Posted page 122 of this manual -
https://my.teslamotors.com/sites/de...touchscreen_7.0_das_ap_na_r20151028_en_us.pdf - but im sure i've seen it in the onboard manual as well:
About the Battery
Model S has one of the most sophisticatedbattery systems in the world.
The mostimportant way to preserve the Battery is toLEAVE YOUR Model S PLUGGED IN when youare not using it. This is particularly important ifyou are not planning to drive Model S forseveral weeks. When plugged in, Model Swakes up when needed to automaticallymaintain a charge level that maximizes thelifetime of the Battery.There is no advantage to waiting until theBattery’s level is low before charging. In fact,the Battery performs best when chargedregularly.Note: If the Model S Battery becomescompletely discharged in a situation in whichtowing is required, the owner is responsiblefor towing expenses. Discharge-related towingexpenses are not covered under the RoadsideAssistance policy