SELF-RELIANCE · ENERGY · BATTERY POWER
Battery power, matched to what you actually need.
Every household runs on stored electricity, from the smoke alarm on the ceiling to the phone in your pocket. This guide shows you how to choose, use, store, charge, and safely retire batteries for ordinary days and for the hours or days when the grid is down.
By Dan Whelan, founder of New World Survival
Researched from government agencies, university extension services, and other published sources. See our sources
FROM THE FIELD
Most households get their battery wrong the first time -- not because they bought badly, but because they sized by price and capacity rather than by what they actually needed to run. That pattern surfaces in account after account: a 1,000 Wh unit purchased for "the fridge and some lights" that ran out in four hours because the refrigerator's compressor surge drew far more than its running wattage. This page gives you the numbers to avoid that, starting with startup surge and working from there.
WHERE TO BEGIN
Stored electricity is the quiet backbone of a steady home.
A generator or a solar panel generates electricity while it runs. A battery stores electricity that was made earlier, then hands it back when you need it. That difference shapes everything on this page. A battery is silent, needs no fuel, produces no exhaust, and works the instant you reach for it. What it cannot do is make more power once it is empty. It gives back only what you put in.
Most power outages are short. A storm knocks out a line, a crew restores it in an hour or two, and the lights come back. Some outages, after a major storm or a wide-area failure, last for days. Batteries are the layer that carries a household smoothly across the short ones and buys time and comfort during the long ones. They are useful in an emergency. They are useful on a Tuesday.
What batteries do well
Lighting, phones and radios, medical devices, laptops, fans, small refrigeration, and network equipment. Low and steady loads are where stored power shines.
Where batteries struggle
Anything that makes heat: space heaters, hair dryers, kettles, ovens, and window air conditioners drain a battery in minutes. Those loads belong to a generator or the grid.
No single system fits
A whole-home battery cannot fit in a pocket, and a pocket power bank cannot run a refrigerator. Most households end up with a small stack of the right sizes rather than one big purchase.
THE FRAMEWORK
The battery capability ladder.
Battery backup is a progression, not a product. Each level powers larger and longer than the one below it, and costs more. You do not climb it to the top. You climb it as far as your household actually needs, which for most families is somewhere in the middle. A uninterruptible power supply sits off to the side as a specialized branch, because it solves a different problem: keeping a device from ever losing power for even a moment.
Disposable batteries
Small devices, very long storage, immediate replacement. The AA, AAA, C, D, 9-volt, and coin cells that run flashlights, smoke alarms, and radios.
Rechargeable batteries
The same cell sizes, reused hundreds of times. For the devices you feed batteries to often, plus the tool and camera packs that already came rechargeable.
Power banks
A rechargeable pack with USB ports. Keeps phones, tablets, headlamps, and small USB devices alive through an outage. The single most useful item most households are missing.
Portable power stations
A large battery with real wall outlets. Runs a CPAP, a fan, lighting, a laptop, and a small refrigerator. Recharges from the wall, the car, or a solar panel.
A PARALLEL BRANCH
Uninterruptible power supplies
Not a bigger battery. A UPS switches to its own battery the instant the grid fails, so a router, computer, or medical device never blinks. Runtime is minutes, not days. Its job is continuity, not endurance.
IF YOU NEED SOMETHING NOW
A short outage tonight asks little of you. A good power bank and a headlamp with fresh cells cover most of it. Start at levels one and three.
IF YOU ARE BUILDING CAPACITY
Planning for a multi-day outage, a medical device, or keeping food cold means climbing to level four, and sizing it against your real loads rather than a guess.
THE ONE HABIT THAT PREVENTS OVERBUYING
Start with the device, not the battery.
The most expensive mistake in battery backup is buying the gear first and asking what it runs second. Every good decision on this page starts at the thing you want to keep powered. Answer these seven questions about that device, and the right rung of the ladder becomes obvious.
1.What voltage and connector?
A phone wants USB. A CPAP may want a wall plug or a car socket. A radio takes AA cells. The plug decides the tier before anything else does.
2.How many watts does it draw?
Check the label or a plug-in meter. A phone charger draws about 10 watts, a box fan 50, a full-size refrigerator 100 to 200 while the compressor runs.
3.Does it surge at startup?
Anything with a motor or compressor, a refrigerator, a pump, a power tool, briefly demands two to three times its running watts the moment it kicks on. The battery has to meet that spike or it shuts off.
4.How long must it run?
