Why did my phone die even with battery saver on?

Battery saver isn't a miracle worker; it just reduces the rate of power consumption. It can still run out of juice eventually, so that might be what happened with your phone.

How long did your phone last after you enabled the battery saver? Did you use any apps during that time? That could definitely affect battery life.

Low power modes can help a bit, but they have their limits. What model do you have? If you're in an area with a weak signal, that could eat up your battery faster too.

Just a heads up: low power mode doesn’t mean zero power use. Your phone still drains battery, just at a slower rate. If you really need to conserve, turning it off completely is the best option.

I'm curious, what phone model are you using? Sometimes, older models have less efficient battery management.