Phone Battery Use Conundrum

[Prudie]

I have a problem that no-one so far has been able to explain so thought I'd give it a go on here...my phone has irritated me for a while as when I'm home and it's connected to home WiFi the battery used will drop from 100% when unplugged say at bedtime to about 18% overnight. If I forget to close some tabs eg WhatsApp it will go flat overnight.
When I take it out of the house say to work the battery reduction is minimal. I never use roaming /mobile data and have turned Bluetooth off. Something wrong with phone you may say BUT I have come away (abroad) and am staying in a house with WiFi that my phone is connected to and the charge is lasting for up to 2 days, No major drainage at all. What can cause this discrepancy in battery use when the settings on the phone have not been changed in the 2 locations????

[Sunk]

Not answering your question, but why do you have apps open when you are asleep. I close all apps at night. Nighttime is also when I plug in and charge my phone so that it is 100% in the morning.

[Prudie]

Because I forget to close them sunk. And yes I usually charge overnight but sometimes I have to take the phone to bed for an early alarm and it will drain massively,

[Hopkirk]

Can't you charge it in your bedroom?

[Prudie]

Yes but thats not the point why does it go flat in about 8 hours doing nothing when connected to Talk talk in my home and yet lasts well over over 2 days with someone else's WiFi. Or is it maybe the phone signal part?

[sunny-dave]

1. Is it running auto updates for apps over wifi when at home? That canes the battery of older phones if not plugged in.

2. As an experiment, put it in airplane mode & then only turn the wifi back on - if it still goes flat overnight then that excludes any possible mobile data or bluetooth drainage.

[Prudie]

Thanks for a sensible suggestion dave, not ignoring it but can't try it out until I'm home.