Additional battery notes

docs/docs/walkthrough/phase-6/advanced-features.md

@@ -14,4 +14,6 @@ Wouldn't it be great if the system knew when you were running sensitive or resis
 
 ## Battery monitoring
 
-One of the downsides of OpenAPS is that it tends to drain your pump battery very quickly. Some users have had good experiences with Energizer Ultimate Lithium AAA batteries rather than alkaline batteries. Regardless of whether you use alkaline or lithium, you may want to consider a Nightscout alarm to alert you to when the battery is running low. You can do this by setting (in your Nightscout config vars) `PUMP_WARN_BATT_V` to 1.39 and adding `battery` to your `PUMP_FIELDS` so that voltage is displayed on your Nightscout site.
+Because running OpenAPS requires frequent communication with your pump, your pump battery tends to drain more quickly than you'd experience when not looping. Some users have had good experiences with Energizer Ultimate Lithium AAA batteries (getting ~1.5weeks) rather than alkaline batteries (getting ~2-3 days). Regardless of whether you use alkaline or lithium, you may want to consider a Nightscout alarm to alert you to when the battery is running low. You can do this by setting (in your Nightscout config vars) `PUMP_WARN_BATT_V` to 1.39 (if using lithium batteries, as is most common) and adding `battery` to your `PUMP_FIELDS` so that voltage is displayed on your Nightscout site. 
+
+The 1.39 voltage warning will give you many hours (reportedly ~8+) heads up that you will need to change your battery. If you don't change the battery in time and end up with a "low battery" warning on the pump, the pump will still function, but RF communications will be turned off and you will not be able to loop until you put a new battery in.