Over-driving fluorescent lights

[angelstiger]

I just finished overdriving my 4' flourescent shop lights. If you have a little electrical knowhow, this is a way you can get 80% more light from your flourescents. If anyone is interested, I can post a few links that will give the information you need to do it. i will also be happy to answer any questions if I can.

[angelstiger]

Just need a better ballast for the $10 HD cheapo shoplights right?

Yeah, Basically you run 2 bulbs with a 4 bulb ballast. I bought 3 electronic 4 bulb ballasts on Ebay for $20 including shipping. So with doubling up the 2 bulb ballasts that came in the shop lights, I have 6 extremely bright lights for about $80.

[geol]

The "High power factor" ballasts popular with aquarium enthusiasts and others are much more expensive.
Overdriving produces a high power factor using cheap electronic ballasts.
http://www.geocities.com/overdrive_lights/

[Mischka]

I'm going to give this a shot with my fluorescent fixtures - thanks for the information.

I bought 2 metal halide units last year from Worms' Way - good way to make my electric company wealthier!

Does anyone here use High Pressure Sodium lighting to start seedlings?

[tjg911]

charlie,

what is the purpose of overdriving? i read about this at the gul forum at gw 2 years ago but i forget. does this draw more juice, increase amp use on a breaker and cost more for extra electricity used? cost is pretty minor presently but i am concerned about amps being used on my present setup, i have a fridge (requires 15 amps) and 4 lights using 256 watts on a 20 amp breaker. i want to add more shop lights, another 384 watts. i may start a thread on this.

the reason i ask is that i get great results using shop lights from hd. i can't imagine any better results, i actually have delayed my seed starting from 4/1 to 4/10 cuz my plants were so tall by 5/15 they barely fit under the lights. i twice changed the height of the shelves for the extra growth. from what i remember if your plants, any plants, get too big (tall) the upper leaves are getting the light while the lower foliage gets very little. this is why you can't grow 3'+ plants under fluro lights and you have to go to metal halide which as mischka noted are expensive to run (and buy).

why did you overdrive them?

tom

[geol]

"what is the purpose of overdriving?" -

Like you said - you can only fit so many plants under one fixture. After that, in order to get more light on them, you need a higher output fixture.
Although readily availible, these ballasts are much more expensive.
2Xoverdriving produces a higher power factor using cheap electronic ballasts. (reportedly 70% more light).

The link I posted above, (Tue feb 21), I think will take you to the thread you mentioned. There is also a 2nd thread w/same title + cont... if you want more info.

I did this with two of my fixtures, and while I don't have the equip. to verify a 1.7 times increase in output, I can say they are brighter.

I bought another fixture ($7.98) with the intention of doing the same thing, but have decided to use it as is, for other considerations (100% more light vs 70%, and twice the flexibility for other uses, as I can better use an additional fixture than to make the one I already have brighter).
As you also mentioned, with proper care and attention, standard fixtures produce good results.

I should also note that while using a product in a manner other than intended by the manufacturer may still be well within the design spec. of the components, the user assumes any risks by making modifications.

Link to VHO high output flurescent lighting:

http://www.marinedepot.com/aquarium_...dex.asp?CartId

[angelstiger]

Why have I overdriven my lights? Because I feel the more light the better. Producing stronger, healthier, stockier seedlings. I admittedly have never had a problem growing my seedlings with normal shop lights. Maybe I did it for the Frankenstein factor, LOL.


As far as the science of it, I am no expert. But as I understand it, 2 overdriven bulbs actually draw less amperage than do 4 normal bulbs. I will clip and paste a few quotes from Zink, the guru in the above link.

As far as wattage goes, I have measured the power consumption while 2x overdriving both 32w and 40w lamps. I measured the power in amps, but converted it to watts here:

Normal (Not Overdriven) 1x
F32T8..... 32.3 watts
F40T12... 29.3 watts

Overdriven 2x
F32T8..... 54.9 watts
F40T12... 51.9 watts

These measurements are per 1 bulb. The brand of lamp is insignificant. The line conditions and the brand of electronic ballast used will alter the readings, but not by much. I have tried other ballasts and got about the same numbers. Notice that the electronic ballast does not double the power consumed. The more times a bulb is overdriven, the less efficient it becomes, as it is starting to drift out of the bulbs optimal design parameters. A 2-bulb fixture, then, would consume 104 watts total. The old magnetic ballasts with F40T12 bulbs consumed about that much per fixture!

It really was like paralleling two batteries to double the available current. If you wire a bunch of auto headlamps to a stand-alone 12v car battery, they will light and begin to draw current. If you parallel the battery with another, the headlamps will brighten AND the current load on both batteries becomes less. That is the best analogy I can come up with. Also, the 2x overdriven ballast actually draws less current (verified by measurement) than if it were lighting two bulbs, instead of one overdriven one.

As far as you circuit overload problem, the amperage used by florescent lighting is measured in milliamps (mA).

