Converting Outdoor Transformer Lighting to Solar (p1)

I use 3x 18W lights to decorate my front yard.  This is a total of 4.5A at 12v.  During a recent visit to Anchor Electronics (www.anchor-electronics.com) I found blade style LED high power LED lamp assemblies.  These lamps are built on a PCB consisting of 6 LEDs, a discrete rectifier (to prevent polarity on connection), and a power management chip.  My immediate thought was to convert my 18W lamps to this LED lamp.  Each lamp uses 20mA.  So in total my yard lighting would be 60mA instead of 4.5A.  This is more supportable with a battery backed solar setup.

I started the experiment of determining if this would work by converting one burned out bulb to take this lamp.  The following pictures show the steps but read the end instead of following this.  First I taped up most of the glass of the bulb.  Using a plastic wrap I made a base to hammer the bulb to break the top of the glass (without the base, the actual base of the bulb would get damaged).  Next I uncrimped the tungsten and crimped on the pigtails of the LED lamp holder.  I solder gobbed the crimp connection (I believe in belts and suspenders for my electrical connections).  I had o solder gob instead of solder because the tungsten carrier is not easily soldered to.  Finally I filled in the space in the lamp with non-conducting plumbers putty. Installed the LED lamp and fired away.  OK, it took more debugging to get this to work as it turned out that pushing the LED lamp completely into the holder shorted the diodes and prevented operation -- so the LED lamp assembly needs to be pushed in but not all the way.

As it turns out this worked very well.  The 20mA unit was about 75% (qualitative) as bright as the 18W incandescent bulb.

If you want to do something like this, an easier way would be to source the parts from:
http://stores.ebay.com/Auto-Gangster-2009?_trksid=p4340.l2563  -- i ordered parts from here
http://stores.ebay.com/id=1007915828    -- have not ordered from here
http://www.superbrightleds.com/  -- have not ordered from here

After I get my COTS lamps, I will work on converting the transformer system into a solar powered setup instead of mains powered.  Stay tuned.