high battery drain again

[jhu321]

one possibility is that the engine needs to reach a certain RPM to charge. I don't know about cars as i haven't really worked on a car charging system, but I've worked on my bike's(ducati). the Ducati would only charge if you're above 4000 rpms and below 7000rpm's the reason being the alternator wouldn't put out enough voltage for the voltage regular to convert into a consistent 14V current to charge the battery. so if you leave a ducati at idle for a long time, it can actually drain the battery and kill itself. but that could just be beacuse motorcycles have limited charging systems due to minimizing weight