Phone

[ste49]

How long should a full charge last for

[Glenntech]

All depends on how you use it and what you have installed.
What's using background processing.
How much screen time you use.

Generally with modern phones now with normal sort of use.
You'd be looking around a day or two.
A older phone depends on battery age and condition.
Reckon about a day ish.
But the battery life is subjective

[JAMES4578]

@ste49  I would agree with @Glenntech 's post.  We all use our phones slightly differently  and cannot be definitive but on average Battery on your Device should last around a day.  If you are a heavy user of power intensive apps that is obviously going to have an impact.   I guess you are asking this question because you have not been that impressed with your Battery life lately.

For general optimisation only have connections such as Bluetooth,GPS and Wifi running when they are needed and put apps which are not used regularly into sleep Mode.

Software support though for the S9 ended over a year ago  https://www.xda-developers.com/samsung-ends-software-support-galaxy-s9-galaxy-s9-plus/    Therefore you may to consider a new Device at some pont.

[Adrian_Kilgour]

Depends on how you use your device. If you watch video content it will be shorter, if you use it for just calls and texts then it will last longer.

[ste49]

Thanks