If you've ever wondered about the difference between NiMH vs. NiCad vs. LiIon you're not alone - there are thousands of people out there wondering the same thing as you, and wondering how to make the best decisions for their next power tool or battery purchase.
Here's a question you may be asking yourself: "What is the difference between NiMH and NiCd. How do Lithium Ion Batteries work compared to the others?"
To tackle this question we have to look at the criteria for making the power tool battery decision. And then bring Lithium Ion into the equation to round out the choices when you're making a power tool or battery purchase decision.
According to Building a Better Power-Tool Battery you should be looking at a battery's run time, life cycle, volts and amp hour rating.
Quite simply run time is the amount of work a tool can do before its charge runs out. The higher the AH (amp hours) the longer the run time.
Life cycle is how many times the battery can be recharged during its life time.
Volts will determine work output of the tool. John Sara, cordless product manager for Milwaukee Electric Tool, says "Individuals currently using a 18-volt NiCad battery, should see 2 - 21/2 times more work output from a V28."
The higher the Amp-Hour rating the longer the battery lasts - be aware that power tool batteries of the same voltage will often have different Amp-Hour ratings.
NiMH vs. NiCad vs. Li Ion: Picking What's Right for You
Nickel metal hydride (NiMH) Batteries:
I don't think I could define it better than wiki pedia: 'A nickel metal hydride battery, abbreviated NiMH, is a type of rechargeable battery similar to a nickel-cadmium (NiCd) battery but has a hydrogen-absorbing alloy for the anode instead of cadmium. Like in NiCd batteries, nickel is the cathode.'
Nickel metal hydride (NiMH) advantages:
-- lighter than NiCad
-- 2-3X capacity to equal size NiCad
Nickel metal hydride (NiMH) disadvantages:
-- fewer life cycles compared to NiCad
-- shorter run time
-- performs the worst in cold temperatures, so keep that in mind if you plan to use tools powered by NiMH outdoors in cold weather
-- higher self-discharge level than NiCad
-- voltage drop at near-discharged levels
Nickel cadmium (NiCd) Batteries:
According to Wiki pedia: the 'nickel-cadmium battery (commonly abbreviated NiCd and pronounced 'nye-cad') is a popular type of rechargeable battery for portable electronics and toys using the metals nickel (Ni) and cadmium (Cd) as the active chemicals.'
Nickel cadmium (NiCad) advantages:
-- longer life cycles
-- performs in cold temperatures (perform well to 20°F)
-- lower self-discharge level than NiMH
-- no voltage drop at near discharged levels
Nickel cadmium (NiCad) disadvantages:
-- Heavy, making it harder to use for longer periods of time
-- May suffer from 'Memory Effect' or 'False Bottom Effect' if constantly discharged half-way and then recharged (wiki pedia)
The Lithium ion (Li-Ion) Battery:
The new comer to power tool batteries, Lithium Ion are hot because they have 'one of the best energy-to-weight ratios, no memory effect and a slow loss of charge when not in use,' according to Wiki pedia.
Lithium ion (Li-Ion) advantages:
-- High performance in cold weather - to 0°F - great for winter outdoor use
-- Light weight. You can lift tools powered by Lithium Ion over your head all day.
-- Increased life cycles over NiCad and NiMH, so it keeps going past other batteries
-- more rapid charge times that get you back on the job more quickly
Lithium ion (Li-Ion) disadvantages:
-- less tested than other battery formats - in early stages of development
-- has a shelf life based on life of battery, not related to charge or charge time
-- can sometimes erupt or explode in high heat - hot cars, direct sunlight, etc, or sometimes after tampering. a more dangerous battery than the others
-- permanent damage to battery if stored at too-low discharge level, so be careful and keep these charged well
What battery is right for your power tool decision? Clearly there are many different options, and many different pluses and minuses for each battery type. That's why it's imperative that you come to your purchase prepared with knowledge that will help you make the right decision for your situation.-
It can be easy to dismiss the importance of a high-quality battery in the functioning of your cordless tools. As it turns out, however, a good battery is just as essential to a cordless tool as a healthy armature or motor. Battery technology has significantly advanced since the introduction of cordless power tools; since the development of the Nickel Cadmium (NiCad), power tool batteries have evolved from NiCad to Nickel Metal Hydride (NiMH), and most recently to Lithium Ion (Li-Ion) technology.Nickel Cadmium batteries were the first on the market for cordless power tools and though the technology is older, it is still very reliable. NiCads are less sensitive to adverse temperatures and have a high recharge cycle, meaning they can be charged and recharged repeatedly for a long period of time. NiCads are also less expensive than NiMH and Li-Ion batteries. On the down-side, however, NiCads tend to suffer from battery memory effect. This occurs when a battery can no longer accept a complete charge because it had been repeatedly charged without first being fully depleted. It seems the battery "remembers" how much energy it has discharged, and only wants to accept back that much energy from charger. The element Cadmium is highly toxic making it the most harmful battery to the environment. The NiCad's negative effects on the environment, in fact, cause them to be heavily taxed outside the U.S.A. As a result, many European vendors won't sell NiCad batteries.Nickel Metal Hydride batteries run on a higher amperage than NiCads, because of this, they also have a longer run-time. NiMHs are lighter than NiCads but they are far more sensitive to hot and cold temperatures, in fact, NiMH can't work in below freezing temperatures (32 degrees Fahrenheit and below) and they degrade very quickly in intensely high temperatures (105 degrees Fahrenheit an up). Although the NiMH has a longer run-time than the NiCad it doesn't accept as many charges. NiCad and NiMH batteries do have very similar overall lifespans but NiMH has a larger energy storage capacity.Lithium Ion batteries have a higher energy density than most other rechargeable batteries. A high energy density means that the Lithium Ion has a superior energy to weight ratio storing more energy for their size than most other batteries. Li-Ions have a very slow self-discharge rate meaning they retain their charge for much longer. Most rechargeable batteries significantly deplete as they are disengaged, the slow rate of charge-loss in Li-Ions, however, allows them to maintain most of their charge for longer periods, even on a shelf in your shop or garage.There are many benefits to working with Lithium Ion batteries from their light-weight, to their long run-time. Li-Ions maintain their charge for much longer and have continuous max power throughout their energy discharge cycle. Other batteries consistently loose power as you work. Li-Ions are light-weight, and have a huge storage capacity, this means you now have a lighter, more efficient and powerful battery without the bulk. Lithium Ion batteries are by a landslide the least detrimental to our environment, and for many reasons they are the favorite of most craftsmen.There are, however, some disadvantages to Lithium Ion batteries. Li-Ions are a bit more expensive. The complexities of production (in circuitry) accounts for this price difference. Each Li-Ion also requires a specifically built charger to accommodate that type of battery; this means that chargers are more expensive as well, and aren't universal to all types of Li-Ion batteries. The Li-Ion has a built-in chip that protects the battery from over and undercharging, and ensures it has a longer life. This computer chip, however, doesn't allow the battery to continue accepting charge once its energy level has dropped below a certain point. Once this happens the battery is essentially dead. Li-Ions also rely on this circuit to stay cool. Since Li-Ions loose charge so slowly, and the battery and charger communicate so well together, it's fairly simple to keep Lithium Ions temperate and at a safe charge level.Remember, the quality of the battery you use is just as important as the quality of your power tool. The battery gives the right amounts of energy and finesse to your tools and their working parts.