Digital Ballasts Vs. Magnetic Ballasts
Using a magnetic ballast? It could be time to upgrade.
Magnetic ballasts may be cheaper to buy, but digital ballasts cost less overall.
What's a Ballast?
Each lighting system is made up of a reflector, grow lamp and a ballast.
It’s your ballast’s job to regulate how much power goes to your lamp:
Try using a grow lamp without a ballast and it won’t be pretty. If you’re lucky, your lamp won’t light. What’s more likely, is that your lamp will explode.
There are two kinds of ballast you can use - Magnetic & Digital.
These use what’s known as a ‘choke’ to regulate power output.
A choke is a steel core with a metal wire coiling around it.
- The steel core is often laminated steel plates
- The wire coil is often copper or aluminium
Together, the core and coil create an electromagnetic field that regulates the output voltage.
These use solid state circuitry to transform and regulate the power output to the lamp.
They’re much smaller, lighter and efficient than magnetic ballasts.
In this day and age, most people are using them.
Which Ballast is Best?
The ballasts are very different. But which one's best? Digital all the way! Here's why.
1. Size and Weight
This one's easy.
- Magnetic Ballasts: Are big, bulky and heavy
- Digital Ballasts (or electronic ballasts): Are small and light
If you're struggling for space, you'll find it easier to get a small, digital ballast in.
If you're mounting it with your reflector, as a complete fixture, digital ballasts are lighter, too.
2. Energy Saving
Digital ballasts are waaaaay more efficient.
It’ll vary, depending on which units you compare, but typically digital ballasts use 3 - 4% less energy.
This doesn’t sound like much but, when you’ve got multiple grow lights on the go, the combined saving really cuts down your energy bills.
3. Heat Output
Magnetic ballasts produce a lot more heat. The flow of electricity through the choke’s core and coil sees to that.
All of that heat is an unwanted by-product – evidence of how inefficient magnetic ballasts are.
Digital ballasts also generate a little heat, but not much compared to magnetic ballasts. Internal parts are actually sheathed in plastic to help prevent heat problems.
The coils in magnetic ballasts vibrate, which creates a soft humming noise. This humming gets louder and louder as the ballasts age and the coils become looser. The loosening of coils also makes them slightly less efficient.
If you want to run a quiet grow room, always choose a digital ballast. They run silently, with no humming and no buzzing whatsoever!
5. Light Consistency
Magnetic ballasts can only output the voltage that goes in – no more, no less.
This is a BIG problem, because the output from a standard UK mains electrical supply ranges from 220-258V, depending on your location.
Magnetic ballasts operate well at 230-240V...
- Lower than this and they’ll underperform
- Higher than this and they’ll use more energy
To complicate matters further, voltage from your mains supply can fluctuate by 10-15V depending on:
- The time of day (due to the demand on the grid)
- The amount of electricity you are drawing on a circuit at your property
Every time you add an extra magnetic ballast to the electrical circuit that powers your grow room, the voltage reduces. This decreases the light output of all your lights!
A variation in the mains voltage means a variation in electrical consumption and light output. Ultimately, this can harm plant growth and lower your yield.
You won’t get any of this with a digital ballast. They have the ability to transform the incoming voltage up or down, regardless of the supply.
6. Frequency of Lighting
Magnetic ballasts are governed by the frequency it gets from the main supply (around 50Hz).
Basically, this means it’ll go on and off 50 times per second. That’s a fairly low frequency that creates a ‘flickering’ sensation. Digital cameras actually capture the banding effect it creates.
Digital ballasts regulate the output frequency. You’re looking at a frequency of 40,000-100,000 Hz, depending on the brand and model.
This excites the gases in the lamp more efficiently. Overall you’ll have a better light output, a longer lamp life and more accurate colour rendering.
7. Dimmable Lighting
Digital ballasts can be dimmed. Magnetic ballasts can’t.
Why dim lights?
1. In early veg, plants are still very delicate. A light that’s too intense can stress and shock them. To prevent this, start off on a dim setting then slowly increase your intensity to ease plants in.
2. To control your temperature you can lower your light intensity. This'll happen automatically if you have one or more Parlux Linx 600W Temperature Controlled Ballast hooked up to a Parlux Master Controller.
8. Overdrive function
With a dimmable digital ballast, you can overdrive your output by 10%. This means you can give your plants the extra push they need for bigger yields.
A 600W lamp can emit 660W for a short period of time. Doing this does reduce your lamps life so use sparingly.
Don’t ever overdrive a Metal Halide lamp – they won’t be able to take the output.
Magnetic ballasts are cheaper to buy, but cost way more to run and are slightly quicker to degrade.
For optimum efficiency, you should replace your magnetic ballast every 2-3 years.
Digital ballasts last much longer, and have a consistent output over their life. They only need replacing if they stop working, which can be 10+ years.
When you break it down, and take running costs into account, it costs less to run a digital ballast.
10. Digital vs. 400V
The icing on the cake with digital ballasts is 400V lighting - typically offered by commercial greenhouse systems from the likes of Gavita.
400V ballasts take 230-240V (delivered by the mains electrical supply in your house) and transform it up to 400V. Why? It’s all about the lamps.
The short of it is: 400V lamps produce more plant usable light (micromoles) than standard 230V lamps (more on micromoles here).
The average increase with 400V lamps is 8% more light, which produces better growth and on average 10% higher yields compared to 230V!
11. Connects to controller
Some of the newer digital ballasts can connect to controllers (like the Parlux Linx models). Magnetic ballasts can't.
For a long time now, greenhouse lights (like Gavita e-series) have been using external controllers to micromanage their light settings. But now more affordable options can do it too - like Parlux. It depends on which one you have, but typically, using a controller you can:
Dim & boost in tighter increments
(10W for Gavita, 2W for Parlux)
Use sunrise & sunset mode
Slowly dim & boost lights over a period of time when lights turn on and off. This is so you don't shock plants, and you prevent condensation forming on fruit and flowers during bloom - this helps prevent bud rot.
Temperature control over lighting
You can set lights to dim and boost at set temperatures to keep your grow room climate spot on.
Those are just some of the features you'll get access to when you use a digital ballast with a grow light controller. Some controllers allow you to connect external devices - like extractor fans, heaters & CO2 equipment. Some allow you to manage grow lights in multiple rooms, each with their own light cycle. Overall a grow light controller makes it much easier to manage your grow room.
Which ballast should you use? It’s a no-brainer really – digital ballasts all the way!
Benefits Of A Magnetic Ballast:
- Cheaper to buy
Benefits Of A Digital Ballasts:
- Cheaper to run (uses less electricity)
- Lightweight and compact
- Consistent, high light output
- Overdrive function – intensify your lights
- Longer life
- Can be used with a controller
Just for good measures, here's a comparison table
|Size and Weight