Slip indicator light and other electrical issues

Here we go again. A while back, we discovered that our inverter was draining the battery down, which resulted in the slip indicator light coming on, simultaneously with the loss of power to auto headlights, power to the cab lights, head unit, power door locks, cruise control, and remote locks. Fortunately, the light eventually went out and EVERYTHING started working again. The 1kw inverter was and is still disconnected.

Weeks later, after a very low battery condition again (obviously, something else is still draining it when not running), the whole shebang is back at it with the indicator lights and more. With the battery kept fully charged, if truck is not running, we have no cab lights, no head unit power (truck running or not), and even remote door locks cease to work. Again, this is all when key is off. Pain in the keister. I reset the ECU (disconnected negative terminal on battery for 10-15 minutes) twice over the last 3 days, and stupid light is still on with all the other mentioned issues. Alternator is strong and puts out a good 14+ volts, so at least I don't sweat charging. No fuses blown, nor trouble codes found either.

 

And 300+ miles later... all the issues magically resolved again.

 

Moisture getting in somewhere?

 

I think that it was the low battery that caused it. I guess I need to seriously consider the Genesis Gen3 dual battery kit to reduce the likelihood of it happening again.