Sima Battery Conversion

In our opinion, one of the best infrared lights for night vision camcorders is the Sima SL-20IR. This lamp produces a “flood” effect (as opposed to the center-heavy spot of the Sony HVL-IRM) and effectively throws light anywhere for 20 to 30 feet.

There is one major drawback to this Sima lamp: it features a rechargeable battery that only lasts for about 45 minutes, limiting its usefulness in most investigations.  However, there is a way to convert these lights to run on AA batteries with some basic tools and supplies and we’re going to show you how.  Please do not attempt unless you feel comfortable using a soldering iron and an electric drill AND have an hour + to spare.

Supplies
  • Sima SL-20IR light
  • 4 -AA battery compartment like you can find at Radio Shack (or 3-AA if you can find one)
  • Heavy duty velcro (or another means of adhering battery box to light)
  • Soldering iron & solder
  • Wire strippers
  • Micro screwdriver – 1.2mm
  • Drill with apprx. 1/16″ bit
  • Small bit of electrical tape
  • Glue gun with hot glue (optional but helpful)
Step 1

Remove the four screws from the back of the light.  This proved to be the most difficult task of the conversion as these screws are recessed and very tiny!  You will need the smallest screwdriver you can find.  Be careful to not strip the heads of the screws.  Have a container ready to hold the tiny screws.

Remove the 4 recessed screws on the back panel.

Step 2

Pull the light apart, removing the bezel, red cover and silver reflector around the LEDs.   Remove three more screws attaching the LED panel to the back of the unit.

Three small screws hold the LED panel to the base.

Pull the circuit board out of the housing.  Using the wire cutters, snip the leads next to the battery pack.  You need these two wires to remain connected to the circuit board and be as long as possible.  Place the Sima battery aside for responsible recycling — please don’t just throw it in the trash.

What you have after the battery is removed.

Step 3

Open up the battery pack and take a look.  If you are using the commonly available 4 AA battery version, you will need to bypass the fourth battery position.  This light requires approximately the juice of 3 AA’s (it’s not exact but it works), and using 4 will overwhelm it and burn it out.

You will need to secure a single piece of wire from the positive terminal to the negative spring to complete the circuit.  HOWEVER, the metal in these packs is not readily conducive to solder.  I suggest gently pulling apart the plastic at the edge of the positive terminal in order to slip a bare end of the wire behind the metal. Secure it with a dollop of hot glue if you want.

Secure a wire from positive to negative terminal.

Next, run the wire across the empty chamber and wrap a bare end securely to the spring.  You can solder the loop together for additional strength if you wish. It’s not pretty but it works.  Be careful when changing batteries to not touch the exposed wire or you’ll get a shock.

Step 4

Drill a small hole through the back cover of the Sima light, near the on/off switch but clear of any circuitry.  Run the two leads from the battery pack through this hole.

Hole drilled in back of light, leads from AA battery pack running through it.

Step 5

Secure the battery box back to back of the light.  We used large velcro squares for this.  Keep in mind that you will need to be able to access either the on/off switch on the light or the battery box, preferably both.

Velcro pieces together.

Step 6

Break out the soldering iron and heat it up.  Twist the two black leads together and solder together.  Do the same with the red leads.  If you have a bit of electrical tape or heat shrink cover material, secure this around the exposed wires; otherwise, cover with a bit of hot glue.  You want to isolate this exposed connection from the rest of the circuitry to prevent an electrical short.  Position these new connections so that they are resting on the foam padding on top of the board.

Twist & solder the matching leads together.

Step 7

Test it.  Add batteries to the pack, flip both switches on and see if you have a faint glow (remember these are IR LEDs so your eyes barely see them).  If so, congratulations!  If not, double check all your wiring.  Eventually you’ll find the loose connection…which is most likely in the battery pack.

Switch it on & test before re-assembly.

Step 8

Re-assemble the Sima light with all its tiny screws.  Now you are good to go for several hours between battery changes.  Happy hunting!

Converted Sima light -- bulky but long-lasting!

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