Most of us — casual users and enthusiasts alike — are forever searching for smartphones with the longest battery life. And while fast charging keeps us topped up every day, the absence of replaceable batteries means eventually, the lithium-ion cells enclosed in our phones are going to age and deteriorate, making it harder to maximize battery life.

If you’ve held onto a phone for a couple of years, you’ve probably noticed the battery doesn’t seem to last as long as it did when your handset was brand new. Four or five years down the line, many phones struggle to make it through the day on a single charge. Holding onto a phone even longer can even spell trouble for reliability too as you may face sudden shutdowns.

Unfortunately, battery capacity inevitably declines with age. But that doesn’t mean you can’t do anything to prolong the lifespan of your smartphone’s battery. If you’ve ever wondered what the best way to charge your battery is, here are some scientifically proven tips to maximize battery life and health over the lifetime of your device.

Partial charging is just fine for lithium-ion batteries and even has some positive benefits.

Notably, operating at a low voltage is good for a battery’s lifespan, increasing the number of available charging cycles before you start to see a significant reduction in capacity. Roughly speaking, every 0.1V decrease in cell voltage doubles the cycle life, according to Battery University. Therefore, charging up your phone in that 30% to 80% range keeps the voltage lower and might slightly prolong the battery’s lifespan.

Lower battery voltages help prolong capacity over time. Green: lower voltage charging for first ~65%. Yellow: Start of constant voltage. Red: Long period of high voltage charging for last 15%.

Smaller but regular top-ups are much better for Li-ion batteries than long full charge cycles.

Using up just 20% of your battery between charges isn’t practical, but topping up when you’ve used about half will improve your battery life over the long term, especially if you avoid charging up to full each time, too. The bottom line is that smaller, regular top-ups are better for Li-ion batteries than long full charge cycles. Newer phones allow you to impose a battery charge cap around 80% or 90%, reducing stress on the cell and helping it last longer.