SmokingCrow
Active Member
Growing to the plants full potential is about understanding what is holding it back. Using fluorescent lights and standard compost are probably the main reasons for ‘low’ yield of my last (and first) grow.
To that end, installing new LED lights was my first priority, as super soil seemed easy to make (for me).
Aliexpress, was where I started and called on my son’s expertise, an electrical engineering graduate, as well as months of research on various forums.
Premade, manufactured LED grow lights are expensive and I’m not in a position to spend the money. With that in mind, I decided to make them myself.
My design consideration:
50w full spectrum LED lights
heat sink and fan
The main design concern was heat dissipation, LED chips generate lots of heat and LEDs do not like heat. It did not take long for me to realise it was way to complex to design or calculate the right sized heat sink for the heat output so I guessed. 100 x 100 x 18mm aluminium heat sink with a fan blowing on it.
Does the fan blow or suck? It did not take long to find that I should align the fan so it blew air toward the fins; where would you stand when you’re hot, in front or behind a fan?
Two suppliers were chosen to supply the LED chips and there is no noticeable difference. Both are 50w full spectrum LEDs and 220v so I did not need to buy and size transformers. The 12v fans were 80 x 80mm and the cheapest on the site which in hindsight was a mistake as the fins are really fragile, but they do the job. Perhaps 220v would have been a better choice than 12v to make the electrics a little easier. A redundant 12v transformer is the power source for the fans.
The heat sink keeps the LEDs cool; they are about 23-26C, one of the test 12v transformers packed up and the fan stopped working. I touched the heat sink and it was hot, not so it sizzled and I did not get a blister. I expect it was around 60 or 70C.
The electrical engineer suggested that the power be parallel not serial. Using some leftover lengths of thin aluminium bar; one side as positive and the other negative.
The grow room is 2000mm long, the aluminium bar was 1800 (6’) and I had 8 units and drilled evenly spaced holes that matched up with the fans through this bar.
The process
Cleaned the back of LED chip and the back of the heat sink with alcohol/methylated spirit. Used a heat sink cement and stuck the LEDs onto the heat sink (centralised of course)
The lights were held in place by screwing through predrilled holes in the bar, through the fans, into the plugs between the fins in the heat sink. The bared 12v wires for the fans were then wrapped around the screws and tightened up for a good connection.
The 220v wiring was soldered into place and zip tied to the frame to reduce any tension on the soldered connections. I alternated the wiring so one plug powered every alternate LED, 200w each plug. This also allowed some form of light control.
Being aluminium bar meant the whole rail bowed when hung up. By adding an aluminium angle stiffened the entire rail.
The costs are detailed below:
LED 50 full spectrum £1.70
Fans 80x80mm £2.00
Heatsink 100x100x18mm £6.00
total £9.70
Less than a tenner about £13-14 USD
I’ll need to see if it makes a difference to yield. Please wait for about 3 months........although I've changed a few other things supersoil, compost teas and topping/training.
To that end, installing new LED lights was my first priority, as super soil seemed easy to make (for me).
Aliexpress, was where I started and called on my son’s expertise, an electrical engineering graduate, as well as months of research on various forums.
Premade, manufactured LED grow lights are expensive and I’m not in a position to spend the money. With that in mind, I decided to make them myself.
My design consideration:
50w full spectrum LED lights
heat sink and fan
The main design concern was heat dissipation, LED chips generate lots of heat and LEDs do not like heat. It did not take long for me to realise it was way to complex to design or calculate the right sized heat sink for the heat output so I guessed. 100 x 100 x 18mm aluminium heat sink with a fan blowing on it.
Does the fan blow or suck? It did not take long to find that I should align the fan so it blew air toward the fins; where would you stand when you’re hot, in front or behind a fan?
Two suppliers were chosen to supply the LED chips and there is no noticeable difference. Both are 50w full spectrum LEDs and 220v so I did not need to buy and size transformers. The 12v fans were 80 x 80mm and the cheapest on the site which in hindsight was a mistake as the fins are really fragile, but they do the job. Perhaps 220v would have been a better choice than 12v to make the electrics a little easier. A redundant 12v transformer is the power source for the fans.
The heat sink keeps the LEDs cool; they are about 23-26C, one of the test 12v transformers packed up and the fan stopped working. I touched the heat sink and it was hot, not so it sizzled and I did not get a blister. I expect it was around 60 or 70C.
The electrical engineer suggested that the power be parallel not serial. Using some leftover lengths of thin aluminium bar; one side as positive and the other negative.
The grow room is 2000mm long, the aluminium bar was 1800 (6’) and I had 8 units and drilled evenly spaced holes that matched up with the fans through this bar.
The process
Cleaned the back of LED chip and the back of the heat sink with alcohol/methylated spirit. Used a heat sink cement and stuck the LEDs onto the heat sink (centralised of course)
The lights were held in place by screwing through predrilled holes in the bar, through the fans, into the plugs between the fins in the heat sink. The bared 12v wires for the fans were then wrapped around the screws and tightened up for a good connection.
The 220v wiring was soldered into place and zip tied to the frame to reduce any tension on the soldered connections. I alternated the wiring so one plug powered every alternate LED, 200w each plug. This also allowed some form of light control.
Being aluminium bar meant the whole rail bowed when hung up. By adding an aluminium angle stiffened the entire rail.
The costs are detailed below:
LED 50 full spectrum £1.70
Fans 80x80mm £2.00
Heatsink 100x100x18mm £6.00
total £9.70
Less than a tenner about £13-14 USD
I’ll need to see if it makes a difference to yield. Please wait for about 3 months........although I've changed a few other things supersoil, compost teas and topping/training.
