I was facing the same issue, but I guess with the recent security patch update of aug via developer open source it's working fine.
You guess it's working fine? Not sure to understand what you mean.
Thanks guys for your answers, it looks like this will take ages to be fixed (if ever). It seems that samsung does not even take this in consideration, they even stopped answering to my feedbacks in the members app. They know that there is the issue thouggh
I've lost faith in Samsung fixing this issue. I've now purchased an Honor 9 lite to use until my contract is up for renewal. Its so refreshing getting to the end of the day with 40% of my battery remaining. My 1 year old S7 had to be recharged twice a day after updating to oreo. Poor show considering the honor and S7 (flat) have the same battery capacity. I loved my S7 but after this experience I will never buy another Samsung device again.
The same battery drain on my s7 flat after august patch. In background is too high and when i using an app, speed is like: look at batt %-is 75, look again in a minute-is 74, like a water. My opinion is the same to many of you guys, samsung is never in my pocket again. Leader in Asia market bacame huawei, is this randomness? Samsung is killing himself, slowly but reliably)))
Lol @ Alex130- you're exactly right- the battery drains right out like a dripping water faucet. I posted on here in July right after Oreo ruined my S7, found no solution, went to Sprint (U.S.) and thr factory reset my phone, I lost a ton of stuff that was supposedly backed up, and here I am a month or so later with exact same issues when we're all told "factory reset" is the solution. Never again Samsung. Will look to Google for my next smartphone after I can't stand this one anymore with CONSTANTLY having it plugged into either a charging bank or electric outlet.
Kind of important update. As part of my summer "science school project" , whole past week I was on different mobile network operator, name it "B", using prepaid SIM card. Same phone, same firmware, just new MNO. And the whole week I had great battery life. Not only sleep was 2% for 8h at LTE, but for example 1h of Spotify with all-new non-cached music consumed just 3-4% of battery at LTE. This is very sane and just great numbers.
OK, back to my usual MNO "A". I asked support, why on they network I had battery drain and they suggested to change my SIM card for free. There is little chance that faulty or bugged SIM card can bring LTE drain problem but I agreed to give a shot. I've got new SIM card, installed it yesterday, upgraded firmware to the latest ERH6 and after 20h drain began.
So, there is some incompatibility between my S7 and mobile network, leading to this 4G drain bug. It can be on my side (hardware or firmware part of modem or kernel or just Oreo firmware bug), on my MNO side (base stations firmware bug, bad tweaks, optimizations, network infrastructure flaws) and on both sides.
Now I plan to permanently migrate to MNO "B". It's not bulletproof solution, I can face LTE drain in some other city or may be my "happy week" was just one week and things will get wrong soon. Will see.
And my current advice to you - try other mobile network operator, just get prepaid SIM card. Or wait for a patch.
PS. One my friend here has same Galaxy S7 and don't have LTE drain using MNO "C". So this is network depending bug.
PS2. I suggest a new name for our topic: "Cell Standby / LTE / 4G battery drain on Galaxy S7 on Oreo". This is more precise than current "everything-drain".
I find it super funny how Samsung is asking $1,000+ for the Note9 and how the S7-8-9 were $600-800 dollar phones, yet it seems that it's going to take them 20 updates and 6 months later to fix a battery drain problem that's so bad people need to carry their chargers with them at all times. If that's what's going to happen to the Note9 and S8-9 when they get Android P, then I just feel super bad for the people that spent this kind of money for the phone.
It's very weird how some of us have the problem and some don't, but nonetheless, that's where manufacturers should stand behind their products and customers.
I'm still using the stock-based custom ROM called DevBase from XDA with the ERG2 base, ERG2 modem, and July patch and getting amazing battery life both on LTE and Wi-Fi in idle and during use.
Android system taking a lot of battery.
• Use the unmonitored and always sleeping apps function from Settings > Device maintenance > Battery > Unmonitored apps you should have no apps in there (delete if anything's there). Use the Always sleeping apps function and put all apps in there that you won't need push notifications for.
• Check to see if you have any apps listed in the crash report. If you go to Settings > Device maintenance > click the paper icon at the top right and it may list apps that have caused crashes which may result in a bit of battery drain.
• Go to Settings > Device maintenance > Let it load and click Optimize Now.
• Turn phone fully off. Press Volume Up, Home and power button at the same time until the Samsung logo pops up. It'll take a minute to load and may look intimidating at first, but wait until it loads a black screen. Use the volume up/down to scroll and power button to select and then wipe cache partition and reboot phone.