Is It Bad To Leave Batteries In Your Cordless Tools (When Not In Use)?

Many DIYers love cordless tools because they are portable and convenient.

But did you know that the way you use and store your cordless tools might damage their batteries?

If you are a savvy DIYer with several cordless tools, you might be wondering:

Is It Bad To Leave Batteries In Your Cordless Tools (When Not In Use)?

YES, it is bad to leave batteries in cordless tools. Leaving batteries in tools causes a higher self-discharge rate that eventually harms them, potentially sending them to an early grave. For this reason, always take the batteries out after every use and store them safely.

Whatever cordless tools you have, their batteries require a bit more care to get the best life out of them.

This post will cover more on how to take care of your cordless tools’ batteries to keep them running strong and last longer.

The Five Best Practices To Preserve Battery Life

Battery-powered tools are becoming much more powerful than ever, thanks to the advancements in lithium-ion technology.

While this has significantly increased their popularity, what many people do not understand is that even rechargeable batteries die when not well taken care of.

If you are a hobbyist with many cordless tools or are planning to buy one, here are tips and the best practices to preserve your tool’s battery power.

1. Remove The Battery

Leaving batteries in tools causes them to self-discharge faster.

To preserve battery life, switch off your tool and remove the batteries whenever you are not using it and not anticipating using it for an extended period.

Also, remember to store it in a safe spot, preferably in a battery case.

2. Use Batteries Regularly

The lifespan of batteries, including rechargeable ones, decreases with the lack of use. As such, using your tool regularly can help preserve battery power.

Considering the harm lack of use can cause, if you are sure you won’t be using your cordless power tools often, you may want to consider corded options.

This way, you can save yourself the cost of replacing dead batteries every while.

3. Store Batteries Properly

There is more to storing tool batteries than many DIYers know, and you could be killing your batteries without knowing. So, what is the best way to store batteries?

Like other types of batteries, cordless tool batteries should be stored in their original carrying case and a cool, dry spot.

While it can be tempting to use metal for superior protection, make sure to use the plastic cap that comes with your battery.

This is important because metal can cause short-circuiting or damage to the terminals.

Talking of temperatures, colder temperatures may help preserve battery life. However, you should never store batteries in extremely cold spots.

Unlike older batteries, modern batteries do not degrade when placed on concrete, so you can take advantage of your concrete floor to keep batteries cool as long as it doesn’t get wet.

On the other hand, heat, medium or extreme, will gradually kill your battery, with extreme temperatures causing rapid damage. This also holds when you expose batteries to direct sunlight.

4. Store At The Proper Charge Level

It is always advisable to charge cordless tool batteries regularly and leave them plugged in until they are fully charged.

This is very crucial when you want to use your power tools.

However, when it comes to storing batteries for an extended period, it is recommended to keep the battery charge at roughly 50% for optimal lifespan.

For Li-Ion batteries, it is even better to keep batteries at 30-40% of their charge. A lower battery charge helps keep the self-discharge rate at the lowest possible.

If your cordless tools use NiCd or NiMH batteries, 40% – 50% charge can help minimize age-related battery power loss.

All in all, you can safely store nickel-based batteries when they are completely discharged.

5. Handle Batteries With Care

Handling your power tool batteries with care is as important as storing them properly. In fact, many batteries get damaged due to improper handling.

Whether it is forcing the battery into the tool or charger or cracking it, you might be damaging your batteries. Just be gentle with cordless tool batteries, and you may increase their lifespan.

Five Things That Might Be Killing Your Cordless Tool Batteries

You might be inadvertently killing your cordless power tool batteries. Here are some of the things that might be damaging those batteries:

1. Leaving Batteries In The Charger

While it is a good idea to let your power tool battery charge until it is fully charged, leaving it in the charger could cut down its lifespan.

When batteries are left in the chargers for an extended period, especially after they have completely charged, they can overcharge. Ultimately, this will kill your battery.

You can avoid this by removing batteries from the charge once they are charged. Thankfully, most have an indicator to show the battery is fully charged.

2. Deep Draining Batteries

It can be very tempting to continue running your power tool, even after the battery indicator warns you.

This especially happens when one is nearing completing a project. But do you know this can drastically damage your battery?

Running batteries all the way down forces them to work harder and eventually overheat.

This shortens battery life, and over time, it can permanently damage the poles, sending your battery into an early grave.

This can be avoided by recharging batteries when your tool starts to slow.

Of significance, if you are done with your project and are recharging the battery before storing it, be sure to charge it to about 50% of its capacity.

This will keep the self-discharge rate at its lowest for the time you won’t be using the battery.

3. Storing Batteries When They Are Fully Charged

Fully charged batteries that remain unused for a long time tend to self-discharge relatively faster.

They also pose a more serious threat when exposed to high temperatures.

For safety reasons and to preserve battery power, store cordless power tool batteries at about 50% charge.

4. Moisture

Moisture can cause exposed metal components on power tool batteries to rust.

Although keeping batteries in a cool spot can help preserve their power and ensure they last long enough, it is extremely important to ensure they never get wet.

To keep cordless tool batteries free from moisture, consider putting them in the battery case they come with when brand new and store them in a place that doesn’t get wet.

5. Using The Wrong Charger

Although universal chargers do a great job in helping DIYers charge different batteries whenever they cannot access their chargers, not every charger is fit for power tool batteries.

Whether you misplaced your battery’s charger or lost it, using a different charger other than the one that came with the battery can potentially damage it.

Usually, cordless power tools come with a charger that detects and indicates when the battery is fully charged, hot, or overcharged.

If you have lost your charger or it defaults, it is best to contact the tool manufacturer, and, depending on the batteries you use, they are likely to recommend a better option.


Cordless power tool batteries need a lot more care than you can imagine.

If you have been contemplating leaving batteries in tools or not, hopefully, this post will help you store your batteries properly.