Buying Better Batteries: Part One
One rechargeable battery can do the work of hundreds of disposable batteries.
I just want to say one word to you, just one word. Are you listening? Batteries.
With apologies to Buck Henry and Calder Willingham, I can’t help stealing their lines from The Graduate. Forget plastics, batteries are where it’s at.
In this action guide, we’ll explore easy first steps on the pathway to a sustainable energy future made possible by batteries—specifically the small, standard-size, replaceable, and rechargeable batteries you might need for a remote control, flashlight, or smoke detector. In future action guides, we’ll consider how to choose larger batteries, such as battery packs for portable tools and yard equipment. After that, we’ll also delve into making informed decisions about the new breed of “home battery systems” like the Tesla Powerwall, Generac PWRCell, or Enphase IQ Battery.
But let’s start small and work up to the milestone of powering our whole home with batteries. Here are some steps we can take on the trail to battery brilliance:
Master some basic battery facts and concepts that will help us be better battery buyers for the rest of our lives.
Test rechargeable batteries in all our gadgets.
Make a safe switch to non-toxic, long-lasting, dependable, rechargeable batteries.
Organize our home battery collection; take stock of the batteries we have now and the batteries we will need in the future.
Get a decent battery charger today, and keep an eye out for better ones tomorrow.
Weekly Poll: Got Rechargeables?
What Do I Need to Know About Batteries?
Batteries store and release electricity. As the world electrifies, batteries are booming.
Better Living Through Chemistry
To help you make sense of the many new battery choices you and your family and friends will see as consumers over the next few years, I really want you to understand some basic science and battery principles. The chemicals inside a battery make a difference for sustainability—understanding how batteries work at a fundamental level will empower you to make wise decisions as a sustainability champion.
All batteries have at least three layers. In a charged battery, a “positive electrode” wants to receive electrons, an “electrolyte” blocks electrons but allows ions (charged molecules) to react, and a “negative electrode” wants to send electrons. If you provide a path for electrons, such as a metal wire between electrodes, the chemistry of the electrodes will allow ions to react inside the battery and force electrons to flow outside the battery. Once all the available ions have reacted, then the electric flow stops.
Battery Safety
Some (but not all!) batteries contain toxic lead, mercury, cadmium, or cobalt, but the most significant battery risks are the potential to start fires and cause burns, with internal burns especially harmful when children swallow button batteries.
Button batteries are a potential source of serious injury among children, especially when ingested. If lodged in the esophagus, devastating injury can result within hours. Previous studies suggest that button battery ingestions among children aged ≤5 years are increasing.
An estimated 7,032 battery-related emergency department visits occurred annually among children aged <18 years from 2010 to 2019, more than twice the number reported from 1990 to 2009.
Pediatric Battery-Related Emergency Department Visits in the United States: 2010–2019, Pediatrics
As a general rule, if you can take batteries out of a device when it’s not in use, you should. Store batteries in an area where they will not get wet, and ideally in a container that is fireproof. All batteries, when storing energy, have the potential to short out and catch something nearby on fire, but lithium-ion batteries are especially troublesome because the electrolyte inside them is flammable.
It’s a good idea to store non-rechargeable alkaline and rechargeable NiMH batteries in a plastic case, but that is risky with lithium-ion batteries, which can sometimes spontaneously burst into flame and get hot enough to catch plastic on fire. While it’s okay to put dead alkaline or NiMH batteries in the trash, lithium-ion batteries should always be recycled or disposed of as household hazardous waste.
One Way or Round Trip
Some chemical reactions are “one way”—like those in a disposable battery. Once all the ions have undergone reactions in a single-use (“primary”) battery, it’s hard to get them back. Reversing the flow of electrons just heats up the battery rather than reversing chemical reactions to restore ions.
Other chemical reactions are reversible—in a rechargeable battery, ions can easily make a round trip between charge states in the electrodes. If electrodes and electrolytes have the right materials, sending electrons back into the negative electrode (i.e. by sending electricity “backwards” through the battery) sets off chemical reactions to restore ions to a charged state inside the battery.
If a battery does not have the right mix of chemicals in its electrodes and electrolyte, it cannot be recharged. Don’t be fooled by charlatans who claim you can recharge disposable batteries. Trying to recharge a single-use battery after it has depleted its ions simply heats it up, which might cause the battery to rupture or catch on fire.
