Last night I thought I needed to buy a new battery, for my 3 year old, low-end, Samsung Galaxy phone. This morning, I looked in Settings > Battery and saw that the Google Play services category was using the same percentage of battery, when the phone was idling, as the Screen was. Approximately 25% for each category, at that time.
I had not changed any settings for the Google accounts on my phone, or, for Google Play services. There was a sudden, very large, increase in battery consumption by Google Play services.
I deselected a number of items in Settings > Accounts > Google > (choose each Google account if there is more than one) in the “Sync settings”
At this time, my phone is showing 32% for Screen consumption and 13% for Google Play services, under the “Battery” category in the “Settings” for the phone.
Because I had not changed any settings in my phone before the sudden increased drain of the battery, I suspect that Google and/or Samsung changed something during the past few days.