Tag Archives: Battery Tips

How do I know when my rechargeable battery is at the end of its life?

You just charged your device, but it’s already running low. You used to get 6 hours out of a charge and now you’re only getting 90 minutes. These situations are common in our daily lives. However, before you discard those batteries, let’s learn how to check their condition.

There are two common indicators that your rechargeable batteries need replacing:

  1. The battery has been used extensively over a few years, and it’s lasting a fraction of the time that it used to.
  2. It’s taking significantly longer times to fully charge.

Rechargeable batteries are most commonly worn out by three things: number of charging cycles, heat, and age.

You should expect 500-1000 recharge cycles out of any given battery before you’ll see noticeable degradation. Once you’re hit this many cycles, you can reasonably assume that the battery is at the end of its life. And, rechargeable batteries work best when kept around 68-77 degrees Fahrenheit (20-25 degrees Celsius). Keep them out of direct sunlight when charging.

However, there are some indicators that might suggest the battery and the device might not have great contact.

  • The charge never completes or takes a much larger amount of time (2 to 3 times longer than the normal charging time).
  • When the battery drains quickly, but it’s only been used (recharged) a few times.

In these cases, the best course of action is to clean the battery terminals and the charger connectors. A microfiber cleaning cloth will work, and isoproyl rubbing alcohol is typically safe for cleaning electronics without leaving behind moisture and other residue.

It is worth noting, though, your phone’s battery is also affected by how you use your phone. Things like the apps you install, the stuff you collect, the number of ads you’re exposed to on websites, the number of notifications you received, whether you are using WiFi or data all effect how much strain is put on the phone’s battery. The more you ask your phone to do, naturally will cause it to deplete faster.

Can I mix old and new batteries?

Short answer: Don’t.

It can be tempting to only swap out only the battery that’s died, but you shouldn’t. It’s like trying to write an essay with your non-dominant hand: You might technically be able to do it, but you’re not going to like the end result.

So, replace all of the batteries at the same time. Using only fresh batteries together will maintain their lifespan and is much safer.

Remote with Batteries
See this remote with two different batteries? Don’t do this!

For example, your TV remote uses two AA batteries and is dying. You only have one fresh battery on hand. If you only replace one of the batteries, the good battery will not last. The new battery will have to work extra hard to meet the power demands of the remote, which will shorten it’s lifespan significantly.

Also, that dead battery still in the remote? It runs the risk of overheating as the fresh battery works. The reason for this is the fresh battery is delivering large current into a dead battery that has high resistance. This causes excessive heat to build up. This is explained by Joule’s law, the relationship between electrical power and thermal (heat) energy.

Two fresh batteries avoid this as they increase in resistance together as they deplete, limiting the current the batteries are supplying. Most batteries are designed to be safe under these conditions.

So, just replace both of them and save yourself some grief!

We recommend using batteries from the same brand, too, since there can be small differences in the voltage and capacity of the battery. AA alkaline batteries are rated at 1.5 volt, but this number is an estimate. Some manufacturers could round up from a number like 14.9 volt, and then another could round down from 15.2 volt. It’s a small difference, but this electrical imbalance could negatively affect performance.