Convert a 120VAC LED to 12V

       My quick Christmas eve project. I bought two used 120VAC LED floodlamps in the hopes of converting them to 12V for RE use. 120VAC lamps are useless over here as we have 220/240V mains.

       The LED lamps are Feit Electric model BPCE13PAR30L Rated at 13.5W 100-127VAC 650Lumens. This particular model caught my attention as the base was fastened with screws to the heatsink which meant I could easily take it apart.

       This is just a quick 2hr project so don't expect extremely detailed or step by step instructions, rather, take a look at the pics and notes on how I did it.

Here are the two used PAR30 LED lamps.

Removing the snap in TIR optics, we see warm white Cree XP-G LEDs. Nice!

Removing the optics holder, we can see that all six LEDs are wired in series.

The base is mounted with three small screws.

The driver is potted inside the plastic base. Fortunately, the potting compound is the soft kind.

Attacking the metal E27 base with a drill so that I can remove it.

A twist with pliers to dislodge it. The metal part is soft so don't apply too much pressure.

The base came off with a bit of effort.

After a bit of digging, we get deep into the driver cavity.

A few bangs on the workbench and it pulls out of the plastic base.

Here are the two drivers from the two lamps.

Although the lamps are the same brand and model, we can see that the drivers are completely different.

There is a small detail though. One lamp has a marked input current of 200mA (left driver) and the other 110mA but all other specs is the same.

Bottom side of the drivers.

This is the driver I used. It is a boost design and quite compact.

It is meant to be used for MR16 LED lamps. Description says: Suitable for 4~7 x normal LED or CREE-XRE, XPC, XPE series connection use. Input voltage: 12V; Output voltage: 12~23V; Output current: 300mA

A little underpowered for the LEDs but I think it will be fine.

I reused the original wires as it appears to be teflon insulated and too stiff for any other use anyways.

Reattached the base and added dents to prevent it from unscrewing again.

Tested with the powersupply. Consumption is about 0.5A at 12V input which is about 6W.

The lower power should be fine for better efficiency and it is still bright enough for my application.

Completed the conversion by marking it for 12V use. We don't want to accidentally plug it into an AC mains powered lamp base.



       1 Jan 2015:

       As the lights previously modded worked really well in the province, I decided to try again.

This unit is different but appears to use a single emitter in the middle.

Removing a trim ring reveals screws that attaches the optic to the heatsink.

The LED is a COB type with a measured Vf of about 30V

Driver is also potted.

I tried just gripping the screw base with pliers and forcing it just enough until it gives.

Some picking and banging on the workbench and the driver came out.

The driver looks to be good quality. Rubycon caps are used. There is also a 105C thermal fuse for safety.

Boost driver from DX connected to the base.

Reassembled, the new lamp runs at 1.2A with a 12V input. A little under 15W.

It was on sale, some up to 50% off! So I got a few more to play with!

Looks like the same driver will work. This one has a bunch of LEDs wired 5S3P with a total Vf of about 36V.

Yeah, they spelt "RoHS" wrong.


       6 Jan 2015:

       And work continues!

Now we tear down the wide beam angle lamp.

Now I got another one of these 120V drivers. I have no use for these as my mains is 240V.

Might be useful to scavenge magnetics and HV transistors

Bottom side

That's weird. Current draw seems a little low but it's pretty bright. Diode Vf is around 30V so it should take almost an amp but it does not.

Unfortunately, I noticed this after sealing the globe with superglue so I can't measure driver output current.

Tested the lamp on the hallway. It is actually a lot more yellow, the camera white balance corrected it.

Next donor. Diode array Vf is around 37V driven at 287mA.

Unfortunately, I'm fresh out of driver boards. More coming on the way!


       17 Jan 2015:

       Time to try something different.

This one surprised me. It has ten LEDs in series running at 60V 200mA.

None of the drivers I ordered can be used here so I thought of a different route.

Chopped up the MCPCB and rewired the ten series string to 5 parallel, 2 in series for a 12V 1A nominal LED array.

And I did not use any drivers. Just direct drive the LED array.

Full current occurs at a 12.7V supply voltage and then sharply rises after that.

Even at 11V, it is still bright enough to be useable.

I later added a 1ohm current limiting resistor for safety reasons as the current steeply climbs up above 12.7V with the risk of popping LEDs if the battery is fully charged.


       17 Oct 2015:

       I got a bunch of 12V LED bulbs that blew when a lightning struck nearby so I have a lot of the carcasses almost to be thrown away. What a waste. I decided to make use of the bases.

Here are some of the busted LED bulbs. These cheapies are rated 1.5W 12V

Here is one of the base cleaned and ready to receive new LEDs.

Hese LED strips mounted on alu core PCB are quite bright. This strip is warm white.

I used the micro table saw V2 with the fine toothed blade. It cuts quick and very cleanly.

The LED strips are temporarily held in place using hot melt glue.

The LED strips are arranged in a pyramid. This allows even dispersion in all angles.

The inside is then siliconed for strength. Using hot melt alone is not good since these LED strips get hot.

The top part is also siliconed.

Completed bulbs. These will be installed in the province, I shall take pics when I get the chance.

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