Outdoor solar powered LED garden lamp / Tear down.

[Kiriakos GR]

I just found today one of those single LED garden lamp, which I actually rescued  it from becoming as permanent trash.

After a close inspection the only problem was that the battery was heavily discharged.
I was not aware that those lights are using AA NiMH, or even better I have never be interested to see what those devices hide under the hood.

The solar panel dimensions is 55 X 55mm, the voltage output with out load is 2V.
Even if similar ones on eBay it supposed be able to offer 60mA max, I am suspecting that this one it can give about 40mA as real power.
My measurements shown 1.30V at the battery side and 1.20V actual voltage at the LED side,
The circuitry draws 11mA from the battery and the LED 2.9mA, you are free to comment the efficiency  factor of it. 

The most interesting in this design is this ANA618 IC which works as battery controller.
What it does is to control the LED when there is no electricity coming from the solar panel.

The all concept is truly smart, as soon the panel is unable to deliver more than 200mV  this event works as trigger and the IC activates the battery as power source and the LED.


Unfortunately I did not have a better luck from many others in the past, about locating the datasheet of the ANA 618.
What looks important is to be aware of the ultimate volts and current limits.
The single LED solution does not offer usable light, and so what comes next is the idea to do some tweaking on it.

Currently I am testing it with three LED in parallel.   

Enjoy the pictures. 

[Kiriakos GR]

Pictures set No2

[Kiriakos GR]

Pictures set No3

An simple drawing about parts and connections. 

[ElectroElvis]

Very interesting terdown, I had one in past and when I took it apart was even more simplier. My solar panel had 4 contacts underneeth. When it was functional LED turned on when I covered panel with my hand, but there was no IC inside circuit, so I assume that 2 extra pins on solar panel were for some sort of light sensor.

Elvis

[Kiriakos GR]

This little Solar device become a reason to me, for a close observation for about 10 Days.
Luckily I had a mixture of days with 100% clear sky and also few cloudy days.

Here is my conclusion summary in titles.

a) Those lights can fully recharge the inner battery only if they are placed in open space (garden) with out surrounding bindings or trees.
Alternatively they will function properly on a balcony which is facing south.
If the sun is blocked to them even for the half period of the day, those lamps are unable to operate.   
 
b) At a cloudy day that the sky is 100% covered with clouds, those devices are unable to recharge.
By having a day that the sky haves openings on the clouds, equal to 60% Clouds & 40% clear sky, the lamp managed to get 80% of charge.

c) The offered light from the lamp is so few (single LED designs) that honestly they do not have a practical use at all.
The very cheap versions of those lamps is just a decorative toy, which needs the climate of South Europe to support it functionality.
 

[Kiriakos GR]

This is a follow up 12 months later

I am attaching two pictures of the top side of it which was exposed for one complete year in my home.
I was had install it on the height of  three meters above the ground level so to be under direct sun light for the 3/4 of the day time, which is the best result that I could get.

Problems:

1) Unfortunately the shiny clear top surface were burned and become blurry.
Try ed to clean it with soapy water = Fail
Special cream scratch remover = Fail

The chemistry of this clear varnish does not respond well in any soft cleaning agent.
No I did not use alcohol or anything powerful, this would actually make things much worst.  

2) The NiMH battery are now completely damaged.
I did replaced it with a Lithium-ion 1,2V cell , part of one 2,4V Cell phone battery (extremely old Nokia phone part).
Just the thought that Lithium-ion gets less effected by low temperatures than Ni-Mh, made me move forward and  try it so to see how it goes.

3) Small living bugs found their way in it, so to convert it in to a nest.
Particles of dust and moisture formed a black layer of dirt over the PCB side, which is reversed in this design.
I did clean it up and added on it one layer of finger nails varnish, so the PCB and solder points to become water proof.

In summary:
 
You get what you payed for !! No this is very untrue here.
No one can be aware or predict the quality of the solar panel prior be exposed to the elements.

While the plastics ( case )  they did pass the test by not becoming burned ( hard and fragile ) the solar panel and the design it self is not that waterproof so to survive in time.

They use to say that solar technology in our days is capable to serve for 20 years and be trouble free,  well I can not speak for the true solar panel cells, but this single mini cells are not robust enough.

My advice is .... Beware when spending on eBay 50$ or more money on solar chargers with such quality of solar cells, you are buying garbage with limited life-cycle.
They might be functional for occasional use, but there is no chance to maintain their what ever performance after a true period of  use for 12 Months.   

   
 
 

[Kiriakos GR]

This is a follow up Three Years later.

I am currently exploring potentials about using another type of battery, and just discovered something very interesting.
This controller over this PCB is also one pulsing mini step-up inverter.

While I am using LED which require at minimum 2.4V DC,   this mini step-up inverter creates a pulse which makes those LED to turn-On even from a single volt ( this is what the multimeter measured).

By connecting my Oscilloscope I did discover the all truth, even with 850mV DC at the battery it self, the output voltage driving the LED is almost 1.2V at almost 200KHz.

1,5V from regular DC source is unable to turn-On the LED.


 

[Kiriakos GR]

And here comes the last and final update.

This is how the pulse looks like with fully charged battery = 1.50V 
In conclusion this thing feeding the LED with square pulse which according to battery voltage, this pulse can vary from 200KHz - 500KHz .

I could never imagine that this thing it does hide so much engineering in it.


 

[Kiriakos GR]

Gentlemen    time for one update ...

There is a new kid on the block and this is  YX805

This controller by a single LED has an output of 3.0V , I am now experimenting adding five LED in parallel (voltage drop this is 2.68V)
This YX805 it is a bit different speaking of wave generation, now this chip producing something simile more to triangular pulse.

[Kiriakos GR]

When plastic die you need a new home for the electronics - Made in Greece by Kiriakos

[Kiriakos GR]

I came across a solar powered toy this operating with QXS521 controller.

Unfortunately QXS521 controller this is restricted to handle 1.5 Volt battery and voltage output.
There is no hope converting this so to handle several brighter 2.8V LED.
It can only power up a single LED due it current limitations, output this is square wave at 160KHz at 1.8V Max

Very specific toy this is terrible as lights source but still it is good enough as gadget to impress an five years old baby.
Internal battery this is Ni-mh 1.2V 40mA.   

Working voltage: 0.7V~1.5V
 Input current: 1.2V / 22mA (47uH)
 Input current: 1.2V / 16mA (68uH)
 High efficiency: 84%
 Internal integrated light switch

[3xSpecs]

Never too late to include a ANA618 datasheet. Chinese and English.