One night, or three days? Runtime and capacity are the whole game. A device you need for eight hours needs far more stored energy than the same device for one.
5.Is a brief interruption acceptable?
A lamp does not care if it flickers off for a second. A desktop computer or a router does. If a blink is a problem, you are looking at the UPS branch, not a bigger battery.
6.Is it safety-critical?
A medical device, a well pump, a sump pump. Safety-critical loads get planned first, sized with margin, and never left to a single point of failure.
7.How many of these run at once?
This is the question a single-appliance mindset misses. Add up everything you will run at the same time, and add up the total energy across a full day. A battery that runs a fan for ten hours may fail the moment you also plug in a phone and a light. Size against the whole list, not the biggest single item.
Let the calculator do the addition
Working one device at a time hides the two numbers that decide whether a battery carries a household: what everything draws at once, and what the largest motor demands at startup. The Power Needs Calculator totals daily watt-hours, continuous output, and startup surge together, then tells you the battery size that covers them.
Open the Power Needs CalculatorFrom the field · Accounts consistently describe the same undersizing pattern: the capacity number looked right, but startup surge on a refrigerator or sump pump drew three to five times the running wattage and the unit shut off. The surge question in step three above is the one that changes the purchase.
THE NUMBERS, MADE PLAIN
Six numbers tell you everything.
Battery specifications look like alphabet soup, but only a handful of numbers matter, and they relate to each other in simple ways. Learn these once and every product page on the internet becomes readable.
Volts, amps, and watts
Voltage is the pressure, current in amps is the flow, and watts are the two multiplied: volts times amps. Watts are the honest measure of how much work is being done, which is why they matter more than the others.
Amp-hours and watt-hours
Capacity. Amp-hours and milliamp-hours only mean something at a stated voltage. Watt-hours fold the voltage in, so they let you compare a phone power bank to a whole power station on the same scale. Prefer watt-hours whenever you can get them.
Continuous and peak output
Continuous output is what a battery can deliver steadily. Peak, or surge, is the brief burst it can deliver for a second or two. A motor load needs the peak rating to be high enough to swallow its startup spike.
Cycle life and self-discharge
Cycle life is how many full charge-and-drain cycles a battery lasts before it noticeably weakens. Self-discharge is how fast it goes flat sitting in a drawer. Lithium primary cells barely self-discharge; some rechargeables lose a fifth of their charge a month.
CONVERT mAh TO Wh
watt-hours = (mAh × volts) ÷ 1000
A 20,000 mAh power bank runs at about 3.7 volts inside, so its real store is roughly 74 watt-hours. That is the number to compare, not the big one on the box.
ESTIMATE RUNTIME
hours ≈ (Wh × 0.85) ÷ device watts
A 500 Wh station running a 50-watt fan lasts about eight and a half hours. The 0.85 accounts for the energy lost turning battery power into wall-outlet power.
Usable capacity is always less than advertised capacity
Two things stand between the label and reality. Voltage conversion and heat lose 15 to 35 percent of the stored energy on the way out. And most batteries should not be run fully flat every time, which trims usable capacity further. When a number looks generous, assume you will see two-thirds to four-fifths of it in real use.
WHAT IS INSIDE
Chemistry decides behavior.
You do not need to be a chemist. You do need to know that the chemistry inside a battery sets its shelf life, its cold-weather nerve, its safety, and how long it lasts. Here is the whole field on one page, matched to the job each one is good at.
| Chemistry | Rechargeable | Best for | Strength | Watch for |
|---|---|---|---|---|
| Alkaline | No | Everyday low-drain devices, remotes, clocks | Cheap, everywhere, safe | Leaks caustic paste if left in a dead device |
| Lithium primary | No | Smoke alarms, weather radios, emergency lights | Ten-plus year shelf life, strong in the cold | Costs more than alkaline |
| Nickel-metal hydride (NiMH) | Yes | Frequently used AA and AAA devices | Hundreds of reuses, low fire risk | Self-discharges unless it is a low-discharge type |
| Lithium-ion (NMC) | Yes | Phones, laptops, power banks, most power stations | High energy in a small, light package | Fire risk if damaged, pierced, or overheated |
| Lithium-polymer | Yes | Slim electronics, some power banks | Shaped to fit thin devices | Same damage and heat cautions as lithium-ion |
| Lithium iron phosphate (LiFePO4) | Yes | Better power stations, home storage | Very long cycle life, the safest lithium type | Heavier, and weaker output in hard cold |
| Sealed lead-acid (SLA/AGM) | Yes | UPS units, older backup systems | Inexpensive, proven, tolerant | Heavy, short cycle life, dislikes deep draining |
Service life depends heavily on how a battery is used and stored. The figures on any product page describe ideal conditions, not a hot garage or a battery run flat every night.
