I looked through past threads but didn't see mention of this issue.
I have multiple 4' fluorescent light fixtures in my basement. I had standard T8, 32 watt flourescents in them, 2 tubes per fixture. I finally ran out of the old tubes, and I wanted to convert to LED. I bought what I think are the proper LED tube replacements--15 watts--that are supposed to work with the existing ballasts. They're GE LEDs rated at 6500K and 1600 lumens and are labeled to be direct replacements for what I had previously.
Well, 1600 lumens is pretty dim. A real T8 tube is about 2800-3000 lumens. Now, LEDs *can* make up for that with better **aiming** of the light. Most LED "fluorescents" only light up about a 160 degree arc, because they have all LEDs aiming the same direction, and that is the desirable trait obviously. A few LED "fluorescents" do the corn-cob routine and aim LEDs in every direction; that is almost always a mistake, it's rare to actually want a sphere of light.
However, aiming, as good as it is, doesn't make up for a 50% lumen loss.
Unfortunately that is the scam often seen with LED replacement bulbs: they say "it's a replacement" but it's actually *much dimmer*. Take a 38,000 lumen metal halide light, they'll proscribe a 16,000 lumen bulb to replace it, trouble is, it's a damn corn-cob, and so there's no aiming benefit. The fact is, discharge lighting (including fluorescent) is already quite efficient;
what the LED-sellers are really saying is "Save money by making do with less light."
*eyeroll*
Also, the LED sellers are comparing it to obsolete T12 lighting that is worn out. Fluorescents get somewhat dimmer with age, and T8 is efficient enough that some T12-T8 conversions were omitting the 4th tube and doing it with 3.
Does good aiming make a 1600lm LED brighter than a worn-out T12 down to 1900lm? Sure, I buy that. But your T8s were perfectly bright to begin with.
There's also ballast factor. T8 ballasts either underdrive or overdrive the tube, from 60% to 140% of power (0.60 to 1.40 ballast factor) - this is an aesthetic choice by the architect. Check out your ballast factor stated on the ballast - if it's low, perhaps the LED is excessively influenced by this. If the ballast factor is high, perhaps the LED is ignoring the ballast's attempt to brighten it.
The problem is that the light output is really weak and seems to produce less than half the light of my original tubes. Is this normal? Will they eventually get brighter if I leave them in for an extended period of time?
Yup, it's normal, and no, it really won't improve.
Worse, that 6500K color is Madly Frickin' Blue, and no doubt a real shocker/adjustment from the typical 4000K color of legacy fluorescents. The "bluer" LEDs are cheaper to make... and making the color "bluer" also makes the color *seem* "brighter" - even though that's not true at all. (of course real fluorescents are available in any color temp from 2700K to 6500K, so if you love the cloudy-day blue, you can get that in real fluorescent.)
I for one would only use 6500k in a transition-to-outdoors space, where people would be stepping out into a cloudy or sunny day. (sunny days are actually yellower than cloudy days, go figure).
Should I simply get stronger lights? Supposedly, my fixtures will also take T12s. This is my first experience with LED tubes, so I really don't know what to expect.
Your **fixtures** will take T12s. Your **ballast** will not. Your ballast will state which real fluorescent tubes it is compatible with. If you had flickering, slow starts, no starts, cloud racing, etc. going on in the tubes, I might have thought you had a T8/T12 mismatch. But I suspect you have a real electronic T8 ballast (which is Good Stuff).
My recommendation would be, given you've already got the ballasts, is take those hokey things back to the store, and go back to
Real Fluorescent bulbs, which are absolutely fantastic now. I'm all about Sylvania's Vivid Value Ecologic line, which has >90 CRI (excellent color rendering, better than most LED) and is available from 3500K to normal 4000K clear up to 6500K. I pay $2/tube at Menards buying multiple 12-packs.
Your new leds are getting into the blue white spectrum of light.
Yeah, they're really blue, and that would drive me bat crazy. That's bluer than daylight, that's cloudlight.
Wish I could help, too, but I have 14 in my shop and flipping the switch makes it look like a surgical suite. Really bright, and immediate.
Sounds like you have the right number of fixtures, then. I have places I am just unable to brighten, and the real bottom line is we need more fixtures in that location than are there. Having enough fixtures is 3/4 of the game!
I know my ballasts are good and specs match the LEDs. I did make sure to orient them properly with the LEDs facing downwards, too.
OK.
I think my ignorance of lighting specs and trust in the box copy confirms that many of you are right. Quite simply these don't produce as much light. Since I bought this house, I haven't had to pay much attention since it came with a good supply of tubes.
Oh, well, there's the problem. When I collect fixtures for free off Craigslist, one thing I do not want are the tubes. (I take them out of courtesy, beggars can't be choosers, but I don't need circa-2005 tubes that have 60 CRI with a tailwind). So yeah, J random leftover tubes, that's not gonna be awesome, that's how you get cruddy "old fluorescent" light. I want
bare minimum 90 CRI, and I can get those for $2/tube all day in T8 from tier 1 suppliers.
After checking into some of the data you've all given me, I'm going to find tubes with a lower K-rating and more lumens. If that doesn't work, I'll try bypassing the ballasts.
Aw, don't bypass the ballasts. Go for "universal" LED tubes (that work either in-ballast or direct-wire) until you find LEDs that you like. That way if you DON'T find LEDs that you like, you can walk back to some of those lovely 90 CRI real fluorescents,
that I guarantee you'll like.
New real fluorescent is a sure thing. It Just Works. LED "fluorescent replacements", as you are learning, is still struggling with issues.
