QUOTE=blah9;3653569]Also, isn't it true that for some flashlights' low modes, the LED actually runs at full brightness but is switched on and off repeatedly to make it put out less light? That would mean that on a lower mode the light is being switched continuously instead of just staying in one state.[/QUOTE]
This is what is called Pulse Width Modulation (PWM), and lots of manufacturers use this principle to vary the light intensity. The LED is powered at max, but intermittently, at high frequency so we don't really see it flicker, to make it look dimmer. This same principle is also used in a variety of applications, including electric motors. I am planning a thread to explain PWM a little better and how to detect it.
LED's will not be affected by coming on at full power (provided you respect the battery recommendations for the specific light). In fact most lights do not "ramp up" gradually between outputs, but just switch suddenly to the next output (sometimes going off very briefly between modes), so starting with a lower output and switching to a higher one will often have the same effect as turning the light on in full-blast: all the power goes to the LED suddenly. Some -if not most- manufacturers do program their regulators to be more gradual, a little like a soft-start switch, or at least make sure the driver will not exceed the LED's maximum voltage/current at power on, which certainly helps in the long run.
"Ramping up" an Incan bulb is not necessarily a good idea (not talking about soft-start switches, here, but it could apply in some cases). That depends on the construction of the bulb. Some bulbs will burn out faster if you give them less than a certain amount of juice. Some bulbs will last longer when not used at their maximum. Some other bulbs won't care either way and burn out after X hours. The specifics include too many factors and these definitely surpass my knowledge of bulbs. Most flashlight bulbs will work fine for a long time with depleting batteries, since it is expected that your batteries will not give the same output all the time.
The two biggest factors that shorten the lifetime of electronics or mechanical devices:
- Heat, generated from either extended usage, running at fulls power, hot environments or lack of ventilation, etc.
- Start / stop. Yep, turning things on and off frequently is not good for them, but LED's can handle quite a bit, so don't worry about using your flashlights for morse code. The start/stop factor affects bigger machines and high power electronics much more than small equipment... your LED light will last a long time even in strobe mode...
With incan soft start can be beneficial because a cold bulb will draw much extra current, until it heats up.
Led does not have this, the driver always feeds them a constant current. The led will only take damage if it gets to hot and that does not happen at power on, but after some time. With a direct drive led you might damage it when starting on fresh batteries, because the current can be above the maximum rating for the led.
Great way to put it!
