30W LED with added 2.2UF film capacitor in series with Live wire.
Over the past year I’ve had to replace multiple LED lights with Day Night switch sensors in them. after multiple failures I decided to open one up to take a closer look at the cause for failure. Usually the LEDs are running hot and driven very hard from the factory so it’s not uncommon to see many black spots indicating burnt out LEDs in the light.
One way of extending the life of the led light is to reduce the power burning out the LEDs. This can be done easily by inserting an AC film capacitor in series with the live wire before connecting it to the light. this works great for reducing power and thus reducing the brightness of the light but it did not solve my issue.
2.2uf film capacitor helps reduce the power and strain on the LEDs.
In this case my light fails to switch on. when I opened it… The LEDs were still ok now on looking at the day night sensor I determined that the circuitry had failed. Failed how?
Well I had to investigate for a bit but eventually determined that the capacitive dropper was not supplying enough current for the transistor to swich from day to night. Why?
Day night sensor in the 30W light.
Well because the capacitor value had decreased somehow. seems that low quality film AC capacitors are used and their capacity drops maybe they deteriorate or loose electrolytic liquid I’m not exactly sure but when I replaced the capacitor with a new one everything worked again.
Faulty capacitor should be 220nf.
Replacement and faulty. Both questionable quality…
While load shedding continues to plague the average south African citizen I noticed that some of the well off citizens were not that phased out with the power going off and water running dry. Upon further investigation I found out that “big surprise” they had proper solar infrastructure and water tanks coupled with the right political connections they don’t need to suffer for decisions made by people who bear no consequence if that decision flops.
There’s nothing new about the facts I mentioned above however it got me thinking about looking for cheaper efficient and longer lasting solutions using technology even if they are not ideal its better to have something rather than nothing… what a shameful thing I had to say taking into consideration its the 21st century and governments are still using their governmental privilege to mess things up without facing a tar a feather spectacle such a shame..
Well unfortunately I can’t control things on a national scale but I can make a review of some affordable LED lights and hopefully that can help someone make a well educated effective decision to mitigate some of the frustrations and pain.
While browsing Takealot I noticed some prices fluctuate quite often but if you keep a price you are willing to pay in mind you can create a sort of mental filter that helps. So for this article I decided to search for LED lights containing these parameters:
Affordable
Rechargeable
Li-po or li-ion
LED light
5v to charge
Have an enclosure
Easy access and battery replacement
Decent circuit with charge protection
LED’s must not get too hot
I managed to find a product that came as a value pack (the so called emergency LED tube) and passed all my requirements. The product came as a value 3 pack of generic LED lights each light is about 32cm long and very light with magnetic discs.
I got mine at R210.00 for 3 emergency LED tubes that’s R70.00 for 1 so definitely affordable since I can’t get any 18650 battery for under R100.00 anywhere I have searched online in South Africa. I might just purchase these lights and harvest the battery in future just because it’s cheaper than purchasing the li-ion battery by itself.
Transistors
The lights come with 1x unmarked 18650 battery and a charge controller chip with 1 button and a female micro USB port to allow charging via 5v
The button allows the light to function in 3 modes: bright, dim and strobe.
Even though the listing claims these lights are 18w when I tested them at a theoretical max of 4.2v (li-ion battery max) I only got around 10w and the LED strip got hot.
4.2v running at 10.4W though box claims 18w (LEDs super hot burns skin)
Mystery chip
A few cons I noticed are:
Solder wires soldered directly on to the 18650 battery
Cheap solder
Some joints were not soldered sturdily
Blue end caps can come off easily sometimes
All in all the lights did work out of the box however I touched up a few joints and glued one end of the blue cap just so it doesn’t come out when hanging the light via the plastic loop.
Once fully charged the light has lasted through 2-4 hours of loadshedding with a few hours of charge time.
Overall the light does its job and is affordable and the battery can be swapped or cascaded for longer lifetimes.
The only major concern I have it the lifespan of the LED chips and the mystery chip but only time will tell.
While Java programming I started to wonder if I could program a pi board with java. During my research I found out that it is possible and there is the Java ME version that is specifically designed to be used in embedded devices.
Java ME requires the creation of MIDlets which is quite complicated so I decided to start by using the Java SE version and the WiringPi library. I’m using a Raspberry Pi Zero W with DietPiinstalled.
STEPS
Make sure Java & the WiringPi library is installed on your DietPi. Now open the dietpi-launcher.
Setting up the APP Compile the app with Eclipse. Now build the .class files into a .jarfile on windows. This makes one .jar file and compresses it for easy distribution. Make sure JavaSE1.8 is selected in Eclipse so that it can run on the PI’s openjdk version "1.8.0_212".
