Battery fairy lights run from a small battery pack or a built-in rechargeable cell instead of the mains, so you can hang them anywhere a plug won't reach: a balcony railing, a potted bay tree, a garden arch or a gazebo for one evening. The trade-off is simple. You lose the extension lead, and in return you think about run time, battery type and keeping the pack dry.
Battery sets split into two families, and the label tells you which. Indoor sets are usually IP20: safe to touch, but not meant to meet water, so a steamy bathroom or a windowsill that runs with condensation is already pushing it. Outdoor sets carry IP44 or higher, which means they shrug off rain from any direction. An outdoor set works perfectly well indoors, though its cable is usually chunkier. An indoor set taken outside rarely survives its first wet night.
The same split shows in how they look. Indoor sets favour fine wire that almost vanishes. Outdoor sets usually sit on a thicker PVC cable in green, black or clear, sturdy enough to be tied to a fence and left there.
| Style | Usual length and bulbs | Wire or finish | Best for |
|---|---|---|---|
| Micro wire lights | 1–10 m, 10–100 LEDs | copper, silver or gold wire | jars, wreaths, mirrors, shelves |
| Short 2 m sets | 20 LEDs or so | wire, often on a coin cell or 2 AAs | bell jars, centrepieces, gift boxes |
| Photo peg lights | 2–10 m, 20–100 LEDs | wire or thin cable with small clips | bedroom walls, cards, children's art |
| Cluster and curtain lights | 100–200 LEDs, densely packed | green or clear cable | windows, headboards, a single shrub |
| Outdoor chain lights | 5–10 m, 50–100 LEDs, IP44 | green or clear PVC cable | railings, fences, small trees |
| Festoon-style | 10–20 bulbs | black cable, larger bulbs | a table or gazebo for one evening |
Bigger bulbs draw more current, which is why festoon-style strings on batteries stay short and why a long, bright festoon across a whole garden is a mains job. Battery strings also don't normally link end to end: each one has its own pack.
Most sets take two or three AAs; three AAs give 4.5 V. AAA packs are slimmer but hold roughly half the energy. Coin cells such as the CR2032 only suit tiny decorative sets, and because a swallowed button battery can do serious harm, keep spares well away from small children. Rechargeable NiMH AAs deliver 1.2 V rather than 1.5 V, so the lights look a little dimmer, though most sets cope. If the lights go on every night, a set with a built-in pack charged over USB saves a lot of fiddling.
On fresh alkaline AAs, expect roughly 50–100 hours of light. Leave them on round the clock and that is gone in a few days. Use the timer – usually six hours on and eighteen off, repeating from whenever you first switch on – and the same batteries see you through several weeks of evenings. Dimming helps further, and a remote saves reaching behind the sofa or into a hedge to do it.
An IP44 rating covers the whole set, but the pack is where the screw, lid and cable gland are, so it is where water gets in first. Keep it off the ground and out of plant pots where puddles collect, ideally hung under the eaves or a table edge with the opening facing down. In a cold snap, alkaline cells lose much of their capacity and the lights fade within days. Lithium AAs hold their voltage in frost and are worth switching to for winter.
Battery or solar? Solar strings charge for free but need daylight on the panel. Under a north-facing wall or in December, they often give up before the evening is out. A battery set behaves the same wherever you hang it.
For a bell tent, a festival pitch or a garden party, battery lights make sense precisely because nothing needs to be plugged in or taped down across the grass. Choose an outdoor-rated set even inside a tent, because canvas gets damp overnight, and pack a spare set of batteries. Clip the pack to a guy rope or a tent pole rather than leaving it on groundsheet where dew settles.
Removable adhesive hooks, cable ties and small suction hooks on glass all work without drilling, which matters in a rented flat. Give the battery pack its own hook so its weight never hangs on the wire, and place it where you can change the batteries without a stepladder.
When the season ends, take the batteries out, dry outdoor sets with the pack open, and wind fine wire round a piece of card so it doesn't kink. A green crust on the terminals usually comes off with a pencil eraser. Used batteries go to a battery recycling point, which most supermarkets and shops that sell batteries provide, not in the household bin.
Typically 50–100 hours on a fresh set of AAs, less on AAA or a coin cell. With a 6-hour timer that is a few weeks of evenings. Fewer LEDs, steady rather than flashing light and lithium cells all stretch it further.
Yes. They run at a few volts and the LEDs barely warm up. The bigger risk is a damaged or mismatched battery, so replace the whole set at once. A timer that switches them off saves the batteries as well.
The ones that suit the spot. Look for warm white LEDs, a timer, fine wire for indoor décor or PVC cable and IP44 for outdoors, and a remote if the pack will be hidden.
For shelves, jars and bedrooms, micro wire lights on two or three AAs with a timer are the easiest to live with. Photo peg lights double as a display for cards and pictures.
Usually, yes. NiMH cells run a little dimmer at 1.2 V. If you use the lights every night, a set with a USB-charged pack is the tidier option.
Not normally – each string has its own pack. For a longer run, hang two sets side by side. Linking into one circuit is a mains feature.
The style decides the look; the power source decides how much fuss you put up with. If you would rather never buy another AA, go for a USB-rechargeable set. If the lights only come out for a party or a weekend away, ordinary AAs are perfectly fine. For the wider picture, from festoons to wire lights, see outdoor string lights. If your garden gets plenty of sun, compare them with solar string lights.
