Parasitic battery drain?

1. It is sending out a very brief packet from the car's cell phone transmitter on a schedule.
This should not be too much power usage, and the receiver of the cell phone is always on at your beck and call, and gadknows whatelse.
As we know, our cell phones can sit there with the receiver on for a very long time on the very small battery.

2. Well actually, it's done over the cellular network. I guess cars can be linked to your home wifi for some reason.
And your cell at home may be using the wifi to contact toyota's digital mothership, which then calls the car's cellular phone system. So there's always cloud service involved.

3. You Da'Man !!

 

The Toyota app and/or the Toyota Connect services (with or without a partial/full subscription) do not cause a significant parasitic drain.

 

What I have discovered is that you do not need to connect a battery maintainer regularly. It does not alter the setpoint of the battery-management system (BMS), which is about 80% SOC. In a few days after fully charging the battery, the BMS will deliberately drain the battery to 80% SOC, even while driving the car, and will keep it there.

The Prius battery could only fail and you need to connect a battery maintainer only for the following two reasons: (1) The battery already comes with a low SOC from the dealer. (2) You do not drive the car for at least 40 minutes in a single day for at least once a week. Otherwise, there is no issue with the battery, and you do not need to connect a battery maintainer. And, of course, if you drain the battery for any reason, you need to charge it with a battery maintainer—the BMS will not bring it back to health for you.