RE: LEDs.
1. They are not that much more efficient. Somewhere between a halogen and a flourescent light. Maybe 2x as efficient as an incandescent?
2. Total light output is measured in Lumens. Most household light bulbs will have this rating, and some work lamps will. A 60 watt incandescent bulb might be 800 lumens (if I remember right) look on household light bulb package.
A lot of LED lights are only rated by their peak intensity in candelas "cd" (or milli-candelas "mcd" for the old whimpy ones). While Lumens measure the total light output in all directions, candelas measures the intensity of light per unit solid angle, or how intense it looks when viewed from a specific point. Most LED lights only quote the peak intensity. Sometimes, they also quote the angle of coverage. If not, it probably falls off from the peak to nearly zero over a 30 degree cone or so. Some LEDs are 15 degree angle, and others might be as small as 5 degree angle. To convert from candelas to lumens, you have to integrate the intensity over the solid angle (in steradians) - a good calculus exercise.
Intensity is good for rating things like tail-lights and stop signs wher you need to know how bright the lamp will appear when shining directly into the viewers eyes. Intensity is also OK for estimating the performance of spotlights given comparable angles of coverage. Lumens is better for comparing the total amount of light to illuminate a large area.
An easier way to estimate total light output is to go by the number of watts input (Voltage x Amps) and compare to a known lamp like a 60 watt bulb. Based on its efficiency, an LED may produce 2x the visible light for the same power input.
3. Although the LED itself may last for 20,000 to 100,000 hours before it gradually fades to half its light output, there are lots of other things in a lamp assembly that can fail. Properly mounted, potted, and connected with corrosion-proof connectors, they will be very durable. Poorly soldered to a cheap circuit board, corrosion and vibration can still cause failures of the lamp assembly.
4. I like the idea of an LED lighting bar on the ROPS, but I suspect a bright enough one may just be too expensive for quite a while.
- Rick
1. They are not that much more efficient. Somewhere between a halogen and a flourescent light. Maybe 2x as efficient as an incandescent?
2. Total light output is measured in Lumens. Most household light bulbs will have this rating, and some work lamps will. A 60 watt incandescent bulb might be 800 lumens (if I remember right) look on household light bulb package.
A lot of LED lights are only rated by their peak intensity in candelas "cd" (or milli-candelas "mcd" for the old whimpy ones). While Lumens measure the total light output in all directions, candelas measures the intensity of light per unit solid angle, or how intense it looks when viewed from a specific point. Most LED lights only quote the peak intensity. Sometimes, they also quote the angle of coverage. If not, it probably falls off from the peak to nearly zero over a 30 degree cone or so. Some LEDs are 15 degree angle, and others might be as small as 5 degree angle. To convert from candelas to lumens, you have to integrate the intensity over the solid angle (in steradians) - a good calculus exercise.
Intensity is good for rating things like tail-lights and stop signs wher you need to know how bright the lamp will appear when shining directly into the viewers eyes. Intensity is also OK for estimating the performance of spotlights given comparable angles of coverage. Lumens is better for comparing the total amount of light to illuminate a large area.
An easier way to estimate total light output is to go by the number of watts input (Voltage x Amps) and compare to a known lamp like a 60 watt bulb. Based on its efficiency, an LED may produce 2x the visible light for the same power input.
3. Although the LED itself may last for 20,000 to 100,000 hours before it gradually fades to half its light output, there are lots of other things in a lamp assembly that can fail. Properly mounted, potted, and connected with corrosion-proof connectors, they will be very durable. Poorly soldered to a cheap circuit board, corrosion and vibration can still cause failures of the lamp assembly.
4. I like the idea of an LED lighting bar on the ROPS, but I suspect a bright enough one may just be too expensive for quite a while.
- Rick
