How to reduce Android Auto phone battery drain by over 50%

[AussiePete]

Since I started using Android Auto (via USB connection) I've noticed there is a heavy battery drain and the phone gets quite warm. After a bit of searching this looks like a common problem. I've recently installed an AA Wireless adapter and found the drain is even worse. The first screenshot below shows over 20% battery drain for 2 and a half hours use. So I did some been experimenting and found the drain seems to be location services running continuosly alongside Google maps.

However I have found that exiting AA on the infotainment unit (on the AA menu select Exit) and leaving AA running on your phone, can reduce the drain by more than 50% (see 2nd screen shot) but still allows you to use AA functions including voice control and navigation when you need too.

 

[Alb]

I'm confused
My phone battery charges when it's plugged into USB.

 

[AussiePete]

I'm confused
My phone battery charges when it's plugged into USB.

Yes, but I've found Android Auto drain on battery can be as much as the phone gets whilst charging.

 

[Ozzie1989]

In theory the USB port should provide more than enough juice to charge and use the phone at the same time. Have you tried a different cable?

 

[AussiePete]

In theory the USB port should provide more than enough juice to charge and use the phone at the same time. Have you tried a different cable?

It’s not necessarily the charge I am worried about - it’s the 22% drain for 2 hours use. Even if charging this would result in charge cycling (ie app drain, phone charge, app drain, phone charge) high won’t do the battery any good

 

[Ozzie1989]

It’s not necessarily the charge I am worried about - it’s the 22% drain for 2 hours use. Even if charging this would result in charge cycling (ie app drain, phone charge, app drain, phone charge) high won’t do the battery any good

I'm not entirely sure it works as you describe. Open up any modern phone and the battery is connected to a regulator. If the phone is plugged in any power consumed by the phone will be taken from the 5v bus, the charging regulator will also draw power from this bus to replenish the battery. When power is removed power is drawn from the battery via the same bus.

I only suggest this as I've set up modern tablets to run direct from 5v with the internal batteries removed from the boards. If it were to 'drain the battery' this wouldn't work.

Using the phone whilst charging will only cause an increase in the charging time as there is less power (mA) available on the bus for the regulator to consume.

A bit like EV chargers, we call our phone plugs chargers but they are not, they are just 5v power supplies, the charger is in the phone and it decides how much current is to be consumed.

The calculation of battery usage by the phone is a basic calculation of CPU cycles X run time and as far as I'm aware doesn't take into account whether the phone was powered at the time of use or not.

I'm no expert however, just observations from my use of the tech over the years