I turned and left a cargo light on overnight with no ill effect on the battery. Now they are LED. I switched the interior bulbs a few years back. Yes they're bright and easier to spot when left on since i have the black interior, with the exception of the cargo area Now I'm sure corrado doesn't want to volunteer and find out if LED would've made a difference, LOL! It's probably safe to say the cold and short trips stressed the battery, and the tailgate left open overnight being just enough to kill it. At least all is well for now.

 

I'm always concern about switching to LED bulbs and always question
if there's a "heat" facture on the lens and sockets.

 

First, LEDs are diodes, not bulbs. Secondly, since they draw far less power than bulbs, they tend not to get as hot. My understanding is, and I did not get this in high school physics since they did not exist then, that they use almost all their energy to generate the light, not the heat, which is one reason for the energy efficiency. The sockets are metal designed for the heat from a conventional 12 volt incandescent lamp, which quickly gets too hot to touch. I've had these in my two cars for several years with no problems, only advantages. I might add that when looking into them, the issue of heat fractures resulting from this change never appeared. The real issues are getting LED fixtures which will fit into the space available. Thus you should not be "concern" (concerned?) about making the switch. Look at the posts here, and look at the providers who specialize in marketing the LED lamps for automobile use and I think you will find that there is virtually no problem with heat related consequences.

 

Not to add more complexity to the mystery of the drain, but I know as a fact the interior lights turn off after several minutes as I've seen that many times when washing the car indoors at night. Doors are left opened during the duration of the vacuuming, window cleaning, etc and never had an issue starting the car afterwards.

With that said, it cannot be the interior (or exterior lights) draining the battery. What other energy drawing system got (or gets) triggered when doors are opened that caused the battery to drain.

 

I heard this more in the past prior to the mass availability of LEDs. You had individuals replacing their standard bulbs with halogens or other brighter bulbs from lesser sources which would draw more power. These replacements would be brighter, however, they also drew more power and put out much more heat. They also burned out quicker. The result would be melted wiring harnesses, lenses, and sockets.

For example, a standard H11 halogen bulb might draw 55W while some of the brighter replacements drew upwards of 65W or more. With newer technologies today we see more and more bulbs being able to output a brighter and whiter light without having to resort to increased power consumption. The move to LEDs will only increase due to their low power consumption and low heat output. Their efficiency has a lot to do with the color output and manufacturing process for the diode.

The main problem, as I see it, with LEDs is that you need to be mindful of their output -- measured in lumens. When LEDs first started to become popular the diodes were weak and expensive. The result were products with not much output as they were mainly packaged as a single diode. Today, the diodes are not only brighter but are also cheaper allowing the manufacturers to create products with multiples of the LED diodes. As a result get cheaper and brighter products, though we still need to be mindful of the specs.