From the field · Accounts from people who own portable power stations long-term describe one consistent regret: buying NMC chemistry because the capacity number was higher, then discovering the unit tolerated heat and partial charge poorly. LFP handles both, which matters for a unit that sits plugged in for months.
PUTTING IT TOGETHER
A household runs on layers, not one battery.
The families who ride out outages calmly rarely own one big system. They own a small, sensible stack, each layer handling what it is good at. Here is a practical model to build toward, in the order most households find useful.
Disposable cells stocked for the devices that sit idle for months: the smoke alarms, the weather radio, the flashlight in the drawer. Lithium primary where the cold or the shelf life matters.
Rechargeable cells with a charger for the devices you feed often, so you are not buying disposables by the dozen.
At least one good power bank per two people, kept charged, so phones and radios stay alive through any short outage.
A portable power station sized to your real load list, if you need to run essential household devices through a multi-day outage. Pair it with a solar panel to recharge off-grid.
A UPS on the equipment that must not blink: the router, a work computer, or a compatible medical device.
Notice that nowhere on this list is one enormous purchase. The layered approach costs less, fails more gracefully, and grows with you. Buy the flashlight before the battery wall.
SAFETY, IN PLAIN TERMS
Batteries store energy. Respect what that means.
Most battery incidents come from a short circuit, physical damage, heat, or a child reaching a small cell. None of these is exotic, and all of them are preventable with a few habits. The guidance here is drawn from the U.S. Consumer Product Safety Commission and the Environmental Protection Agency.
Coin and button cells around children
This is the most serious battery hazard in a home with young children. A swallowed button or coin cell can burn through a child's throat or esophagus in as little as two hours.[6] From 2011 through 2021 the CPSC recorded 27 deaths and about 54,300 emergency-room injuries from ingested or inserted button and coin batteries.[6]
Keep loose cells and devices with unsecured battery doors out of reach. If you suspect a child has swallowed one, call Poison Help at 1-800-222-1222 and go to an emergency room right away.
Lithium fire and thermal runaway
A damaged, overheated, or short-circuited lithium cell can enter thermal runaway, overheating and forcibly expelling burning contents.[4] Loose cells short easily against keys or coins in a pocket or drawer.
Stop using and unplug any battery or device at once if it swells, grows hot rather than warm, smells sharp or chemical, leaks, hisses, or smokes. Move it to a hard, nonflammable surface away from anything that burns.[5]
Prevent short circuits
Store loose cells so terminals cannot touch metal or each other. Keep 9-volt batteries away from keys and coins; a shorted 9-volt can grow hot enough to start a fire.
Charge with care
Charge on a hard surface, never on a bed or under a pillow. Use the charger that came with the device or a certified replacement; the CPSC has tied uncertified chargers to fatal fires.[5]
Avoid counterfeits
Rewrapped and no-name cells often lack the protection circuitry real batteries carry. Buy from the maker or an authorized seller, and be wary of capacity claims that seem too large for the size.
Mind the temperature
Heat shortens battery life and raises fire risk; a hot car in summer is one of the worst places to leave one. Charging a lithium battery below freezing can permanently damage it.
Handle a leak safely
The paste from a leaking alkaline cell is caustic. Wear gloves, keep it off skin and eyes, ventilate the space, and bag the battery for disposal rather than touching the crystals bare-handed.[5]
Know when to retire one
Any swelling, cracking, deformation, or a battery that no longer holds a useful charge is done. Take it out of service and move to disposal. Do not try to squeeze more life from a damaged lithium cell.
KEEPING THEM READY
A battery you forgot about is a battery you cannot trust.
The point of stored power is that it works when you reach for it. A little organization is the difference between a drawer of live cells and a drawer of guesses.
Keep an inventory
A short list of what you have, in what sizes, and where it lives. You cannot rotate or resupply what you have never counted.
Label the dates
Mark packs of cells with the month you bought them. For power banks and stations, note the date of the last full charge and the last test.
Separate charged, dead, and damaged
Three bins, not one. Nothing wastes an outage faster than reaching for a cell you already used. Damaged cells go in their own container, away from the good ones.
