Description
A comparison of two BT-15 light bulbs - a Feit Electric 60w halogen and a Satco 8w (60w "equivalent") LED.
I vividly remember seeing BT-15 shape bulbs for sale during the 2000s, but only for a brief period of time. When I started collecting light bulbs more seriously, I was on the lookout for that shape again but didn't come up with much as I didn't know what it was called. After so many years, a BT-15 bulb surfaced at the thrift store at random, the Fiet Electric 60w halogen shown here. Unfortunately I have no specifications on it has it didn't come with the box and I can't find any trace of it's existence on the Internet.
The shape holds no practical application to me, I just find it interesting as it reminds me of the old mercury vapor bulbs. Of course incandescent BT-15 bulbs are no longer under production at this point, but there are still some LED models available. I seldom have good results with LED, but figured I'd give this model of Satco bulb a try.
I was pleasantly surprised with these when i first got them, and I'm even more pleasantly surprised with them after seeing it side by side to the halogen. The two bulbs are nearly indistinguishable. I do not detect any flicker, glare, harshness, or other unwanted phenomenons from these bulbs. Perhaps best of all, I haven't gotten a headache from long-term exposure, which is what I usually experience with LED lights.
The color of the bulb, the color of the light, the color rendering, and the optics are a nearly identical match to the halogen bulb. Unless looking particularly closely at the shape of the filament, I don't think you'd be able to tell the difference between these two, especially not from behind a lamp shade. I am absolutely astonished at how good these bulbs are.
The only area where they fail is the dimming. The LED bulb dims properly in the sense that it gets dimmer evenly, but it doesn't match the aesthetic of the halogen on the way down. Incandescent bulbs get warmer as they dim, but the LED remains the same color temperature. This is a deal-breaker for me in applications where the light needs to be dimmed, but for where dimming isn't applicable, these are excellent.
The specifications as measured during the video for each bulb:
Satco LED:
Brightness - 590 lux.
Power - 6.7 watts.
Efficiency - 88 lux/watt.
Feit Electric halogen:
Brightness - 338 lux.
Power - 63.4 watts.
Efficiency - 5.3 lux/watt.