How I picked these: how they work, specs and buyer reviews. I haven't owned every one of them.
What to expect
- "Wind-up" usually means "rechargeable by hand". The crank charges a battery inside. The battery runs the radio or light. When that battery is worn out, the crank can't save it.
- Rechargeable batteries age. Even unused, a lithium or NiMH battery slowly loses capacity over the years. Left completely flat in a drawer, it can stop taking a charge at all. Expect years, not decades.
- Cranking is slow work. A minute of cranking gives a short spell of use, not an evening. They're backups for power cuts, not everyday gear.
- Truly battery-free torches exist, with a catch. A squeeze torch with no battery lights only while you squeeze, and for a moment after. Stop squeezing and it goes dark.
- No crank radio is battery-free. The only radio that needs no power source at all is a crystal set. I have a guide to building one.
Why these picks
With no storage inside, there's nothing to wear out or go flat. It's the one design here that will still work after twenty years in a drawer, as long as the gears survive.
A crank radio still earns its place. In a long power cut, it charges from your arm or the sun. Just know it has a battery and look after it.
A radio needs a steady supply. Cranking is uneven, so the sound would wobble and stop every time you paused. The battery smooths that out. That's why there's no battery-free crank radio.
Some torches store charge in a supercapacitor instead of a battery. A capacitor survives far more charge cycles than a battery, but it holds much less and runs down within minutes to hours.
If the battery is a standard size, like AA rechargeables or an 18650 cell, you can swap it when it dies. A battery soldered inside usually means the whole thing is finished.
"Wind-up", "dynamo" and "no batteries needed" are used loosely. The spec list tells the truth. Section 3 shows what to look for.
How it works
Every one of these has the same first stage: a small generator, often called a dynamo. Magnets and coils of wire turn past each other, and that makes electricity. What happens next is what matters.
- Dynamo. Turns your movement into electricity. Its output often swings back and forth in direction.
- Rectifier. A few diodes, which only let current flow one way. They turn the back-and-forth output into one direction so it can charge a battery.
- Storage. A rechargeable battery (lithium or NiMH) or a capacitor. This is what lets the light or radio keep running after you stop cranking.
- The load. An LED, or the radio's circuits and speaker.
A squeeze torch skips the storage. Each squeeze spins a small flywheel through gears, the flywheel keeps the dynamo turning for a moment, and the LED shows it. Some squeeze torches add a capacitor or small cell to bridge the gaps, so check.
How to tell from a listing
| If the listing says | It means |
|---|---|
A capacity in mAh, e.g. "2000mAh" | It has a rechargeable battery. mAh (milliamp-hours) is a battery size. |
| "Li-ion", "lithium", "NiMH", "18650" | Battery inside. 18650 is a standard cell size, which is good news: it can often be replaced. |
| "Phone charging" or "USB output" / "power bank" | Battery inside. It can't charge a phone without one. |
| "Solar" | Almost certainly a battery. The panel needs somewhere to store what it collects. |
| "Charge via USB" | Battery or capacitor inside. |
| "Lights for X minutes after cranking" | Storage inside. Minutes or hours of light after you stop means a battery or capacitor. |
| "Supercapacitor" / "ultracapacitor" | No battery, but short storage. Long-lived, runs down quickly. |
| "No batteries required" and "lights while squeezing" | Probably truly battery-free. Check the description and questions for a backup cell. |
What to buy
These are affiliate links. If you buy through them I make a small commission, at no extra cost to you. It helps cover the cost of running this site. This is a hobby, not a shop.
Listings change, so check the spec and the battery details on each one before you order.
Torches
Radios
Truly battery-free radio
Set it up
-
Charge it fully on day one
If it has a USB socket, charge it from that first rather than cranking. Then test every function: light, radio, crank, solar.
Why: you want to know it works while you can still return it, not during the power cut.
-
Find out what's inside
Read the manual for the battery type and whether it's replaceable. Write it on a bit of tape inside the battery cover or on the back.
Why: in three years you'll have forgotten, and knowing it takes a standard cell could save the radio.
-
Learn the crank
Try cranking for a minute at a steady pace, then time how long the light or radio runs. Note it down.
Why: that tells you what a minute of cranking is really worth, rather than what the box claims.
-
Tune and note your stations
Find your local and national stations and write the frequencies down. In an emergency, local radio is where travel and power updates come first.
-
Put it somewhere you'll find in the dark
Keep the squeeze torch where you'd reach for a light in a power cut: by the fuse box, or in a kitchen drawer.
Why: a battery-free torch is the right thing to grab first, because it's the one that's guaranteed to work.
Looking after it
- Top up every few months. Put a reminder in your calendar. Crank or charge the radio until it's around half to full.
- Don't leave it totally flat. A lithium battery stored empty for a long time can drop so low it won't recharge.
- Keep it cool. Heat ages batteries fastest. A car glovebox in summer or a sunny windowsill is the worst place. Only the solar panel needs the sun, and only while charging.
- Crank gently. The gears in these are usually plastic. A smooth steady turn charges just as well as a fast one and lasts longer.
- Squeeze torches need almost nothing. Keep them dry and squeeze them now and then so nothing seizes.
Common problems
| What you see | Likely cause | Fix |
|---|---|---|
| Radio dies seconds after you stop cranking | Battery worn out | Replace the battery if it's a standard type. If it's sealed in, the radio may be at the end of its life. |
| Won't charge at all after storage | Battery left flat too long | Charge from USB for a few hours. Some recover. If not, see above. |
| Crank spins but nothing charges | Stripped gear or broken wire | Not usually worth repairing. Use USB or solar charging if it still works. |
| Squeeze torch very dim | Squeezing too slowly | Use quick, full squeezes. It's meant to be dimmer than a battery torch. |
| Squeeze torch handle stiff | Grit or damp in the gears | Keep it dry. Work the handle gently to free it. |
| Radio crackles on FM | Aerial not extended or weak signal | Pull the aerial out fully. Try by a window. |
Safety
- Swollen battery: stop using it. If the case bulges or the battery cover won't close, take the battery out if you can, and don't charge it again.
- Don't put batteries in the bin. UK shops that sell batteries generally take used ones back, and council recycling centres take them too. Lithium batteries in bin lorries cause fires.
- Don't charge from a damaged cable or leave a radio charging on something soft like a bed.
Notes
Battery ageing is the same for every gadget: rechargeable cells lose capacity with time and with use, and faster when hot or left empty. Nothing about a crank changes that. The honest test of any "battery-free" product is to ask where the energy is stored between your last turn of the crank and the light coming on.
Related guides: battery-free shortwave radio, foxhole radio, bike dynamo lights, Morse code without batteries.