If your battery fails, you’ve got an expensive problem to solve. Replacement laptop batteries typically cost $100 and up — and it’s important that you buy them from your manufacturer, or, if buying from Amazon or Newegg, be sure the battery is OEM, for original equipment manufacturer. In other words, the battery’s brand needs to match your laptop’s brand.

Third-party laptop batteries, while likely cheaper, tend to have inferior battery life and even tend to be downright unsafe. Do not buy laptop batteries from other companies — I can’t emphasize this enough.

If you buy a bad battery, this could be your lap.

To determine what battery you should buy, you should first identify your laptop’s manufacturer and then the model for your particular machine. A manufacturer name and series name can generally be found in the branding on your laptop, and the model number will usually be printed on the bottom of the laptop.

If you still have the case for your laptop, you could use the boxing and instruction manuals to find out your laptop’s model number — otherwise, you’re going to need to conduct a search for your manufacturer and product line until you find a photo of the laptop that looks the most like yours. Search thoroughly — buying the wrong battery could result in a battery acid lap-dance that I’m sure you don’t want to experience.

After determining your series and model, head to your manufacturer’s website and start looking for where you can buy new batteries. If you can’t, do a search to find where you can buy replacement batteries for your machine or head to a local tech shop to see how they can help you.

Sometimes, a manufacturer will sell batteries with different numbers of cells in them. The more cells, the longer the battery lasts, but the heavier the laptop will be with the battery inside it. It’s a trade-off.

Once you’ve found your new battery, congratulations!

To make this one last longer, be sure to not keep it plugged in all the time. A good idea is to wait until your battery gets low to charge it, give it a full charge, then unplug it again — while it sounds silly, it tends to make batteries last longer, because eventually they run out of recharge cycles, and keeping your laptop plugged in 24/7 can result in those cycles being devoured so badly that you can’t go an hour without finding an outlet. Also, consider using AC power whenever you can.

Finally, our free app, Battery Optimizer, can also help your battery go much further between charges. Give it a try!