Store at the right charge
Lithium batteries store best around half to two-thirds full, not empty and not stuffed to 100 percent for months. Top a stored power bank or station back up every three months.
Test and rotate
A cheap battery tester tells you in seconds which cells still have life. Use older stock first and push new stock to the back, the way a grocery shelf works.
Mind heat and cold
A cool, dry, indoor spot beats a garage, an attic, or a car. Heat ages every chemistry faster, and a freeze weakens the output you will get in an emergency.
From the field · The most common failure mode isn't neglect -- it's a single charge at purchase and then nothing. Accounts describe reaching for a power station at the first real outage and finding it at twelve percent. A quarterly recharge takes five minutes and is the whole difference.
THE END OF THE LINE
Where a dead battery goes matters more than people think.
A lithium battery tossed in the trash does not vanish. It gets crushed in a truck or at a sorting facility, and a crushed lithium battery can catch fire. The EPA has documented hundreds of such fires at waste and recycling facilities.[2] Handling the end of a battery's life well is a genuine safety act, not a formality.
Rechargeable and lithium: never the trash
Power banks, phone and laptop batteries, tool packs, power stations, and any loose lithium cell must not go in household trash or curbside recycling.[1] Cover the terminals with non-metallic tape, or bag each battery on its own, so they cannot short against each other on the way to the recycler.[3]
Take them to a battery collection site, often found at electronics and hardware retailers, or to a household hazardous waste facility.[1] The chasing-arrows triangle on a lithium battery means it can be recycled at a specialized recycler, not that it belongs in your curbside bin.[2]
Single-use, and damaged cells
Single-use alkaline cells such as AA, AAA, C, D, and 9-volt can go in household trash in most of the United States, though recycling is better where it is offered. California is the notable exception: it treats all batteries as hazardous waste. Check your local rules.[3]
A swollen, leaking, or damaged lithium battery needs extra care. Keep it apart from the others in a nonflammable container, such as a metal can or a bucket with sand or cat litter, away from anything that burns, until you can hand it to a hazardous waste facility. If it is hot, smoking, or you believe a fire is starting, call 911.[2]
GO DEEPER, ONE RUNG AT A TIME
Choose your next guide.
Each level of the ladder has its own detailed guide, with the sizing, the trade-offs, and the buying questions specific to that tier. Start wherever your household is on the climb.
Disposable batteries
Sizes, chemistries, alkaline versus lithium, and how to stock and store cells that sit for years.
Rechargeable batteries
Chargers, cell formats, break-even math, and running a household charging station.
Power banks
Capacity you can trust, USB-C charging standards, sizing, and what a bank truly powers.
Portable power stations
Sizing against your loads, chemistry choice, charging methods, and safe indoor use.
UPS systems
Instant switchover for routers, computers, and compatible medical devices, and how to size one.
Power Needs Calculator
Total your daily watt-hours, continuous draw, and startup surge, then read off the battery size that covers them.
CONNECTED GUIDES
Batteries touch the rest of the plan.
Medical devices in an outage
Planning battery backup for CPAPs, oxygen concentrators, and other equipment.
Power Outage Action Plan
The full first-hour protocol, including when to switch to backup power.
Generators
When battery capacity is not enough: fuel types, sizing, and carbon monoxide safety.
Solar Basics
Recharging a power station from the sun during a multi-day outage.
SOURCES
- U.S. Environmental Protection Agency, "Used Lithium-Ion Batteries." epa.gov/recycle/used-lithium-ion-batteries. Accessed 16 September 2026.
- U.S. Environmental Protection Agency, "Frequent Questions on Lithium-Ion Batteries." epa.gov/recycle/frequent-questions-lithium-ion-batteries. Accessed 16 September 2026.
- U.S. Environmental Protection Agency, "Used Household Batteries." epa.gov/recycle/used-household-batteries. Accessed 16 September 2026.
- U.S. Consumer Product Safety Commission, consumer safety warning on loose 18650 lithium-ion cells, 2021. cpsc.gov. Accessed 16 September 2026.
- U.S. Consumer Product Safety Commission, "Batteries" hazard and voluntary-standards guidance, and 2024 charger fire-hazard warning. cpsc.gov. Accessed 16 September 2026.
- U.S. Consumer Product Safety Commission, "Making Families Safer from Button Cell or Coin Battery Dangers," 11 September 2023. cpsc.gov. Accessed 16 September 2026.