A NORMAL electronic ballast with 2 lamps(32wT8) uses about 530 mA of line current [63.6w]
An OVERDRIVEN electronic ballast with 1 lamp(32wT8) uses about 460 mA of line current [55.2w]
The two individual lamp circuits inside the ballast are sharing the lamp load

In other words each of your normal 2-bulb shop lights are drawing about a half an amp. I run my 4 overdriven shop lights on the same circuit as my chest freezer, which is on a 20-amp circuit, and have had no problems. I am not an electrician, but as long as you have 12-gauge wire in the circuit I wouldn't worry about it unless it starts tripping out. If it does start to trip out, 12-gauge wiring can handle a 20-amp circuit breaker. Your idea of tapping into the lighting circuit might be a great idea though, as lighting circuits don't have the huge draws that are on circuits containing appliances. A warning note though, lighting circuits are often wired with 14-gauge and shouldn't be any higher than 15-amps.

I am no expert, as I said above. All that I have said here is just knowledge I have picked up being a homeowner. It is always best to contact a licensed electrician with any questions regarding you household wiring. Better safe that sorry, or even dead.

[gflynn]

Mischka

I use a 425 watt HPS bulb. My brother used a 1000 watt MH but it seems to burn the plants even when it is on a moving track and sitting 4 feet above the plants! I rarely have this problem with my stationary light. I think MH may be harsher light.

I have been pretty happy with my light and it covers a 3 foot square area pretty well.

Greg

[Mischka]

Thanks for the info, Greg.

Another good reason to use HPS over MH...I'd hate to cook my seedlings. Yikes!

The light also seemed to hurt my eyes after working under it for a while. I wonder if MH gives off damaging shortwave UV rays?

I'm going to look for some decent ballasts and attempt to overdrive my existing fluorescent light setup.

[gflynn]

Mischka,

I have often wondered about hardening off with MH lights. With HPS my plants still get a sunburn when I put them out in direct sunlight. Is it any better with MH lights?

Greg

[Mischka]

I've avoided getting sunburn on my seedlings for the last few years, but I don't think it matters which type of artificial lighting I use to start them.

The key is making sure that their exposure to the sun is done gradually. I let them get about 30 minutes of direct outdoor sunlight for the first couple of days. I use a cooking timer; when it beeps I waste no time getting them out of the sun. I've learned the hard way that too much sun too soon = sunburnt whitish leaves.

I put them back under artificial light after each dose of the real deal. At the end of week 1, mine are in direct outdoor sunlight for 2 hours a day. I increase exposure time in larger increments during the second week.

At the end of two weeks, they are exposed to 6 hours of direct sunlight and are fully hardened off.

[gflynn]

Mischka,

Sounds good buy I usually start my plants so early that they are kinda big to move by the time I am ready to harden off. I need a table with wheels on my deck!

Keith says that he just puts them on the north side of his house for half a week completely out of the sun then gradually puts them in direct sun.

I am going to homedepot to get some wheels!

Greg

[eclectusuk]

Oh and I have just put the seedlings under 60 watt of compact fluros in desklamps on the window sill..

Can I give the tomato seedlings (Tigerella, Marmande, Costoluto, MM, Money Maker, GD and F1 Tumbler) 24/7 of this light?

Also could the wilting first feed leaves be that the compost was for seeds and may need some nutes now?

e

[dcarch]

A question was asked of me in another thread, “ What is a over-driven fixture?”
I decide to answer it here, since it is not really about seed starting.

I am sure you all have felt the frustration of the last few weeks of the season with the huge harvest of unripe green tomatoes.

One way to gain great advantage when your plants are at their most productive is to start as early as possible and have plant as big as possible to transplant in ground.

You can custom rewire fluorescent fixtures with electronic ballasts to produce much higher light output. This is called over-driving.

Normal fluorescent bulbs are made to run efficiently with typical e. ballasts with a life span at about 20,000 hours. If you over-drive the bulbs they will run less efficiently and with shorter life; however you will get much more light output. With bulbs so cheap, it is not a concern to run them at a shorter life.

Higher light output will allow you to start seeds earlier and grow seedlings taller before you transplant in ground. The payback is great.

Re-wiring ballasts is not difficult, however, you are dealing with power electrical devices, you should have some experience in doing this.

Attached is a typical wiring diagram for over-driving fluorescent lights.

[TomatoDon]

I have a lighted seedling table, per Suze's help, and I keep it by large windows that face the southwest, getting afternoon sun in the late winter (February-March) of about 4-5 hours as the daylight hours increase. I wondered last year how much effect this had on my seedlings and if the natural light was enough for the seedlings. I ran the lights at least 12 hours a day. And I also saw some examples here of people using their window sills and natural light and getting fine results from their seedling operation. I'm guess with the supplemental natural lighting I have that I wouldn't need to over-drive the lighting fixtures.

Don