How to Store Cordless Drill Batteries?

Don’t you hate it when you’re in the middle of a job and the battery runs out? If you don’t know how to store cordless drill batteries, then this problem is going to happen often. Proper storage can extend the life of your batteries and ensure they are ready when you need them.

In this article, we’re going to show you how to store your rechargeable batteries correctly every time, so they are fully charged when you need them. If you follow our advice, then you will extend the life of your battery.

The Basics of How to Store Cordless Drill Batteries

Cordless Drill Batteries

Most of us know there are different kinds of batteries. Lithium-Ion (Li-Ion) batteries are the newest major variety of batteries and are the gold standard for rechargeable batteries. Nickel-cadmium, or NiCd batteries, are an older technology that is still widely used. Nickel-Metal-Hydride, or NiMH, batteries are somewhere between NiCd and Li-Ion batteries in terms of performance and maintenance.

These different types have some things in common when we think about how to store cordless drill batteries. Here are some things you should do when you store your batteries:

  • Don’t drain your battery. Completely discharging your battery is usually bad for it and unnecessary. The only exception is when a nickel battery needs a full ‘exercise’ cycle to remove any memory effects.
  • Remove the battery. We know it sounds simple, but the battery should be taken out of the tool for storage. Leaving it inside the tool will cause increased self-discharge rates.
  • Store them somewhere dry. Water or moisture will wreck any battery. 
  • Avoid anything metal during storage. Anything that bridges the contacts could cause a short and, in worst-case scenarios, a fire. Don’t just throw them in the toolbox with everything else.
  • Avoid temperature extremes. Cold temperatures can help some batteries. Too much heat is bad for any battery. Cars, trucks, vans, garages, and greenhouses are all poorly insulated. These are poor choices for storage due to high heat.
  • Protect the battery. Use its protective plastic cap when you store it. Don’t drop it because visible cracks almost always indicate internal damage. The best storage containers are the manufacturer’s case or a container you can seal to keep out moisture.
  • Store them at the correct charge level. Here are some guides:
    • NiCd and NiMH batteries should be stored at around 40% charge. Doing so minimizes age-related capacity loss when storing the battery. You can store a nickel-based battery in a completely discharged state without any harm.
    • Li-Ion batteries can be stored at any level of charge. However, a 30-40% charge level produces the least amount of self-discharge.

What Else Should You Know?

As it turns out, knowing how to store cordless drill batteries is a hotly debated subject. Manufacturers make claims and tell users what to do. In the hard world of the jobsite, craftsmen have their own rules and ideas for what is best for their tools.

Let’s break down some of the more common things people still argue about.

Does Storage Affect the Battery’s Charge Level?

Yes, it does. All batteries self-discharge over time. The best batteries for low self-discharge rates are Li-Ion cells. They maintain their charge level for the longest while being stored. 

In addition to short-term charge loss, long periods of storage can result in loss of capacity in the battery. This is mostly avoided when the storage temperature is kept above freezing and lower than about 75° Fahrenheit.

Which Battery Stores the Best?

There is not an easy answer to this question. However, the short answer is Lithium-Ion. Common rechargeable batteries are either nickel-based or lithium-ion. Of these two technologies, lithium-ion has several advantages.

First, Li-Ion’s self-discharge rate is half that of nickel-based batteries. This means there will be a greater charge level remaining after you store your batteries.

Second, Li-Ion batteries do not have a memory effect. Nickel batteries remember their previous discharge and, over time, can stop delivering their maximum charge. This can be corrected through a full discharge and recharge cycle.

The best choice for most users, especially in the case of cordless drills, is a lithium-ion battery.

Can I Leave My Drill Battery on the Charger?

We already answered this question briefly, but there is more we can say. The cordless battery market is very competitive, and chargers are all different. Some batteries and chargers can be left connected.

When to Leave Batteries in the Charger

Many newer charges are made with features that allow batteries to be left in them. DeWalt, for example, designs its chargers with a maintenance mode. This allows the batteries to remain in the charger, fully charged, until ready for use.

The key things that allow batteries to remain in chargers are:

  • Trickle charging to offset the battery’s self-discharge
  • Charge level testing and power cut-off to ensure no overcharging

If your charger has these features, then you can probably leave your batteries connected when they are not in use. 

When NOT to Leave Batteries in the Charger

There is only one simple rule about not leaving your battery in the charger. Here it is:

Read the instructions from the manufacturer.

We know this sounds too simple, but it is really the best advice. Every manufacturer wants their tools and accessories to have a reputation for reliability. Their advice is going to be some of the best advice you can get for the specific battery, charger, and tool you are using.

Can You Leave a Drill Battery Plugged in All the Time?

Yes, but not if you want to have the best life of the battery. Of course, you can leave your batteries plugged in. We just think it’s a bad idea.

There are at least two reasons to avoid leaving your batteries connected:

  1. Batteries have a natural self-discharge rate. They lose power over time when they are not in use. Leaving them connected will increase this self-discharge rate.
  2. The potential for accidents and tool faults increases if you leave the batteries plugged in. Many people will think this is a small risk. However, why take the chance with the tools that you need?

Unplug your batteries and store them safely. Charge them if they need to be charged. If they don’t need charging, then put them in a case or sealed container.

If your battery is nickel-based, like NiCd or Ni-MH, then you should plan on recharging them before you use them. They can lose up to 40% of their charge in the first 48 hours of storage. Plan ahead and you won’t be caught out by a dead battery.

Conclusion

Cordless power options are expanding all the time. Just twenty years ago, cordless drills were still an emerging force in the market. Now, you can buy cordless drills, saws, chainsaws, and even more tool options. 

The question of how to store cordless drill batteries, and other batteries for other tools, has never been more important. Proper storage means power on demand for demanding jobs.

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