Lost a full stop intensity . . . hmmm.
OK, here's what I have observed while actually using them without the blocking diode that protects the voltage regulator:
First, I didn't give the amount of voltage drop coming from the 7812 regulators a lot of thought when I installed them. When I tested one against a fully-charged battery
I got a nice, 11.9-ish volts out the backside of the regulator. Though I knew there would be a voltage drop-off as the battery
ran down, I really didn't consider how severe that voltage drop-off wold be.
So here's what I observed when I first went out with my LED lighting
last summer, when I didn't need to run the furnace
in my trailer (only the fantastic fan) and the solar panel
kept up with my energy demands: I never noticed any drop in light
levels. The only time I have noticed a drop is when it's cold out and I'm running the electricity-hungry furnace
, and even then it isn't like I think I'm getting half the light
. By the time I need to use the lights
again the next day the solar panel
has generally charged my battery
back up to capacity again.
Since our eyes require a roughly 50% reduction in actual light
levels to create a perceivable difference in overall light, that fits with your observation that your light meter registers a full stop difference (a halving of the light) between the lights
under full power and when the battery runs down. You have to reduce lighting
levels by a factor of ten before most people will tell you they see half as much light; the same is true of your ears, you have to decrease sound intensity by a factor of ten before people perceive that the noise level has dropped by half.
Your mileage may vary, but this is a worthwhile trade-off when I contrast this small perceived drop in light levels against the simplicity of the circuit, its low cost, very low power draw, and the enormous importance of protecting my expensive LED lights
from LED-killing over-voltages. Sure, I could spend more money on a fancier DC power supply, but a fancier power supply would consume more energy, negating at least some of the reason I installed the LEDs in the first place. And, as I upgrade the other lights
in my trailer to LEDs and replace my forced-air furnace
with a zero-electric-draw catalytic heater, my overall current draw from the battery will drop way off, making the drop in light levels even lower.
So, yes, I can see why people would want to install the fancier power supply, but since I'm happy with the setup I've created, I don't see a whole lot of reason to change what I've got.