Michael
The flood light have several main components:
1) Led
2) Led cooling
3) Led driver
4) lithium battery
5) aluminium housing
The description
1) Led
If i started 6 years ago with the project a 50W led was not know in our region and costs up to 100usd. Today i saw a led on ebay 100watt for 10usd ?
The challenge with this cob Led module is cooling. A 50Watt emit about 50% heat from the 50Watt power. And 25Watt heat in an electronic ciruit are very heavy.
2) Led cooling
I found a simple way for the flood light. I set some frame condition:
max led temperatur <90°C, the aluminium case schould below 45°C.
For the Led cooling thee was a simple trick, put enough aluminium on the led.
A aluminium block with about 100x100x20mm is enough for one 40min with 3000lumen.
In the meantime there would be a better solution: synjet from nuventix.
but this another project.
3) Led driver
This was my first boost circuit. I deside to you use the LT3756 from Linear.
The circuit is build from the application note as booster to work in a range 12-20V input.
Below 12V the current increase to much and the mosfet goes to hot.
It takes me 2 weeks to identified the right mosfet for the swiching circuit.
With minimal changes the circuit would be a buck-boost converter from 12V - 40V.
Brightness for the led could be changed with a poti.
The ic had also the possibility to use pwm for dimming but also another project.
You can download the eagle file from my private blog:
Steve Michel
danfer adrian
Joshua Snyder
macke