Lithium Ion (Li-ion) Batteries – FAQs
Updated May 25, 2019
As battery-powered yard and garden tools become more common, questions always come up about the batteries. So we’ve provided answers to the most frequently asked questions from our readers. Let us know if there’s anything else you’d like us to cover in these FAQs.
If you’re looking for where to buy specific batteries for common outdoor power equipment brands, scroll to the end of this article for details.
- What is the difference between Lithium batteries and Lithium Ion batteries?
- What does voltage mean (e.g., 40V, 120V)? Are more volts better?
- What does Ah mean?
- Do Li-ion batteries develop a memory? Do I need to recharge after every use?
- Can I use a different brand’s batteries in my XYZ?
- What are the advantages of Lithium Ion batteries compared to other rechargeable batteries?
- Can I leave Li-Ion batteries on the charger?
- How long will it take to charge?
- What are the disadvantages of Lithium-Ion batteries compared with other rechargeable batteries?
- Are Lithium-Ion batteries available in standard sizes like AA , C or D cell size?
- What is the best way to store Lithium Ion batteries?
- Do I need to charge it when I buy it?
- How should I dispose of Lithium Ion batteries?
- Does the battery “die” after a while?
- Can I use a higher voltage battery than the one that came with the tool?
What is the difference between Lithium batteries and Lithium Ion batteries?
There are several important differences. The practical difference between Lithium batteries and Lithium-ion (Li-ion) batteries is that most Lithium batteries are not rechargeable but Li-ion batteries are. From a chemical standpoint, Lithium batteries use lithium in its pure metallic form. Li-ion batteries use lithium compounds which are much more stable than the elemental lithium used in lithium batteries.
A lithium battery should never be recharged, while lithium-ion batteries are designed to be recharged hundreds of times.
What does voltage mean in batteries (e.g., 40V, 120V)? Are more volts better?
Volts are a measure of voltage and refer to the size of the force that sends electrons through the battery’s circuits. It’s sort of like horsepower, except for cordless tools. More volts equal more power available for the tool to use.
Cordless tools that use a higher voltage battery will have more power than those with lower voltage batteries. The question to ask yourself is whether or not you need that amount of power for what you’ll be doing with the tool. For example, if you’ll only be using your cordless string trimmer to trim grass around flower beds, you don’t need 120V (you can practically cut down a tree with some of the new 120V trimmers!).
On the other hand, lower voltage batteries are lighter and smaller, as well as cheaper to buy.
Higher voltage batteries are ideal for users who use the tool often, for longer periods of time and under tougher conditions. They’re also often needed in tools that require more torque or power, such as cordless chainsaws and self-propelled lawnmowers.
The cheaper, lower-voltage batteries are a better investment if the battery operated tool is used only seasonally or rarely, is used for light-duty tasks, or if weight is a consideration.
Some batteries, such as the FlexVolt battery from DeWalt, are designed to automatically change voltage to suit the power requirement of the tool.
What does Ah mean? How does it affect power and/or run time?
Ah is an abbreviation for ampere-hour, or amp-hour. This is the total amount of charge a battery can deliver in one hour. A power tool that continuously draws 1.0A of current will completely drain a 1.0 Ah battery pack in one hour (under ideal conditions).
This means that a 2.0Ah battery pack can power the same tool longer than a 1.0Ah battery pack can, assuming the current flow remains at 1.0A and there are no other differences. Many people simplify this to say that a “higher Ah means longer run time”, although that’s not the whole story.
So a 4.0Ah battery pack will run your outdoor power equipment twice as long as a 2.0Ah battery pack, right? Sometimes, yes. Other times, no. And sometimes it can deliver more than double the runtime. It depends on how the batteries are designed (e.g., running battery cells in parallel vs in series, built-in safety features, venting), as well as tool design (e.g., a trimmer with high and low settings will draw more or fewer amps depending on which setting is used) and environmental factors (e.g., using the battery in high heat will reduce efficiency and run time).
Without more information about the battery, all you can say for certain is that a battery with a higher Ah rating will produce power for longer than a lower Ah battery of the same voltage when used in the same tool and under the same conditions.
If you’re considering a battery for a tool that requires a lot of power or torque to be effective, then a higher Ah battery would be a plus as you’ll get more run time from the battery. If it’s a light-duty tool, then a lower Ah battery will be just fine as it won’t need to draw as many amps to work well (with the added plus of being considerably less expensive).
Do Li-ion batteries develop a memory? Do I need to recharge after every use?
No. While older styles of battery did develop a “memory”, the current Li-ion batteries do not.
Best practice is to place the battery on the charger after each use. That way, you’ll always have a fully-charged battery to work with. Many manufacturers suggest a less than full charge to prolong the overall life of the battery.
Can I use a different brand’s batteries in my tool?
No. Tool companies like to create addicts. The good news is that it pays to become an addict. Manufacturers inspire brand loyalty by selling tools, both with batteries or without. That way, once you’ve bought your first tool – and its included batteries – you can use them on all the other tools from that manufacturer. But only on tools from that manufacturer.
It’s a good idea, then, to make your buying decision based on everything a company sells, even tools that you might not need yet.
