To really make the best usage of say an emergency
light is to use a dc/dc converter, the lower the battery
voltage the more it draws from the battery
, these are relatively common in the better brands of LED flashlights now, what it does is say you have a single
3 volt lithium battery like I have in my Surefire, the converter ups the voltage to 3.6 volts at 40mA, when the battery gets weaker it compensates and still maintains the same voltage for the LED, a regular bulb as the voltage decreases DRAWS more current
, and LED's works the opposite, the lesser the voltage the less current
what you have in the end is a flashlight that practically will never get dim, it will suck every last bit of voltage from a battery and keep that LED lit.
I'm saying this BECAUSE, yes you can wire simple LEDs with either individual resistors or wire them in series to a boats/RV battery system and its a moot point because you have that huge massive battery. A really good compact $150 flashlight like mine I can turn it on 20 times a day for a minute at a time for inspection
work and I replace the single
3volt lithium battery on average once every 4 months. Its a Surefire. LEDs is great, shockproof, explosion proof, cold for the most part though the new hi output ones do get really hot and the best part is that the LED draws so much less than a regular bulb, can be turn on/off a million times and if LEFT ON continuously will only dim 20% after 100,000 hours (11.3 years).