Overcharging, undercharging, extreme temperatures, these are all variables that can shorten the life of your lithium-ion battery (used in iPhones and Androids). In order to extend the life of your battery, you’ll want to use the 40-80 rule whenever you can.

I know what you’re thinking, “Isn’t it suggested to wait to charge phone batteries until they are completely drained?” Well, actually, no. That was the suggested recommendation for getting the most out of your battery in the past, but new research has shown that this method is actually not best for batteries. In fact, the rule really only applied to nickel-based batteries, which have taken quite the backseat in today’s electronics. They’re rarely used anymore.

The best practice for ensuring that your beloved electronics have a long life, is to treat your lithium-ion batteries delicately.

The rule goes as follows: First, stop charging your batteries from 0 to 100 percent in one sitting. This isn’t as efficient as you may think. Instead, keep your battery life somewhere between 40 percent and 80 percent. This ensures you’ll have enough juice when you need it, but keeps from overheating which can result in a shorter lifespan.

Research shows that extremes wear out the lithium-ion batteries, rather than extend their life. Each and every time you plug in your electronic, whether it be a smartphone or a laptop, it will actually hold a little less energy than it did the time before. (Makes me rethink every time I plug my phone in between uses.) You’re actually doing your gadgets a favor by letting the battery drain a little, rather than plugging it in once it hits 70 or 80 percent battery life (as I tend to do quite often). Completely explains why after a couple of months (or years, if you’re lucky), your laptop battery needs to be replaced. The battery becomes weaker after a certain number of recharge “cycles,” which for lithium batteries is typically somewhere between 300-500 times, according to Battery University. If you use the “full spectrum” of a lithium-ion battery, you cause the battery stress which reduces its lifespan.

So let me break it down for you, every time you refill the battery from 0 percent to 100 percent, that’s one cycle. By recharging your device from 0 percent to only 50 percent instead, you’re actually tripling or quadrupling the number of recharges the battery can undergo before it’s “kicked,” opposed to overexerting the battery and, in turn, shortening it’s lifespan. That’s a whopping 1,200 to 1,500 cycles, as opposed to the mere 300-500 cycles you’d get if you fully charged the battery each time.

Another variable that can push your battery beyond its limit are extreme temperatures. A big no-no is leaving your electronic device on and plugged in for long periods of time, which can cause overheating. This can permanently decrease your battery’s capacity by 35 percent in just one year. So at all costs, do your best to avoid leaving your gadgets in high-temperature areas. And, although this one seems pretty obvious, sub-freezing conditions can kill a battery. In fact, it can kill it the instant the device it’s powering is turned on, as opposed to the heat that just simply lowers the battery’s capacity.

Now we all know that keeping your device charged at the optimal 40 to 80 percent at all times is simply unrealistic, however it is good to know and be aware of the fact that your batteries prefer to sit somewhere in the middle. So when you can control your device’s “charge percentage,” opt for a number between 40 and 80.