Three Laptop Battery Charging Myths

Many of our customers ask us for tips on proper battery care. We’ve heard a lot of different things said about batteries, some true, some not so much. Don’t believe everything you hear! Here are some myths about charging laptop batteries.

MYTH #1: You should fully discharge your battery before charging it again.

This rule used to be true with the old nickel-based batteries that used to be the battery type of choice for laptops, but have since been mostly replaced by lithium-based alternatives. The so-called “memory effect,” which was the reason  a regular full discharge was recommended, does not exist in modern batteries. Fully discharging your battery is not only useless- it can even be harmful to your battery.


MYTH #2: Using a higher amperage/wattage charger will harm your battery.

There is nothing wrong with using a charger or power adapter with a higher amperage or wattage than your old charger. What is true, though, is that using a lower amperage/wattage charger can be bad for your equipment. The indicated output amperage on your charger doesn’t mean the amount of amps it will give; rather, it refers to up to how much it can give.

When using a new charger with a higher amperage/wattage charger than your old charger, one of the following things may happen:

  • Your laptop charges faster than it used to
  • Your charger runs cooler than your old charger
  • It works exactly the same as your old charger (worst case scenario)

When using a new charger with a lower amperage/wattage charger than your old charger, one of the following things may happen:

  • You manage to use your laptop while charging, your system throttles (severely limits hardware usage to cut down power consumption. (best case scenario)
  • You can charge your laptop very slowly while it is turned off, but not while using the laptop at the same time
  • Nothing happens
  • You damage or burn out your charger

Make sure that the voltage on your new charger is not more than 10% higher or lower than your old charger. While an exact match is preferred, it is perfectly safe to use a charger within safe variable voltage. Example; the HP CQ40 Series line of laptops usually comes with a 18.5V 3.5A (65W) charger; but it is also compatible with a 19V, 4.74A (90W) charger. You will also need a charger that has a charging pin that is exactly the same as your old charger (no room for variation there; it either fits or it doesn’t).

MYTH #3: Using your laptop while charging it will diminish your battery’s capacity.

One of the most commonly-repeated myths is that keeping your laptop permanently plugged in will damage it. Unlike the two myths above though, this myth does have a grain of truth in it. Keeping your laptop plugged in isn’t actually a problem; once your battery is full, the power management features in your laptop will stop charging it, and draw any power the laptop needs from the charger alone.

What will damage your battery though, is heat. Laptops can get pretty hot, especially during high-workload usage. Continuous exposure to that heat can diminish your battery’s ability to hold a charge. If you plan on leaving your laptop plugged in for weeks on end, remove the battery. Ideally, you want to have the battery at around a 80% charge when you take it out; it’s a level that’s ideal for storage.

All batteries have a finite number of cycles that they’re useful for; all batteries stop holding a charge eventually. However, with smart use and proper care, a good battery can still last a long time.