What are the advantages of Lithium Ion batteries compared to other rechargeable batteries?
Lithium-ion batteries have several advantages:
They have a higher energy density than most other types of rechargeable batteries. This means that for their size or weight they can store more energy than other rechargeable batteries.
They also operate at higher voltages than other rechargeable batteries.
Lithium-ion batteries also have a lower self-discharge rate than other types of rechargeable batteries. This means that once they are charged they will retain their charge for a longer time than other types of rechargeable batteries. For example, NiMH and NiCd batteries can lose anywhere from 1-5% of their charge per day (depending on the storage temperature) even if they are not installed in a device. Lithium-ion batteries will retain most of their charge even after months of storage.
Can I leave Li-Ion batteries on the charger?
Unless your tool instructions specifically say to store the battery on the charger, be sure to remove it after charging is complete. Overcharging can damage a battery and shorten its life, and not all chargers shut off automatically.
How long will it take to charge?
Li-Ion batteries charge quickly, usually 60-120 minutes depending on the voltage. Check the manufacturer’s directions prior to use.
What are the disadvantages of Lithium-Ion batteries compared with other rechargeable batteries?
Lithium-ion batteries are more expensive than similar capacity NiMH or NiCd batteries. This is because they are much more complex to manufacture. Li-ion batteries actually include special circuitry to protect the battery from damage due to overcharging or undercharging. They are also more expensive because they are manufactured in much smaller numbers than NiMH or NiCd batteries. Li-ion batteries are becoming less expensive and over time we should see their price decrease significantly.
Lithium-ion batteries also require sophisticated chargers that can carefully monitor the charging process. And because of their different shapes and sizes, each type of Li-ion battery requires a charger designed to accommodate its particular size and its particular manufacturer. This means lithium ion battery chargers are more expensive and more difficult to find than NiMH and NiCd battery chargers.
Are Lithium-Ion batteries available in standard sizes like AA, C or D cell size?
No, Lithium-ion batteries are not available in standard sizes.
This could be because it would be too easy for users to inadvertently put them in a charger not designed for Lithium-ion batteries, creating a potentially dangerous situation. If an alkaline battery is put into the wrong charger it might leak or even burst, but a lithium-ion battery put into a NiCd or NiMH charger not designed for lithium-ion might ignite.
Also, because Li-ion batteries operate at a much higher voltage (typically 3.7V per cell) than the 1.2 to 1.5V of most cell batteries, designing a 1.5V lithium-ion cell would be expensive.
What is the best way to store Lithium Ion batteries?
Lithium-ion batteries can hold a charge for many months. It is best to store a lithium-ion battery with a partial or full charge.
Occasionally, if a lithium-ion battery with a very low charge is stored for a long period of time (many months) you may find that its voltage slowly drops to below the level at which its built-in safety mechanism allows it to be charged again. In other words, it’s dead.
If the battery is going to be stored for several months it’s a good idea to take it out and recharge it after a few months. Better yet would be to actually use the battery every few months and then leave it partially or fully charged.
Do I need to charge the battery when I buy it?
Most Li-Ion batteries come with a partial charge. Most manufacturers specify in their instructions how long to charge a new battery before using it for the first time. Usually, this means topping off the charge before first use.
How should I dispose of Lithium-Ion batteries?
Li-ion batteries, like all rechargeable batteries, are recyclable and should be recycled rather than thrown in the trash. They should never be incinerated since they might explode. Most places that sell rechargeable batteries will also accept them back for recycling.
Does the battery “die” after a while?
Yes. You can expect a lithium-ion battery to last from two to three years.
A lithium-ion battery’s lifespan is calculated by charging and discharging cycles. The typical lithium-ion battery has a lifetime of up to 2000 charging and discharging cycles.
Check your individual warranty – the battery should last at least that long.
Can I use a higher voltage battery than the one that came with the tool?
Sometimes, although not a much higher voltage (e.g., do not try using a 120V battery in a tool that comes standard with a 20V battery!). As previously stated, batteries are indigenous to their manufacturers and many are now offering interchangeable voltage options. Keep in mind that higher voltage equals heavier weight and greater cost. Check your tool’s manual for specific guidelines.
Where to Buy Li-Ion Batteries
Below are some of the most common batteries for lawn and garden tools.
- Craftsman V60 2.5 Ah Li-ion Battery (compatible with all Craftsman V60 outdoor tools) – also available as a 5.0 Ah battery
- GreenWorks 29462 G-MAX 40V Li-Ion, 40V 2amp G-MAX Battery
- GreenWorks 29482 G-MAX 40V Li-Ion Charger
- Greenworks PRO 80V 2.0 Ah Lithium Ion Battery GBA80200 – also available as a 4.0 Ah battery
- 40V 2Ah Li-ion Battery with Samsung SDI for All Redback Cordless Garden Tools
- Redback Power 106052 40V 6Ah Battery
- Redback Power 106053 40V 2A Battery Charger
- Redback Power 106051 40V 4Ah Battery
Sun Joe / Snow Joe
- WORX WA3606, 20V 2.0Ah Battery and Charger (for all WORX 20V or 40V dual battery outdoor power equipment)
- WORX WA3578 20V Power Share 4.0 AH Battery (no charger)