Portable Sun - Rechargeable Work Lamp




Introduction: Portable Sun - Rechargeable Work Lamp

About: I also go by the Instructable user name: UnknownUser2007

Why use a flashlight when you can use a powerful, heavy duty work lamp? Flashlights run out of juice, are under powered, are hard to position and roll away when placed on the floor. How many times have you had to fetch your flashlight from the bottom of your driveway?

This Instructable shows how to build a powerful, rechargeable work lamp. The base is solid and stable since it contains a sealed lead acid battery. Once you position it, this thing stays put. The lamp itself is a car fog lamp so it will illuminate your entire work area. It is brighter than the sun itself!

The work lamp is also packed with a few extra features. It includes a DC/AC Inverter so it can be used as a battery back up. It also has a relay circuit which turns on the lamp in the event of a power failure. Cool to have when the zombies take out the power grid.

This Instructable should be titled “Harbor Freight Hack” since most of the major components come from Harbor Freight. Harbor Freight is a great place to pick up a wide variety of inexpensive tools. http://www.harborfreight.com/ HF is a Maker’s paradise.

Ammo Box - Bunker Hill Security - Item#61451 - Harbor Freight - $6

400 Watt DC/AC Power Inverter Cen-Tech - Item#66814 - Harbor Freight - $30

Automatic Battery Float Charger Cen-Tech - Item#42292 - Harbor Freight - $10

Enercell 12V/5Ah Sealed Lead-Acid Battery - Catalog #: 23-945 - Radio Shack - $30

Genssi LED Off Road Light 4X4 Work Light Waterproof 27W 12V 6000K (60 Deg Flood) - Amazon - $25

DC Power Jack - Catalog #: 274-1583 – Radio Shack - $3.99

DC Power Plug - Catalog #: 274-1573 – Radio Shack - $3.99 (2-Pack)

4 1N4001 diodes – Catalog #: 276-1101 - Radio Shack - $1.49

7812 Voltage Regulator - Catalog #: 276-1771 – Radio Shack - $1.99

100uF Electrolytic Capacitor – Catalog #: 272-1028 - Radio Shack - $1.49

Inline Fuse Holder - Catalog #: 270-1281 – Radio Shack - $3.49

Car Accessory Cigarette Jack – junk box

SPDT Relay - Zettler AZ942-1CT-12DE 16A 250VAC – junk box

SPST Mini Switch – junk box

Female USB connector from old PC backplane card slot – junk box

Nylon web strap with buckle – junk box

PWB Perf Board – junk box

Scrap pegboard

Scrap strips of aluminum sheet

Scrap sheet plastic


Metal Brake Bender
Hole Saw
Heat Gun
Soldering Iron
Tin Snips
Utility Knife
Atomic Powered Ruler

Step 1: Power Inverter Mods

First, disassemble the DC/AC power inverter. There are four screws on each end cap. Note how all the wiring is connected. Cut the wires to the AC receptacles and remove them from the enclosure. There are tabs that hold them in place. Desolder the leads from the receptacle.

Remove the fan and extend the leads about 6 inches. You can add an optional header to the board and a pin connector to make reassembly easier. Save the four mounting screws and fan guard since you'll be using them.

Desolder the USB connector from the subassembly board which holds the power switch. Extend it by soldering a USB cable connector. These USB connectors can be found on the back of old PCs. They occupy a card slot. These style connectors are great because they have integrated mounting tabs. Mounting a raw USB connector to a panel is difficult.

Step 2: Prep the Ammo Box

Mount the flood lamp to the top lid near the hinge. You'll need to cut off some ribbing on the back side of the lid before drilling a hole for the lamp bracket.

Create a template from the holes for the AC receptacles on the end cap of the power inverter. Transfer the template to the lower front of the ammo box. Using a Dremel and utility knife, cut out the AC receptacle holes. Using a hole saw, drill a hole for the fan and the 12V car accessory jack. Drill the remaining holes for the DC power jack, switch, USB connector and vent openings at the top. Note, one of the vent holes is used to route the lamp cable.

Step 3: Fabricate Internal Frame

One of the main design concerns for the project was airflow. The power inverter has a fan so the box needed to be designed to allow for adequate airflow. The internal frame was designed to have two levels. The lower portion contains the fan and power inverter. The top contains the relay board, battery charger module and power button sub-board for the inverter. The air gets sucked in from the front. Then it does a 180 degree turn to the upper level and then out the top vent holes. See the side view diagram for details.

First, fabricate the lower base plate. It should be sized so that it fits inside the bottom of the ammo box. The material used is scrap pegboard. A jigsaw is used to cut it out. Cut out some smaller pieces of pegboard and use them to block in the power inverter board. Position, then glue these smaller pieces to the larger piece. Allow room for the battery. See photos for more details.

Next, fabricate the four legs. The legs are used to hold the top plate. The legs are made from strips of aluminum sheet. Using metal snips, cut out two long strips. These are roughly 3/4 in. wide by 10 in. long. Bend these in a “U” shape and epoxy them to the lower base plate. Wait a day for the epoxy to dry. When dry, bend the ends of the four legs inward. Drill holes in each of these ends. Then thread bolts into these holes. The four bolts should be pointing upwards. Epoxy these bolts in place from the underside. See the side view diagram.

The 12V car accessory (cigarette lighter) jack comes with a “L” shaped metal bracket. Use this metal bracket as an upper support for the top plate. Just drill the end of the metal bracket and epoxy a bolt to it, similar to the support legs fabrication. See the photo for details. Solder a crimp lug to the bracket. This provides the negative power to the 12V car accessory jack. The top plate should sit on top of this bracket.