Volts, Watt Hours, and Other Ratings
When we buy batteries, we need to know the voltage: some devices require 1.5 volts (V), while others need 9 volts. If the voltage is too low, not enough current will flow through the device to make it work. If the voltage is too high, too much current will flow and it might destroy the device.
We also like to know the energy storage capacity of the battery, because that determines how long the battery can power our device. Battery are usually rated by amp hours (Ah) or watt hours (Wh). For small batteries, the storage capacity is measured in thousandths (“milli-”), either mAh or mWh. If we know how many amps or watts our device requires and we know our battery’s mAh or mWh, we can figure out how many hours our battery will last.
When we electrically connect the positive and negative electrodes of a charged battery, the positive electrode acts as a cathode, attracting electrons and producing direct current (DC) electricity, while the negative electrode acts as an anode, repelling electrons and accepting current. The voltage of the electricity depends on the chemicals in the battery electrodes, while the amperage of the electricity depends on how many ions per second can react.
If we connect several battery cells together, it’s important to match chemistries. If we mix chemistries, some cells will be operating at a higher voltage and some at a lower voltage. This mismatch can cause batteries to overheat. If a device takes three batteries, do not put one single-use alkaline battery in with two rechargeable nickel metal hydride (NiMH) batteries. Use three alkaline or three NiMH batteries.
Besides the voltage and the energy capacity, sometimes batteries are rated by the maximum power they can produce and how quickly they lose charge in storage. The “C-rate” of a battery describes how fast it can charge or discharge: the higher the C-rate, the faster the battery can charge or discharge, and the more powerful the battery can be (i.e., the more ions per second can react in its electrodes).
The self-discharge rate is measured in percent per time. In all batteries, molecules in the electrodes sometimes just react on their own, even without an electrical connection. A battery with a self-discharge rate of 5% per month will be completely dead (i.e., all of its ions used up) in twenty months, without powering any load.
Common Sizes and Chemistries
A common shape for a 1.5V battery cell is a cylinder: sometimes the three layers (two electrodes separated by an electrolyte) are rolled up like a cinnamon roll inside a metal or plastic can and sometimes the electrodes are just squeezed in as a paste, with the positive electrode connected to a little metal bump on the top of the cylinder and the negative electrode connected to a metal plate on the bottom of the cylinder. A 9V battery is usually a small box with six smaller 1.5V cylindrical battery cells inside it. “Button” batteries are about the size and shape of a coin. One side of the button is the positive electrode, and the other is the negative electrode.
Most disposable (“single-use”) batteries, sometimes called “alkaline” batteries, have electrodes made from a mix of zinc, manganese, potassium, and graphite. Some non-rechargeable “lithium-metal” batteries have electrodes made from lithium and manganese. The rest of the battery consists of steel, paper, and plastic. In theory, it’s possible to recycle single-use batteries, but in practice it’s often hard to find a battery recycling drop-off that accepts them.
For rechargeable 1.5V or 9V batteries, we have two main choices of chemistries:
Nickel metal hydride (NiMH) batteries, which are rated at 1.2V and can be recharged hundreds or thousands of times.
Lithium-ion (Li-ion) batteries, which are rated at 1.5V and can also be recharged hundreds or thousands of times. These batteries use a lithium chemistry that generates 3.2 to 3.7 volts, but have a built-in battery management system that steps the voltage down to a consistent 1.5V.
How Can I Make a Safe Switch From Disposable to Rechargeable Batteries?
We can save money and prevent waste by switching from single-use to rechargeable batteries. Many of us have a mix of single-use batteries and rechargeable batteries in our homes. I recommend the following steps to make a safe upgrade to 100% rechargeable batteries, which are much more sustainable than single-use batteries:
Make a list of the kinds and number of batteries you need. For example, a wireless keyboard might need two size AA batteries, a headlamp might need three size AAA batteries, and a smoke alarm might need two 9V batteries.
Buy some rechargeable NiMH batteries to test in your devices to make sure they work. If NiMH batteries don’t work, try rechargeable 1.5V lithium-ion batteries. Be careful: some AAA, AA and 9V lithium batteries are not rechargeable, and some rechargeable lithium batteries are 3.7 volts not 1.5 volts. When you buy lithium batteries for use in a device that takes 1.5 V batteries, make sure you get rechargeable 1.5 V lithium-ion batteries.
