This post on arfcom caught my eye. Rather than buy a 12v lamp for use with a battery, this fella converted a regular household AC lamp to run an LED ‘bulb’ off his 12v battery.
This sort of thing intrigued me and I decided to try it. While we have several options for lighting around here, I’d like to have something that doesn’t look like the kind emergency lighting youd find in a stairwell. Something very subtle and ‘normal looking’.
A quick trip to Amazon for the necessary parts:
- E26 MEDIUM to 1 Pin BAYONET Base Light Bulb Socket Converter Adapter
– converts a regular screw-in bulb socket to the bayonet-type.
- Roadpro 12V Fused Replacement Cigarette Lighter Plug with Leads
– replaces two-prong AC plug with cigarette lighter plug
- GRV Ba15s 1156 1141 High Power Car LED Bulb 24-5050SMD DC 12V Warm White Pack of 2
– LED light that goes into the screw-in-to-bayonet adapter
The next step was to pick up a lamp to experiment on. As it turns out, I found a lamp that already ran on DC (it used a transformer to run off AC house current) and was LED. Since that was 2/3 of the battle right there, I figured I’d start with that.
Reading the details on the made-in-China transformer said, if they can be believed, that power draw was something like .33 amps. 
Conveniently, they labeled the wires as to +/-. Simple matter to cut the transformer off and connect the wires for the cigarette plug to the lamp wires…keeping the polarity the same.
Once the transformer had been removed and replaced with the 12v plug, I plugged it into my old ConSci battery pack to test.
Unsurprisingly, it works. I’ll tuck it away with the battery box and leave it for the next time I need lighting when there’s no available electricity.
Of course, the bigger plan is to use it in conjunction with the larger battery backup system I’m planning. Nothing fancy..a couple big deep cycle batteries, a smart charger, and a bunch of outlets and wiring to allow me to run emergency lighting and communications for a week or so on battery power. Thats the bigger post Im working on. Gonna be a little while on it, though, since it’s going to take a while to scratch up the cash for the batteries. But…when it’s moved from ‘theory’ to ‘in progress’ there’ll be plenty of posting on it.
I have a similar need for our single room cabin at the bol. I have a single 75 watt panel, that I will use to set up some very basic led lights, and a ability to charge batteries,phone etc. Its on the short list, so it should be done b y the end of summer.
Look to boating sites for info. Lots of cruising blogs describe just what you want. I have read some can go on solar alone for charging. Batteries, use golf cart 6v wired to 12v. They are about 50 bucks each at Costco. They even have caps to reduce wet loss. Or auto water system that keeps them topped off. As I recall, one blog couple stayed out in the Bahamas Out Islands, away from the crowd, for three months. They used solar and a wind gennie, a R/O water maker, and a Engle fridge/freezer unit. And yes, current draw is around 0.2-0.3. Back in my day, we used Alpeneglow fluro lights. Current draw was around 0.5 each. Made by a guy in Montana somewhere. Now they do LED. Lots of info there.
https://www.alpenglowlights.com/
Forgot the fridge.
http://www.engelcoolers.com/fridge-freezers?SID=1bbca6108f25f37090aabb3d4e90366e
Start building your backup system right now, i would suggest having the batteries in the center of the basement or in a cabinet in the center of the house, then have all your llghts and outlets as close to the batteries as possible, there are huge losses in 12 volt systems. Small drain users such as small leds may have their plugs further from the batteries, but anything big should be in the center of the building. Implement the planned 12 volts lights in the house right now and if necessary put a charger on your batteries in addition to any solar panel. One battery for 100$, or even your old truck battery that failed to start the truck on the first cold october morning is a good start, then you can replace the battery when funds allow, and then add to the battery bank as funds allow.
If one radio receiver, a number of the lights in your house, and your ham and CB-system is run from batteries now, you will know the capabilities of your system when TSHTF, you will also have rounded the edges and sanded any snatches down.
or be safe and use bigger wire to make up for the voltage drop and put the batts outside.
One 75 AH car battery is about one Kilowatthour of 12 volt electricity.
Though, of course, you shouldnt use a car battery, but a CV battery or other deep cycle battery, unless the car battery is free or really cheap.
Just be aware that if you you a traditional Lead Acid battery like a golf cart (deep cycle) or car battery (starter) that those batteries produce hydrogen gas when being charged. By code such battery banks are required to be in a positively ventilated box or outside. If you want to avoid the issue (after all who likes flammable gas in a house near electrical bits that can spark), use more expensive AGM batteries like a bank of Optima deep cycle (http://www.amazon.com/Optima-Batteries-8016-103-FFP-BlueTop-Starting/dp/B006QH55YM/) or Odyssey (http://www.odysseybattery.com/) or even Lithium-Ion battery banks which don’t out-gas when being charged.
I went glass mat on the boat first. Those things are much more fragile. Mine did not last a year. You must be very careful charging them and keep them in stable conditions. After I went golf cart, they lasted 8 years without much attention. Keep the fluid levels up (checked about once a month, clean the post about every three months and call it good. The Balmar alternator’s internal controller did the rest. I used the golf carts in a boat, as do a lot of cruisers. There is not that much off gassing going on. I agree keep the wire runs short. Just simpler.
i hardwired 12v rv lights all around my basement with leds. look for the long use leds as regular car leds are made for momentary use, not hours at a time due to heating. run them with 4 100ah marine batts hooked to two harbor freight kits. batts were 100 bucks at sam’s. rv sockets off ebay by the dozen.
I just noticed that Costco now stocks golf cart batteries in the battery/tire section of the warehouse. Didn’t look at the price or data on the batts, though. I see that they stock Interstate brand car batts now, and the price is waaay cheaper than the local Interstate distributor wants.
Unfortunately, both of my vehicle’s batts are not carried by them. You would think the Ford Ranger would be covered, but it was an odd size batt, so they have never stocked it.