This is not yet a finished project intended as instructions but only a means to share progress on the project.
This might be dangerous to attempt !!!
If you attempt to follow any of this, you do it at your own risk.
Adapting a mains AC led bar to work with a battery of 18650s
by lepi(lepi at-a hackerspace.pl)
KiCAD files: https://github.com/lepi00/portable-led-bar/tree/main/kiCAD-portable-led-bar
The purpose of this project is to adapt a 220AC UV LED-Bar to work with 18650 cells.
I have just started learning electronics, and my knowledge is very basic.
The LED Bar - Light4Me LED UV 8
|Light source:||8x3W UV LED|
|Light wavelength:||390-410 nm|
|Dimensions:||450 x 50 x 40 mm + 55 mm pins|
|LED driver inside (IP65):|
|Output Voltage:||27-36V DC|
|Output Current:||600 mA ±5%|
|TME Symbol:||Samsung ACCU-ICR18650-26H|
|Rated voltage:||3.63 V|
|Maximum current:||5.2 A|
|Charging Method:||constant voltage, limited current|
|Charging Voltage:||4.2 V ±0.05 V|
|Charging Current (standard):||1300 mA|
|Charging Current (max):||2600 mA|
Battery charger - Tangspower TP-L8S20 Li-ion charger
|Maximum Voltage:||8 * 4.20 V = 33,6 V|
|Charging Current:||2 A||Passive, PFC filter|
A friend of mine performs POI with POI-tails that are neon-yellow. The thing is made to shine in UV light.
Some AC mains LED bars I have, revealed a lot of space inside the casing profile - more than enough to house 8 18650 cells.
The LEDs have a “PowerLed” package soldered in-series upon a pcb with no other elements, but most likely have some resistor inside the package, as multimeter LED tester does not show anything when testing a single LED.
Remembering next-to-nothing about Electrical Circuits, I started designing a circuit, that would: - Power the LEDs from cells - Allow charging the cells without taking them out - If possible leave the original charger with mains connection
First I considered two solutions: - LEDs and cells in parallel
- Operating current would be 0.6 A * 8 = 4.8 A
- Charging current would be 1.3 A * 8 = 10.4 A
- LEDs and cells in-series
- Operating voltage would have to be 26.9 V (3.36 V / LED)
- Charging voltage would have to be 8 * 4.2 V = 33.6 V
- I have a TP4056 03962A Lithium Battery Charger with protection module
- Initially I thought that would be crazy to put 8 of these inside
- Also wiring LEDs in parallel would if I understand correctly require to put at least 40 cm * 8 = 3.2 m of thick wire - that might be difficult.
- A friend informed me to the fact, that I could use an external 33.6V charger which seemed to be easier.
- And also that I could use LM317 to regulate current out of the cells to LED's
- I decided to use a I/0/II switch and an IEC cord socket with the original LED driver if possible.
Emeryth suggested: - to learn more about li-ion cells before I use un-protected or multiple cells - to put some protection between cells and the cell charger - to use a DC-DC converter instead of LM317 that produces too much heat - to rethink if I need all LEDs in-series
- Research Emeryth's suggestions
- Find a solution to connecting the cells
- decide whether to solder the cells (dangerous, potentially capacity hindering)
- contact weld the cells (I don't have access to a contact welder)
- design a 3d-printed casing for the cells with springs, that would slide into the LED bar casing
- remember to discharge cells before in case of soldering