Your power tool batteries will lose power gradually. That is bound to happen. Eventually you will have to throw out the lifeless battery from your cordless woodworking tool and get a new one. But there is a LOT you can do to increase the life of the battery. You can even make it last for the life of the tool itself if you are willing to take on restoring and refurbishing the battery. But that’s another topic.
A cordless tool rechargeable battery will lose its capacity to hold a charge over time. This happens with age, and with the rigours of usage.
In this post we talk about some great tips for battery care and maintenance that will extend the life of the woodworking cordless power tool battery to its absolute maximum. What you have to do depends on the kind of battery your power tool has, which in technical terms is known as the ‘chemistry’ of the battery.
The 3 kinds of batteries found in 99% of woodworking tools are Li-ion (Lithium Ion), Ni-Mh (Nickel Metal Hydride), and NiCd (Nickel Cadmium).
How To Care For Rechargeable Batteries Cordless Tools
- Keep the battery charged. Running the battery down till its completely drained isn’t good for almost any battery. Even NiCd and NiMh batteries that have the (alleged) “memory effect” only need to be completely discharged once in 20-30 days to counter this problem. (more about “memory effect” in this post).If your woodworking tool has a Li-ion battery you do not ever need to fully discharge it as these batteries do not suffer from memory effect. Partial discharges are good for Li-ion batteries. Charge them whenever you get the chance and preferably before they fall below 20% charge.
DO NOT recharge batteries if you have used them for just a little while. At least don’t do this often. Li-ion batteries go through the maximum fatigue during the last 5-10% of their maximum charge. More about this later.
- Discharge The Battery Regularly. In other words, use the tool. Just as important as keeping the battery charged is keeping those electrons moving inside the batteries. Batteries do not like to be left idle for long periods of time. If you are not going to use the tool much, buy a corded model instead or store the batteries the right way. We will get to “right battery storage techniques” later in this post.
- Charge fully. Most batteries need to be charged fully to keep them healthy. Li-ion may be an exception to this. They prefer partial charges and dis-charges. No harm done in fully charging it as well if you want the longest run-time on a single charge.
- Protect the battery. Keep it cool and dry. Do not drop it or give it hard bumps. Li-ion batteries are particularly susceptible to high temperature and hard shocks. Do not leave your batteries in a hot place, inside or outside the tool. Do not get it wet.
- Do not deep discharge your battery. If the power tool starts showing signs of weakening in power, charge it up or use a 2nd backup battery. Do not run down the battery till its drained. Hard use of your woodworking tool may be unavoidable at times. But avoid deep discharges whenever you can.
- Adjust tool power settings. Your cordless woodworking tool may have settings for variable speed and power. Using a lower setting when its sufficient for the job will run the tool for longer for every charge.
- Do not overcharge. Most modern woodworking tools have chargers that will not overcharge a battery. Some are designed specially so that you can leave your NiCd and NiMh batteries on them to keep them charged. Unless the user manual tells you differently, do not leave your batteries on the charger once they are charged. Overcharging can damage the battery and reduce its life.
Note: Extend Life Of Li-ion batteries upto 3 Times
If you always charge your Li-ion battery to only 80-90% of its full capacity, you will increase its life 2-3 times. The life of a battery is determined in ‘cycles.’ A complete charge and discharge of a battery makes one cycle. A 50% discharge and charge makes half a cycle, and so on and forth.
So let’s say the life of a particular Li-ion battery is supposed to be 500 cycles, after which its ability to hold a charge will decrease dramatically. By following the above trick, you can extend the life of this battery to 1000-1500 cycles.
How To Store A Battery When Not Using It
First of all, it’s best to keep using the battery. Use your tool at least once in 20 days. However, this is not always possible. Storing the battery the right way is also essential to its health and overall life.
When putting away cordless tools for a long time:
- Put the battery in a cool and dry place and away from dust.
- Put it in the original plastic case it came in. Put in a box or wrap it in a soft cloth.
- Do not store Li-ion batteries fully charged or dis-charged. Store them at 30-40% charge level. Do the same for Nickel based batteries, though it does not make too much of a difference as they lose their charge fairly quickly anyway. Many manufacturers will recommend that you discharge your Nickel based batteries completely before storage. Follow the manufacturers instruction if your battery comes with them.
- Fully charged NiCd batteries lose charge quickly. 20-30% in 24 hours. 10% the day after that and 1% for every day after that. Be ready to charge your NiCd and NiMh batteries after a long period of rest before you can use them again.
- Li-Ion batteries retain their charge for longer. Specially if they are kept in a cool place.
- NEVER put your batteries in the refrigerator or the freezer. This can damage them permanently. Technically, NiCd batteries can be stored at a temperature ranging from -20°C to 45°C. But freezing is still not recommended due to the possibility of ice build up. For a Li-Ion battery 15°C is about the ideal storage temperature. But as long as things are not overtly hot, they should be fine.
Charge Your Batteries Right And Avoid Expensive Replacements
Following the correct charging and discharging methods for your cordless woodworking tools can enhance the life of the battery and save you from buying expensive replacement.
First thing go through the instruction manual on battery care. Not all chargers are the same. For example, DeWatt designs several of batteries and chargers in such a way that the battery can be left on the charger for maintenance and equalization cycles.
How To Charge Li-ion Batteries
- Li-ion batteries like partial discharges. You do not have to wait for them to fully discharge. Top them up whenever you get the chance.
- Li-ion batteries like partial charges. You don’t have to charge them till 100% before using them. In fact, they go through maximum wear and tear and stress when charging 90-100%. By charging them to less than full capacity you will extend their life.
- Li-ion batteries do not like complete discharge. Do not discharge below 20% when you can help it. Stop using the tool when it shows signs of weakening in power and slowing down. Re-charge the battery at this point.
- Do not charge or discharge in very hot conditions like over 40°C.
- Do not leave the battery in the charger for very long after fully charged.
- Discharge a Li-ion battery periodically. They have a shelf life and they stay active for longer when kept in use.
- Charge to 30-40% before storing.
The main difference between NiCd and NiMh batteries is that NiMh does not suffer from the ‘memory’ problem as much as the NiCd version. This means they do not have to be deep discharged.
- Charge the battery when the performance of the tool diminishes. Do not try to drain the battery.
- Topping up and partial discharge is OK. Discharge till the tools starts slowing down once in 20 days or 30.
- Can be kept in the charger to maintain charge if the manufacturer allows it. Check the instruction manual for this information. Many manufacturers make their chargers like this since Nickel based batteries lose their charge very fast.
- Repeated full discharges are OK (till the point where the tool starts slowing down.) They don’t harm the battery. To deep discharge and recondition the battery, take it out at this point and put aside for a day or two.
- Check if your charger has a ‘reconditioning’ or a deep dis-charge mode. This is also know as a ‘maintenance cycle'. The better cordless tools have chargers with the ability to run the batteries through a maintenance mode.
- Avoid charging in very hot locations. i.e. above 40°C.
- Many manufacturers will recommend completely discharging your NiCd and NiMh batteries before storage. Not much point in storing them in a charged state either since they lose their charge pretty quickly.
Best Practices For Long Battery Pack Life
Should I completely discharge my tool battery before charging it?
No. Charge the battery as soon as you feel the power and speed of the tool considerably reduced. Draining the battery completely can damage it. people sometimes try to do this by lying up the trigger switch in the on position.
What is ‘Memory’ and does my wood working tool battery have it?
Memory is a condition in which a battery ‘forgets’ its full capacity to charge and deliver. But this happens in low drain devices. For memory effect to set it, the battery must be drained at the same small rate every time and to the same level i.e. partially. This very rarely happens in wood working tools. The rate of discharge is high since these are high load machines.
Memory effect happens usually in devices that consume less power like cordless phones and electric shavers. Secondly, tools are rarely discharged to the same level on every usage. And the rate of discharge is not uniform. It varies constantly with user handling, intensity of the job and the material it is being used upon.
Therefore, power tool batteries rarely see the occurrence of memory effect. If your tools have Li-ion batteries, memory effect is completely ruled out.
Can I leave the batteries plugged in the charger when not in use?
Read the manual and instructions that came with your tool. Usually it is advisable to take out the battery from the charger after its fully charged. Do not leave it in for more than 12 hours.
If you are not going to use the tool for some time, its better to store the battery in a partially discharged state (40%-50%) in a cool place. However, some manufacturers will allow you to keep the battery in the charger. They have designed their chargers specifically for this purpose for maintenance of the battery.
My battery run time is low. What can I do to improve it?
You can run your battery through a couple of proper charge cycles. If the battery isn’t damaged or beyond its usable life span, this should help increase the run time of your cordless wood working tool.
- Discharge the battery by using the tool till it begins to slow down substantially. Do not completely drain it. Do not tape the trigger switch in ON position.
- Leave the battery out of the tool for a couple of hours till it cools down.
- Charge the battery for a full 8-12 hours in a cool place. Repeat this process 2-3 times.
- If your battery still doesn’t show any improvement in run-time, consider buying a replacement.
Does ambient temperature effect the batteries?
Yes it does. Batteries stored in hot places lose their charge quickly as well as their capacity. Using a tool in too hot or too cold (4°C to 30°C is ideal) can reduce its capacity.
Similarly, a battery being charged in extremities of temperature many not take the charge fully and also suffer from reduced run-time. The reason is that when a battery is being charged or discharged, there is a chemical process happening inside the battery.
Heat and excessive cold interferes with this chemical reaction, sometimes bringing about changes in the battery chemistry that last for good.
How do I dispose off dead batteries?
Never throw them in the bin. Always recycle them. Check your user manual. Many major tool manufactures support and are a part of a recycling program. You may be able to recycle your battery through them. Check with the store you bought the tool from. Look through the yellow pages or online to find the closest recycle center.