The top plate is made from 1/8 inch acrylic sheet. It was heated and bent to form a “Z” shape. First create a template in cardboard. The top level of the “Z” should be above the fan but below the DC power jack, switch, USB connector and vent holes. See the photos for details.

Transfer that template to the acrylic sheet and cut it out with a jigsaw. Using a metal brake and a heat gun, bend the acrylic to the desired “Z” shape. Next drill 5 holes that align with the bolts that were epoxied to the legs.

Fabricate a small mounting board for the inverter sub-board that holds the power switch. Use sheet ABS and screw the sub-board into it. Drill two holes in the ABS that align with the epoxied bolts on two of the legs.

Lastly, position the battery on the lower base plate. Create a slot in the plate so that the nylon web strap can be used to strap the battery to the lower base plate.

Step 4: Make the Relay Board

The relay board is used to turn on the lamp if the power mains goes down. This can be used as an emergency flood lamp. The way this works is that it monitors the power mains. When the power goes down the relay board turns on the lamp.

The battery charger has a small wall wart. The relay board monitors the output of this wall wart. A simple circuit keeps the relay coil energized using the output of the wall wart. When the power mains goes down, the relay coil de-energizes which flips the lamp on.

Unfortunately, the output of the charger wall wart is AC so it must first be converted to DC. The relay coil works only with DC, hence the need for the relay board.

The construction of the relay board is simple. It consists of a diode bridge and 7812 voltage regulator. Install the components per the wiring schematic then solder everything.

Next, modify the battery charger. Cut the wires from the wall wart and install a DC power jack and plug. (The photo shows the float charger module with the cover off. Prying the cover off isn’t necessary.)

Lastly, position the battery charger module and relay circuit on the acrylic top plate. Drill and tap some mounting holes.

Step 5: Final Assembly

The final assembly is the best step. It’s a culmination of all your hard work.

Paint the parts, as needed.

Mount all the front components: AC receptacles, fan, fan guard, 12V power jack, DC power jack and switch. Then position the power inverter board and mount the USB connector. Using crimp connectors wire up the AC receptacles and battery terminal leads. Thread the battery strap through the plate and bolt the plate to the ammo box.

Using more crimp connectors wire the fuse holder to the 12V accessory jack. Install the top plate and mount the inverter power switch sub-board, relay board and battery charger module. Following the wire diagram, wire up and solder the remaining circuit.

Test the circuit by flipping the lamp switch on. The lamp should light up. Then plug in the battery charger wall wart. The lamp should turn off. You should hear the relay toggle. Test the AC power by plugging in a desk lamp or similar appliance. Test the 12V car accessory by using a multimeter or inexpensive cigarette lighter type voltmeter.

Congratulations! You finished! Enjoy your new portable sun!

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    .NetRolller 3D
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    5 years ago

    Could you make a version with an 18650-based battery instead of an SLA?
    You can get quite a significant weight reduction that way.


    Reply 4 years ago

    With the capacity of that SLA, you'd probably wind up saving a bit over 2 pounds. (3.3lbs vs 1.1lbs), but costwise it's a comparison of 30 vs 75 bucks, plus the need for specific connectors, and that the Lithium packs don't have the kind of amp output capability. The weight is worth the money savings, since this project is fairly stationary. And all-in-all is probably less than 10lbs total.

    Plus, Lithium doesn't like getting hot, so you'd expend more power keeping the inside of the case cool constantly, over the only needing cooling for the inverter. I've tried both, and I'll say my SLA battery packs last a lot longer in the Arizona heat than my Lithium packs (flat OR 18650).


    6 years ago

    Great project and well explained. This will help with my lighting issues on my boat project.


    6 years ago

    Great and very well done Instructable!


    7 years ago

    im using 12v dc battry, with 500w inverter to 220v, when the main power goes down, let me know how to install RELAY, and which type. ... thank you


    8 years ago on Introduction

    I thought I was the only one to use an Ammo Box to house Electronics. Glad I'm not, cause they sure are nifty for Projects.


    Reply 8 years ago on Introduction

    They sure do! It's keeping my final project safe from the elements (and scoundrels) when transferring it to and from school. My teacher saw that I was housing my custom PCB's that I had designed, and the ribbon connectors for it inside the container, and mentioned how it was an "Interesting Containment unit". Especially to be brought to school, but I added stickers to the side to make it look less conspicuous.


    8 years ago on Introduction

    I have something a bit different

    Bought a light stand and an E27 socket for the light stand, a diffuser cover for the lamp, and a 12V lamp

    I use a 12V battery I once bought, and now it's in my UPS, constantly charging :)


    8 years ago on Introduction

    Just what every vampire hunter needs!


    8 years ago

    might be cheaper, as well as more efficient to DIY with the Led fixture to achieve a minimal input of say 12v. should be lighter using a buck converter and lithium ion batteries.


    8 years ago on Introduction

    Really great Instgructible and guide. THanks. :)


    8 years ago on Introduction

    This is a great Instructable. I've got two Kawell Slim 18w Flood Beam units that should work great for this.


    8 years ago on Introduction

    I just had another thought - you can get cheap UPS's (for PCs etc) that already switch over from mains to backup power automatically - you could fit that into the ammo case, cut the loud annoying buzzer off and use the buzzer voltage to drive your relay for the LED light. Achieve much the same thing, except that you don't need a separate charger and inverter. And if you replace the usually pathetic battery in those cheap UPS's with a larger capacity battery, you might get better run times too.