The most common questions we’re asked are “Which driver should I use?”, “Will this driver work with your boards?”,  “How do I dim my boards?” and “What is the difference between a constant voltage driver and a constant current driver?”

Let’s answer some of those questions first.

Which driver?

All the drivers we sell have a dimming function, and all our High Light boards and kits come with driver recommendations on the Products page. If you already own a driver on the list, it will work with our boards. But there are other drivers not on the list that will also work with our boards – it simply comes down to which driver gives the best result for any particular application.

If you don’t have experience with LED drivers, the options can seem daunting. But driver choice usually comes down to how many boards you wish to run and how hard you want to run them.

The harder you drive your LEDs, the less efficient they are – though losses are typically in the region of 5-10%, up to around 15%.

Some growers like to run higher numbers of boards at lower currents to take advantage of these efficiency gains, as well as provide better (more even) light coverage over their plants. Lower currents can also extend the life of the LEDs, as they run cooler.

Other growers prefer to run fewer boards at higher currents to take advantage of the high output of High Light boards (up to 225W each) whilst saving money on their initial outlay – possibly adding more boards when they expand their grow or reap the higher yields and reduced running costs of their LEDs.

Whatever current the boards run at, there is one golden rule: the higher the current, the higher the voltage requirements. All LEDs work like this.

This is the reason we suggest both 48V and 54V drivers for our boards.

High Lights will draw 48V at lower currents – typically around 2.5A for a total power consumption of around 120W (48v x 2.5A = 120W).

But at higher currents, the boards will draw higher voltages – up to 50V at their maximum current of 4.5A (50V x 4.5A = 225W).

This is the tricky part: some 48V drivers, such as the Mean Well “A” and “AB” type, will supply more than 48V (higher than their rating) and can drive the LED boards all the way up to their maximum current.

Some 48V drivers – such as the Mean Well “B” type – are limited to 48V, so can only supply enough voltage to drive each board at up to 2.5A. The boards are now “voltage limited” – they cannot draw more current, because there is not enough voltage supply.

In the above example, using a 54V “B” type driver would fix this, as there is now enough voltage to allow the boards to draw their full current. However, a 54V driver will supply a lower current than a 48V driver for the same wattage (example: 48V x 4.17A = 200W; 54V x 3.7A = 200W), so the boards may end up being “current limited” instead of voltage limited (enough voltage, but not enough current).

To further confuse matters, drivers run more efficiently the harder you run them (the complete opposite of LEDs), so it pays to match your driver to your intended wattage.

It’s this balancing act between voltage, current and efficiency that determines how many watts an LED draws, and how much light it gives off.

But if you are still confused about which driver to buy, then we are here to help. Simply Contact Us and we will suggest the best driver based on your grow area, budget and lighting requirements.

And if you’re wondering what the other differences are between the “A”, “AB” and “B” type Mean Well drivers, please read on . . .

Constant Current vs Constant Voltage

All Mean Well drivers are constant current drivers. This means when you set the current it stays there – and the driver automatically adjusts the voltage.

Voltage will fall as the LEDs heat up and rise as the LEDs cool down – until they reach a state of equilibrium, where the current, voltage and temperature balance out.

Mean Well “B” type drivers have an extra wire that can be connected to an external potentiometer or dimmer that can be used to adjust the current up and down. If the dimmer wire is not connected, the driver will output its full current at all times.

A Mean Well “B” type constant current driver. Note the two wires on the right: the top wire is the DC output to the LED board, the bottom is the dimmer wire that goes to a potentiometer to control the current. The wire on the left is the AC input wire that usually has a mains plug on it.

Mean Well “A” and “AB” type drivers are referred to as “constant voltage” drivers – even though (confusingly) they are really constant current drivers. Both drivers have a screwdriver adjustment dial under a waterproof rubber cap for both current (Io. ADJ) and voltage (Vo. ADJ).

Most times you will adjust the current dial and the driver will act in constant current mode, limiting the amount of current (amps) to the LEDs, and adjusting the voltage automatically.

But by setting the voltage dial, you can also “voltage limit” the LEDs, which restricts them to only drawing as much current as the voltage limit allows (no matter where the current dial is set) – the driver is now working in constant voltage mode.

The “A” type drivers can only be adjusted with a small screwdriver that turns the Vo and Io dials after removing the rubber caps.

The “AB” type driver adds a dimmer wire so that you can adjust both the voltage and current on the driver (with a screwdriver) or the current with an external potentiometer or dimmer.

A Mean Well “A” type constant voltage driver. Note the lack of dimmer wire and two adjustment dials under the black caps on the bottom right of the driver: one for voltage (Vo) on the left, and the other for current (Io) on the right.

Apart from being able to adjust the voltage, “A” and “AB” type drivers have another advantage over “B” type drivers – they always supply more than their rated voltage (up to 53V for some 48V “A” and “AB” drivers), while supplying more current than a higher voltage-rated “B” type driver.

Some growers prefer “A” type drivers with onboard dimming, whilst others prefer “AB” type drivers with the option of an external dimmer.

How to adjust your driver

Unless you have a multimeter or two and are proficient at using them, the easiest way to set up a driver is to buy a cheap watt or power meter (also known as a wall or plug meter) from your local hardware, electronics or consumer goods store and plug it into the mains. Then, plug your driver in and read off the meter.

Most of the Mean Well range of drivers we sell run at 93-95% efficiency. This means when you plug the driver in, 5-7% of the total wattage is being consumed by the driver, and the other 93-95% is being consumed by the LED boards.

A quick example would be a wall reading of 210w – 200W (95%) is going to the LEDs and 10W (5%) is going to the driver.

Unlike LEDs, drivers run more efficiently the harder you run them – so it pays to select a driver that will run close to the desired LED wattage at the driver’s maximum output.

Step 1
Turn the voltage dial (Vo) all the way up (clockwise), and the current dial (Io) all the way down (anti-clockwise).

Step 2
Make sure the driver is connected to the LEDs. Plug the driver into the wall meter and turn on the mains.

Step 3
Note the wall meter reading: as you turn the current up, the wattage will increase until you get to your desired wattage. However, as the LEDs warm up, the wattage will start to decrease.

Step 4
Allow the LEDs to run for 30 minutes to warm up and then re-adjust the driver to your preferred wattage (don’t forget to add 5-10% for the driver).

Step 5
You may now choose to voltage limit your LEDs by slowly turning the voltage dial down until just before it starts to reduce the power at the wall meter. Limiting the voltage in this way will ensure that if, for example, you have multiple boards wired up in parallel and one or more boards become accidentally disconnected, the remaining boards will not draw all the current and potentially burn out, because the driver will kick into constant voltage mode.