Depending on the phone/battery capacity, I can get through 2-4 batteries a day, so they're not just sitting idle, hence the reason for buying them in the first place.
It's 2GB on this phone.
batteries deteriorate so not a good idea to buy a battery and do nothing with it. Secondly only 1gb ram which is too low these days, pay a bit more and get 2gb so you can actually use it.
That's why it pays to check for spare battery availability in advance. I usually purchase 2-3 spares at the same time (batteries for the Doogee X6 Pro were only about £8 each) as I order the phone.