CREE TW Series tubes

Does anyone understand how these CREE TW tubes work?

http://www.homedepot.com/p/Cree-TW-Series-48-in-T8-32-Watt-Soft-White-2700K-Dimmable-Linear-LED-Light-Bulb-BT848-17027FLW-BDG13-1C100/205737568

They're marketed as direct replacements. No need to replace the ballast with an LED driver. I can't picture it unless there's some sort of electronic device inside the CREE tubes that converts the ballast output to something the LED tubes can utilize. That would mean energy lost at the original ballast, plus more energy lost converting it back to something else, wouldn't it?

At roughly 92 lm/watt they're not super efficient but that ain't bad.

That's a good point about the energy losses. Maybe that's why they don't seem to be catching on.

Your post gave me an idea. Why not affix SMD5730 strip LED to the channels of a flourescent fixture? 110-120 lm/w. Just use the LED fixture as the mounting surface and reflector.

Cree went cheap in the revision just like the household bulbs.....all about dat profit margin

Mello look at the Phillips insta fit t8 also sold at your local hd......110lm/w works on most insta/rapid start e ballast

PSUAGRO. said:

110lm/w works on most insta/rapid start e ballast

Click to expand...

But, doesn't his question still remain. I thought flouro ballasts created high voltage. There must be a conversion back to what the LED wants to see. Doesn't the ballast add an inefficiency?

I assume when they say 110lm/w that's the efficiency of the tube doing the single conversion. It doesn't take into account the efficiency of the fixture and its ballast?

I have tested both t5 and t8 led with a PAR meter. t5=40 @5" and t8=120@5"

az2000 said:

But, doesn't his question still remain. I thought flouro ballasts created high voltage. There must be a conversion back to what the LED wants to see. Doesn't the ballast add an inefficiency?

I assume when they say 110lm/w that's the efficiency of the tube doing the single conversion. It doesn't take into account the efficiency of the fixture and its ballast?

Click to expand...

Yes, correct.....as these new led tubes DON'T bypass the ballast.

The appeal of these is no relamping and using 13-18w instead of 32w floro t8.

What is the typical voltage/current output of a typical T8 ballast?

Thanks, Psuagro, I didn't know about the Philips. Dangit, the troffers in our kitchen are T12. I'd like to try a few of these out.

I don't know what's different between T12 and T8 aside from the physical size.

This article

http://www.designingwithleds.com/the-new-cree-tw-series-led-t8-review-and-teardown/

was very helpful and addresses some of the questions posted above.

But the article makes clear that your total efficiency is hobbled by the old ballast. No matter how efficient the LED tube you're still draggin' the anchor. That's it for me. If I was gonna convert a fluorescent fixture it'd have to be a total change-out to a modern driver/LED tube. No half-way measures.

You could probably sell the ballast from a 4foot shoplight on ebay for more money than the shoplight itself costs.