Digital Ballast

Is it worth the extra money to buy a digital ballast or are the regular lights, like on Hi-Tech Garden supply good enough? Thanks for any input.

The digital ballast is better. How much 'extra money' are you talking about? The savings would come from long term use of the digital ballast. 'Good enough' depends on long term use. Your ball. VV

hI VV. The regular 400 watt is $120 and the digital ballast is $240..double. I was just reading about the digital being quieter and cooler. I guess it's a money issue...thanks

Thanks BloodshotI'z, I think I'll get that one then. Do you have any problems with high temps now with the ballast out of the room? If so, what size room and fan do you have?

When I first put the light in...yeah the temps shot up to about 90f. But I only had one oscilating fan at the time. I bought two more fans from Walmart for $13 each. Since Im in a closet I put on on the top shelf and cracked the door...then put the other on the floor and cracked the other door. Now my temps are about 80-82f.....under the lights.

Pix in gallery of growroom size. Fans are "Hometrend" metal caged fans.

the digi ballast will also help save you some electricity

Digital Ballasts
The days of the old humming, magnetic core & coil-type ballasts may soon be coming to an end. The digital (electronic) ballast is the latest in ballast innovation. Digital ballasts are more efficient, quieter, cooler, and softer on the bulb. Digital ballasts do not have any of the usual transformers, capacitors or igniters; instead these ballasts have electronic circuitry to do the same job, more efficiently. What might take a standard coil/magnetic ballast 680-700 watts to fire a standard 600 watt bulb, may only take a digital ballast only 600-620 watts to fire the same bulb to the same brightness. The old coil type ballasts are hard starting ballasts; when the ballast fires the bulb it sends full power to the cold bulb. Over time, this shortens the bulb life and reduces the PAR output of the bulb. Digital ballasts start by sending a low amount of power to the bulb and steadily increases the power over the next few minutes until the bulb has reached full brightness. This is also known as soft starting, which minimizes the damage to the bulb and increases its PAR life (PAR represents the plant usable light; it’s what plants “see” and use, versus lumens which are what people see). After one year of use the plant usable light coming from bulbs that are run on digital ballasts has decreased only by 20-25% where as the same bulb being used in the coil type ballast would have lost 50-60% of its plant usable light over the same period of time.

Coil type ballasts are also known to cause the bulb to flicker or strobe. This takes place so quickly that the neither human eye nor light meter can pick it up. Digital ballasts provide a uniform power supply to the bulb, thus eliminating the flickering from the bulb.

Digital ballasts are great stuff, but they are still new-ish and very expensive compared to inductive (magnetic) ballasts. The payback time, if based only on power cost, would be very significantly longer than the service life of the ballast.

That by no means should be taken to mean 'don't buy digital ballasts.' They will extend the life of HID lamps, not by a lot, but by a bit. Again, not enough to recover the extra cost of the digital type in a reasonable period, but it is a savings.

I believe the real advantage of the digital ballast is the fact that the lamp from a 600 digi will come very close to rivalling the amount of light emitted from a lamp fired with a 1000 watt magnetic coil ballast. (reportedly the 600 puts out 10% less light than the 1000)

We shall see. I have 4- 600 watt Lumateks on hand to slap into a new room...soon to be constructed!

*IF* the light output is greater as claimed, the yield generated by the extra light output should have a significant payback in itself.

like I say...we'll see.

good luck

bt dt

beenthere donethat said:

I believe the real advantage of the digital ballast is the fact that the lamp from a 600 digi will come very close to rivalling the amount of light emitted from a lamp fired with a 1000 watt magnetic coil ballast. (reportedly the 600 puts out 10% less light than the 1000)

[...]

*IF* the light output is greater as claimed, the yield generated by the extra light output should have a significant payback in itself.

Click to expand...

Now, hang on... what ballast maker is making those claims?

All a digital ballast does is manage the current to the lamp, just like a magnetic does. Warms up the lamp, strikes the arc then cuts the current down. Digitals just do the startup a bit more precisely than magnetics. However, there's no difference in the current supplied to the lamp while running.

The performance of a lamp connected to a digital will be no different except for more starts per lamp life on a digital. The digital ballast will also consume less electricity while running, absent eddy current heat losses produced by the transformer in magnetic ballasts- but not THAT much less.

