Apple

I just downloaded a 253mb banking app on mine and it dropped from 26% to 25%.

I just got a new battery installed at the Apple Store in my spare OGSE 2016 and it still drains pretty quick when I use it and I don’t even have a SIM card in it. I’m inclined to agree with other commenters that modern day apps are likely a lot more demanding than they were back when the phone came out.

Back then when the batteries were designed for the SE (or even the 5S ten years ago, since OGSE has its hardware), apps and even iOS was not as much energy consuming as today. Like imagine it in reverse, today’s iPhones would survive like 2-3 days easily with basic usage, if we could use them in 2013. You know what I mean. I guess its totally normal, especially with refurbished phones.

These people saying normal do not have apple certified new batteries. Take it in for a new one at the apple store and be done with it. It is expected with a used phone or phone that has not had a charge sitting in a drawer for years at 0%.

That looks very normal. The 2016 iPhone SE does not have good battery life, even if your battery is in good condition, that's just how it is unfortunately. It is using a 14nm CPU which is outdated and not very power efficient, plus the battery capacity is 1624 mAh. I notice the battery life is worse when there's heavy WiFi activity (such as downloading apps via WiFi). Streaming audio and video isn't too bad in comparison (especially if you stream at lower quality).

It's also possible that the iPhone software has not been fully optimized, you may need to wait a few weeks before the iOS system will optimize itself (it'll know what apps/services you use the most and prioritize those apps while putting the rest to sleep). This process can take a few days or weeks.

Also the battery software might not be calibrate. It needs to go through at least 3 full charging cycles (100% to 0% 3 times). There are iPhone battery recalibration instructions which you can look up, but the quick instructions:

• charge to 100%
• once at 100% then keep plugged in for another 2 hours
• discharge battery to 0%
• keep trying to turn the iPhone on to drain the battery more
• once dead then leave it dead at 0% overnight for 8 hours
• next day repeat these steps 2 more times

Apple's battery software is sometimes not very good (the battery percentage goes up or down when you restart or turn on/off the iPhone). So you may need to recalibrate the battery. This issue is more likely to happen after a battery was recently replaced, the software was updated, or if the iPhone hasn't been used in a long time.

The problem with buying used phones, it's the same as buying a used car... You'll never know what was done to the phone or what may have been repaired. It might be possible that the battery was replaced with a generic aftermarket battery which shows the battery health at 100% but the actual battery life isn't really good. You can ask the seller for details on the phone and if they used an aftermarket battery or genuine battery. Since it's a 2016 iPhone model, it's very likely the battery was replaced as it's an old phone and there's no way it could still have 100% battery health unless the battery was replaced.

4-5% is excessive. Battery health might be misleading? Especially if the device has been sitting idle for a long time. That’s the only thing I can think of.