What's inside a really expensive LED lamp light

I bought these really expensive LED lamp light for our new outdoors night lights. They even came with a 2 year warranty. I plashed out on these LED based lights, because:

1. They use less energy, hence are more environmentally friendly.
2. They last (supposedly) longer, hence are cheaper in the long run and are, because of this, more environmentally friendly as fewer materials are consumed.

 As a foot note, do not replace working lamps (incandescent or fluorescent) until they eventually burn out.

 

Since they failed in little over a year, I thought I'd do a postmortem on one of them.

The top is also a lens cover, and it came off easily despite being glued on, revealing the LED circuit board.

 

The circuit board substrate is metallic, and the board is thermally connected to a pretty hefty lump of metal with some white thermal paste, most likely silicone based. It is probably there to dissipate heat from the LEDs, or maybe give the lamp that "premium" feeling weight.

 

Now, removing the heat-sink and LED board reveals a second circuit board. Cutting of the mains legs frees the second circuit board.

The second circuit board is a relatively simple thing, a single sided PCB with a handful of components. There is a mix of surface mount and through whole components. Looking at this second PCB I feel a little disappointing, as this is where I would expect my very expensive LED lamp to distinguish itself from any cheap LED lamp, but at first glance it is a really simple passive circuit!

 

 

This second circuit board is just a simple diode bridge rectifier, with a few additional passive components thrown in the mix. On the AC input side are two resistors and a capacitor: 33 Ohm / 1 W, 1M Ohm / 0.25W, and a 0.90uF / 400V film capacitor. On the DC side there is one 2.2 uF / 400V polarized capacitor and a 300k Ohm SMD resistor. The diodes used are marked M7, which is a general rectifier diode rated for 1 A / 1000 V. I have 220V / 50Hz AC in my house, so straight of the rectifier bridge there will be a very rough 220V "DC".  I've not reverse engineered the circuit, but I'm assuming something is being done to lower the DC voltage, because the LEDs would not be able to take 220V.

The LEDs are "Natural" white 2835 SMD LEDs, which have a forward voltage of 3.2 V and 60 mA continuous forward current. There are nine of them in a straight series. This means the ideal DC voltage is 28.8 V.

I've traced the LED circuit to bring out the serially connected LEDs.

 

So there you have it. Certainly not worth the premium price, and since they lasted a shorter time than a normal incandescent equivalent, this is a definitive "Do not buy!".