge and discharge. And a fuse next to the battery in case you short it out.
Assembly: First you will have to determine the maximum current your system will see. That determines the wire size. (see AWG).
Battery connections: Hopefully your battery has something to screw a bolt into. Unless you need super high current, twisting the wire between two washers should suffice. If you want to to it properly, get some properly sized cable lugs. There are some for crimping and some for soldering. Crimping is faster, soldering has better contact … not that you would ever need that much current.
Other connections: I am a huge fan of screw terminals: Twist the end of the wire, insert and tighten the screw. To do it properly, use one of these as well. Also shrink insulation for the positive connections.
only other tip i'd give besides above is considered price comparing the finished product versus building yourself. The margins on this stuff is small and so you often can find solar panels and electrical equipment below cost of building or assembling yourself. If you are going to run something critical like a cpap you might also want to consider a finished product.
You make fair points. However, when I have done an apples to apples, cost/benefit analysis, I always seem to come out ahead (mostly I am comparing to the Goal Zero Yeti series). Also, I can customize as I see fit, a major reason I am attempting such an endeavor.
Most of all, I just like building these types of projects. It’s a great exercise in creative reasoning and I just love the learning experience and satisfaction when I am done.
It's a pleasure to see superheros taking such an interest in science. And this tiny ad: