There are 3 major types of batteries you will find in your woodworking cordless tool. They are Li-ion, NiCd and NiMh.
Different Kinds Of Cordless Tool Batteries
A modern, expensive woodworking cordless tool from a reputed manufacturer is most likely to have a Li-ion battery. Li-ion is the newest battery technology and the most advanced. While they too have their shortcomings, they have many advantages over the other 2 kinds of batteries. Here are some of the important features of Li-ion batteries.
- Highest energy density. Hold more charge and deliver a higher wattage at lighter weight.
- Run at maximum power for longer as compared to other kinds of batteries of the same capacity.
- Can be partially charged and used without any damage.
- Left alone, they hold their charge for a very period of time, losing only about 5-10% of their charge every month.
- Deliver long life with a high number of cycles. (1500 full cycles is common for a Li-ion battery).
- Are maintenance free for the above reasons.
- Perform well in colder temperatures.
- Are relatively more environment friendly.
- Have advanced circuits to prevent undercharging, overcharging and over heating.
The main reason why not all tools and manufacturers support Li-ion batteries is because they are the most expensive. They also do not perform well in hot temperatures and tend to heat up when used in high drain woodworking cordless tools.
Another thing to keep in mind when buying tools with Li-ion batteries is the quality. Just because its Li-ion doesn’t mean that the battery is necessarily good. There are only a handful of Li-ion cell makers that mostly all reliable manufactures use in their power tools. These are Panasonic, Sony and Samsung. Buy a battery pack that has the cells from preferably one of these 3 companies.
Nickel Cadmium Batteries (NiCd)
These batteries have been the most widely used batteries in power tools. Their main plus point being their low cost. These are the main features of NiCd batteries.
- They are the cheapest batteries to manufacture.
- They are sturdy and do not get damaged easily.
- Perform well in wide range of temperatures.
- Have a reasonably high battery life. (Approx. 800 complete charge cycles.)
- Can be stored for a long period of time in a completely discharged state.
NiCd batteries have a few shortfalls due to which they are not considered the ‘ideal’ battery for power tools though many still continue to use them.
- They have a fast discharge rate. They can lose 20-30% of their charge within the first 2 days and then 30%/month thereafter. Many manufactures design their chargers so that the batteries can be left in them and kept fully charged to counter this kind of a rapid loss. The battery also goes through maintenance and equalization cycles when kept plugged in like this.
- They are heavier than Li-ion batteries.
- They have lower energy density than Li-ion.
- Do not deliver constant power but get progressively get weaker as they are used .
- Can suffer from ‘memory effect.’ However memory effect is not felt in woodworking tools in most cases. More about memory effect in a bit.
- Have a maximum capacity of 2.4Ah.
- Contain a highly toxic heavy metal, Cadmium, that makes them an environmental hazard, difficult to dispose off properly and recycle.
Nickel Metal Hydride (NiMh)
Before the advent of Li-ion batteries, NiMh batteries were believed to be the successor to NiCd batteries. It was thought they addressed all the woes that plagued NiCd batteries. However, this did not come to pass.
They addressed some of the disadvantages like they were lighter, less prone to memory effect and were less toxic. But their disadvantages stopped them from becoming popular in cordless power tools. These are their shortcomings.
- Deliver fewer charge cycles than NiCd, which means a shorter life.
- Performance dwindles in colder weather.
- Have a fast rate of discharge rate, sometimes higher than NiCd when left unused.
- More expensive than NiCd without too many benefits to outweigh that cost.
- Also lose power consistently during use, just like the NiCd batteries
The Memory Effect
This is a defect that NiCd and NiMh, to a lesser extent, are supposed to suffer from. Let’s say a battery is repeatedly discharged to about 50% and then fully charged again. This happens again and again.
The ‘memory effect’ says that the battery eventually forgets its own full capacity to discharge, or it only remembers delivering 50% of its full capacity. It begins to supply only that much power that it remembers from its last discharge.
There are 2 things to know here. For a memory effect to set in, the battery must be discharged at the same rate repeatedly, and to the same level. This almost never happens with woodworking power tools. The amount of power drain on the battery varies a lot according to the job intensity.
Secondly, to counter the memory effect it is only required that the battery be used up and then fully recharged a few times. This too happens frequently with power tool usage. So all in all, you do not need to worry about memory effect in your cordless wood working tools too much.
Sometimes there is an option to pick up the same tool with a choice of different kinds of battery packs. So which one should you choose?
What Kind Of Battery To Choose In Your Portable Woodworking Tool
I would say that depends totally upon your usage.
- Li-ion batteries are probably the most hassle free. They are light, deliver high and constant power and can be charged at will. They lose charge very slowly, they charge fast and can be used partial charges. They deliver the maximum no. of charge cycles, i.e. the longest battery life.
- NiCd batteries save the purpose adequately if you are using the tool frequently. They get discharged on long storage so you need to charge them for several hours before you can use your too. If this is not a problem, NiCd can be a good choice as well. They are heavier than Li-ion, lose power during use. But on the upside, they are much cheaper than Li-ion batteries and have a decent life.
- NiMh batteries are not very popular in tools since they are more expensive than NiCd and do not offer those many additional benefits. They are lighter than NiCd but have a shorted life span.
Technology is constantly improving and batteries are getting better. Newer NiMh batteries have a lower discharged rate, come with fast chargers and are cost effective. A lot of work is being done in the area of Li-ion batteries and they are getting more advanced.
Just remember your work needs and match them to the right tool. For example, Li-ions work well in the cold as well, NiMh does not. Similarly, NiMh can take higher temperatures, Li-ion cannot without suffering in some way.
Li-ion Batteries Are Becoming More Advanced And Popular In Cordless Tools
Modern tools are probably shifting in their preference to Li-ion batteries since they are the most maintenance free. However, certain high current wood working tools still require a NiCd/NiMh battery. Regardless of the technology you choose, there are simple things you can do to get the best out of your woodworking cordless tool.
Get The Best Out Of Your Cordless Tool Battery
- Always use the right battery, charger and power tool combination. Using an incompatible battery can cause damage to the battery itself, the power tool and even cause a personal injury.
- When you first buy a tool with a NiCd battery, its likely to be complexly discharged. Nevertheless, you will need to charge and discharge the battery 3-4 times before it start delivering its full capacity. This is known as ‘priming’ the battery. All NiCd batteries need it as it ensures that all cells in the battery charge up fully.
- Stop using the cordless tool if they battery gets hot. Wait for it to cool down. An overly and often hot Li-ion battery might suggest that there is some internal damage. Stop using it further without having it tested. Heat can damage all kinds of batteries but Li-ion are more susceptible.
- Recharge the battery when the performance of the tool declines. Do not force the tool to work beyond this point. Doing so might damage the battery irreversibly.
- Do not try to ‘recondition’ a Li-ion battery by draining it complexly as you would with a Nickel based battery. Doing this only damages a Li-ion battery and reduces it’s charge capacity.
- If your battery happens to fall hard have it checked before using. Li-ions are particularly sensitive to hard bumps. NiCd are much more hardy.
- Avoid using the power tool in extreme weather conditions, especially heat. Check the instruction manual. Usually anything above 40°C is usable for operating a tool with a Li-ion battery. Li-ion’s handle colder weather better than Nickel batteries and deliver a longer charge.
- Follow the charging and usage instructions that come with the tool or the charger.