Surface book 2 battery 2 only being used

Question

Is it normal that Battery 2 is only being used after it gets down to 80% because from 80-100% both batteries are being used, but when it gets below to 80% only Battery 2 is doing the work, also when Battery 2 gets to 35%, now Battery 1 starts to being used and Battery 2 doesn't get used. Once both have 35% then both start to work simultaneously. I have the most Updated Windows and firmware.

Answer 1

It is normal for the larger base battery (Battery 2) to shoulder most of the burden, most of the time, so that when you do want to detach the tablet (containing Battery 1) it will last longer: see longer explanation here 

https://www.neowin.net/news/surface-book-understanding-the-benefits-and-drawbacks-of-the-devices-batteries/

Not sure why yours then goes in for a bit of back and forth - but that's the general principle.

Answer 2

Hi, MauriUresti Herrera!

Thanks for reaching out to Microsoft Community and posting your inquiry regarding your Surface Book 2 batteries. We appreciate you for taking the time to let us know about this. I recall using a Surface Book before and there are times that one or the other will work alone, then both will run. I believe it depends on what is running in the background. What I can do here is to research further on this for you though. In the meantime, you may visit this page to help you out Maximize your Surface battery life to make most out of your device.

Another helpful information from this link on How to charge Surface, it states there that:

The batteries in Surface Book may also charge at different rates, depending on the power state of each battery. Whichever battery has less than 20% charge will be charged first. After both batteries have been charged to 20%, both are charged at the same time.

We hope this helps you out.

Kind regards,

Janette_Z