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Can you run two 48v led lights from a 24v driver?
12 July 2017
The simple answer to this question is ‘no’!
Your two LED lights each need a constant voltage of 48V in order to work correctly. If a different voltage is applied they may not work at all, or work very brightly for a very short length of time, or show some other form of malfunction.
If you want to run two 48V LED lights from a single LED driver then that LED driver must have an output of 48V and enough power to drive both of the lights.
Power is measured in Watts.
Hopefully, there will be some information supplied with the LED lights that states how much power they will draw. If this information is not available it can be calculated, so long as the LED light manufacture has stated at what current the 48V should be delivered to the light fitting.
You simply multiply the current (Amps) by the voltage to work out the required power (Watts).
So if your LED light calls for a 48V power supply @ 1.3amps, the power required is 62.4 Watts. (48 x 1.3 = 62.4).
As you have two light fittings you will need to double this figure, giving you a total requirement of 124.8 Watts.
It is advisable to allow some extra ‘head room’ to avoid accidentally overloading the power supply. Power Supplies Australia recommends that you only load a LED driver to about 80% to 90% of its rated maximum output. So, in the above example we would recommend using a 150 Watt or 185 Watt LED driver.
If you don’t intend to dim the lights, this is all you need to know.
If you wish to dim the lights then you need to go through a few extra hoops in selecting the best LED driver for the job.
First of all what type of dimming are you using?
If it is the standard wall plate leading/trailing edge TRIAC dimmer that you find in most houses, you will need a dimmable LED driver with ‘AC Phase Cut’ dimming.
TRIAC dimmers work by ‘chopping’ the AC power supply going into the LED driver. AC Phase Cut dimmable drivers have dedicated electronics on board that recognises the AC power is being chopped and reduce the light level accordingly.
If you try using a TRIAC dimmer with any other type of LED driver it will not work. The lights will not dim - most likely your LED lights will start to flicker or just go out completely.
There are only a limited number of AC phase cut dimmable LED drivers on the market. If you are struggling to find one with the required voltage and power output, then you may need to use a 1-10V dimmable LED driver. These can be used in conjunction with a 1-10V dimming control that can be slotted into your wall plate in place of the TRIAC dimmer.
Some additional wiring is required, as the 1-10V dimmer switch has two wires coming out of it which need to be connected to the dimming terminals on the LED driver. You will need a separate ON/Off switch to turn the lights on and off.
A low cost 1-10V dimming pot is available through Power Supplies Australia and is listed on this website under part # SDF-30.
All Mean Well LED drivers listed on this website with ‘3-in-1 dimming’ will work with the SDF-30 dimmer switch.
The other thing to note is that you will need to load the dimmable led driver to 80% to 90% of its maximum power rating as possible in order to effect smooth dimming.
This is because most dimmable LED drivers dim the lights by varying the current amplitude on the DC output side. If you have only loaded the LED driver up to 50% of its maximum rating then nothing will happen until you have turned the dimmer pot down past the half way mark, after which point the LED light will start to dim. This means that half the rotation of the dimmer has no effect on the brightness of the LED and you will not get an effective dimming range.
Power Supplies Australia recommends using the Mean Well PWM series where possible. The PWM series LED driver has a PWM output, which ensures even dimming regardless of the load on the LED driver.
If you have any questions about selecting a suitable LED driver for your LED lights then please do not hesitate to contact Power Supplies Australia on 1800 632 693, or use the ‘Contact’ link above to send us an E-mail.