The average 600 HPS puts out about 90,000 lumens. A 1000 puts out 160,000. That's a bit more than a 10% difference.

Digital ballasts simply can't increase the light output of a tube compared to magnetics, only soften the startup currents to the lamp.

Any ballast seller making claims of greater light output of digitals over magnetics needs to revisit their basic electronics- and make their claims to suit the facts.

here ya go Lumatek - Homepage

Wow..3 posts in a row eaten by the system...

Al... I'd like to hear what the folks at Lumatek say when you clue 'em in and show em that your tests on these digitals showed much different results than their own data has shown.

please copy the posts you receive from 'em in return when you write 'em. I can still take these junkers back at this point if they are lying out their ass...

good luck

bt dt

Thanks for that. I'm going to pop them a note and ask how they're getting 30% more lumens out of the same lamp. I hope to get some reasonable electronic explanation and not "it's proprietary information."

I'd like to see an independent confirmation of the Lumitek claim. Anyone with an HID lamp, a Lumitek ballast, a comparable magnetic ballast and a light meter can do it.

beenthere donethat said:

Al... I'd like to hear what the folks at Lumatek say when you clue 'em in and show em that your tests on these digitals showed much different results than their own data has shown.

Click to expand...

As I don't have a Lumitek ballast and acquiring one is no small amount of change, I'm really hoping for someone on here who has access to one (and hopefully an owner, not a Lumitek or hydro shop rep) to do a quick test. The claim is 30% greater brightness out of the same HPS tube.

The Lumitek claim seems improbable when you consider the way an HPS makes light. Unless there's something really wacky about the frequency of the current applied by the Lumitek ballast to the tube which causes the tube to emit light MUCH more efficiently than does a magnetic at standard line frequency, increasing the luminous output by 30% will also increase the heat dissipation in the tube by some similar figure. The tube will be designed to dissipate heat at a certain rate; raising the heat output beyond that would seem to exceed the thermal limits of the tube components.

I've sent a query to Lumatek. Asked if their testing was done by an independent lab and if I could get a copy of that test data. Also asked what the 30% greater luminous output does to the heat dissipation in the HPS tube.

beenthere donethat said:

I can still take these junkers back at this point if they are lying out their ass...

Click to expand...

Now hang on- I wouldn't call them junkers.

Digital ballasts DO have some definite advantages over magnetics- I just don't think they have all the benefits claimed by this maker.

Now, this much proves nothing- but Lumatek are the only digital ballast maker I have been able find from Googling which make a claim of increased luminous output.

Lumatek either have discovered something novel that other makers (including giants like GE, Sylvania, etc) haven't uncovered despite their multinational sized R&D budgets- or the Lumatek claims are suspect.

Either way, the Lumatek product looks well made and will surely increase tube life. I'm not so sure about the brightness thing.

And BTW, when the prices of digital ballasts drop to within about 20% of the price of magnetics, I will be in queue with cash in hand.

I AM a fan of what I electronically know digital ballasts can do. The greater claims, while nice if true, are not anything I am expecting from a digital.

One other thing about these digital ballasts is that are reported to run both MH and HPS lights, so no need for 2 ballasts.

Another plus, digital ballasts are effectively pulse-width modulated (PWM) power supplies.

Computers have PWM or "switching" power supplies. They would waste 3-4x more power in simply converting from line AC and regulating the DC voltages needed by the PC if they had linear, transformer based power supplies instead of PWM type. PWMs are about 60% more efficient than transformer & linear regulator types; I would expect the same efficiency improvement from a digital ballast.

PWMs still supply a voltage at a certain level but in PWM AC supplies, have the advantage of manipulating the waveform and frequency. They're also often supply-voltage agile, meaning they can run on 120v or 240v with only a change of line cord.

However, Ohm's Law still rules the HPS tube. When it's up to temp, an arc strikes in the mercury/sodium amalgam vapour. That arc path has a certain resistance and a certain current is being applied across it. Current (squared) * Resistance = watts (as heat). It's the arc through the vapour creating the light. I can't see how Lumatek is getting more brightness without running more watts through the tube.