Once you know what kind of batteries will work in your devices, buy enough rechargeable batteries, plus a few spares, to power them all.
Buy one or two battery organizers (fireproof boxes with molded slots for common battery shapes and sizes) that you can keep in a safe location where young children won’t find them. Gather up all the batteries throughout your household and keep them in your organizers. If you won’t be using a device for a while, take out the batteries and store them in an organizer rather than in the device.
Look for a battery recycling drop-off in your community. If you can’t find one, sign up for a household hazardous waste collection event. Take all of your single-use batteries to be recycled.
Buy a smart charger that works with the types of rechargeable batteries you have.
One important thing to know is that the new 1.5 V rechargeable lithium-ion batteries add sophisticated electronics inside of them, called a “battery management system,” that allows them to control the voltage and current they output. Before this technological innovation, batteries were “dumb”: they could not control the voltage and current they produce. While battery management systems add expense and complexity, they allow exquisite control over the power a battery can deliver.
What’s the Best Way to Charge My Batteries?
The most sustainable way to charge batteries is to use direct solar power. We’re still in the early days of developing consumer solar products, so expect high prices and some performance issues. While we’re waiting for better solar chargers, the most practical and affordable way to charge small batteries (AAA and AA) today is with a smart charger that plugs into 120 volt AC wall power.
For the future, here’s what to look for in a sustainable battery charging system:
A solar module that is not directly attached to the charger. It’s best to put the solar module outside, in full sun, in all types of weather. The charger and batteries, on the other hand, are best kept in a controlled environment indoors. A wire between the outdoor solar module and indoor battery charger can allow 48 VDC electricity to flow between them.
A charger that has its own high-capacity rechargeable 48V battery pack built in. This way, the solar module can charge up the battery pack in the charger whenever the sun shines. Whenever you need to charge a 1.5V AAA, AA, or 9V battery (day or night), you can put the small battery in the charger. The charger can transfer energy from its built-in battery pack to smaller batteries.
A charger that can charge all common shapes and sizes of small consumer batteries: AAA, AA, C, D and 9V.
A charger that can detect, test, and charge different battery chemistries, especially NiMH and Lithium-ion. The display should be easy to read and understand, and the charger should have WiFi and an app so you can see and control what it’s doing by checking your phone or computer.
A computer interface to the charger. As new battery chemistries are developed, we’ll need to update the algorithms to detect and charge those batteries.
There are some okay battery chargers on the market today, but I don’t know of any really sustainable small battery charger available yet. If you do, please let me know!
What’s Still Ahead on the Pathway…
Earlier this year, we explored the pathway to sustainable movement; now, we’re exploring the related pathway to sustainable energy. What are the best ways to save, use, and make energy? Stay with us on the journey to sustainability as we take action to have a positive impact on the world.
References and Further Reading
What are the best batteries and chargers for power tools?, Mister Worker
The best home battery and backup systems (plus how they work), ZDNet
Rechargeable Batteries — compared and explained in detail, Michael Bluejay
Pediatric Battery-Related Emergency Department Visits in the United States: 2010–2019, Pediatrics
Fireproof Battery Organizer, The Rigicase Store
Jelly roll (battery), Wikipedia
What is an Alkaline Battery?, BatteriesPlus
What are Alkaline Batteries?, BatteryGuy
What is inside a battery?, Energizer
Lithium metal battery, Wikipedia
What Can I Recycle?, Call2Recycle
Find a drop-off location near you, Call2Recycle
Nickel–metal hydride battery, Wikipedia
The Best Rechargeable AA and AAA Batteries, New York Times Wirecutter
Lithium AA Battery - Rechargeable vs Non-Rechargeable AA Lithium Batteries, Battery Equivalents
How Can I Safely Dispose of My Waste?, Maine Department of Environmental Protection
The 5 Best AA Battery Chargers, Eneloop 101
Guide 12 + Nomad 5 Kit, GoalZero
The Best Rechargeable Battery Charger (for AA and AAA Batteries), New York Times Wirecutter
11 Best Rechargeable Battery Chargers, Family Handyman