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A solar light that stays dark, or fades soon after sunset, is usually one small fault away from working again. How to fix a solar light comes down to a fixed order: confirm sunlight and the switch, clean the panel, check the sensor by covering the panel, look at the battery contacts and the inside for water, then replace the battery. Replace the whole light only when those steps fail. Stop at the first step that brings the light back.
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How to fix a solar light: the quick answer
Most dark solar lights fail for one of four reasons: too little sun, a dirty panel, corrosion or water at the battery, or a worn rechargeable battery. The first three need only a cloth, a swab and a better position. Do them before you buy anything.
Step 1: confirm sunlight and the switch
Many solar lights have a small switch on the base or under the panel. A light switched off cannot charge or glow, so flip it on first. Then look at where the light stands. The panel needs open sky, not shade from a fence, a shrub or a roof edge. If the light sits in shade, move it to a sunnier spot and check it again after dark.
Step 2: clean the solar panel
Dust, pollen, leaf litter and water spots reduce the light that reaches the cells, and a starved panel cannot fill the battery. Wipe the panel with a soft cloth and plain water, and clear debris from around the light. Avoid hard scrubbing, since scratches on the surface do not wipe away. The best cleaners for solar lights guide covers tools made for this job.
Step 3: check the light sensor by covering the panel
Most solar lights switch on when the panel goes dark. Switch the light on, then cover the panel fully with a thick cloth, or carry the light into a dark room. Three results point to different faults:
- The light glows when covered: the sensor and lamp work, so the problem is charging. Go back to the panel, the placement and the battery.
- The light stays dark when covered, even with a battery you know is charged: the sensor, the switch or the lamp has failed.
- The light glows in daylight or flickers: the sensor may be dirty or faulty, so wipe the panel and check again.
Step 4: check the battery contacts for corrosion
Open the battery compartment. White, green or crusty deposits on the springs and metal tabs block the current even when the battery is fine. Remove the battery, scrape the deposits off gently with a dry cotton swab or a small brush, and make sure the contacts are bright and springy. Bent springs can be nudged back into shape. If a battery has leaked, clean the compartment well before fitting a new one.
Step 5: check for water inside the light
Water that gets past the seal corrodes the contacts and the circuit board. Look for fog on the lens, drops inside the housing or damp in the battery compartment. Open the light, let it dry fully in a warm, dry place, and wipe the parts with a dry cloth. Check the seals and screws, then close the light firmly. If the circuit board is stained or corroded, the light is usually past repair.
Step 6: check or replace the battery
A worn rechargeable battery is a common reason for a light that fades early or stays dark. Read the label on the old battery before you buy, and match three things: chemistry, voltage and size. The common case in garden lights is a 1.2V NiMH rechargeable battery in AA or AAA size, but some lights use other cells, such as lithium-ion or button cells. Never swap one chemistry for another, and do not guess from the light alone. AA and AAA are easy to confuse, so compare the size by eye with the old cell.
For the NiMH case, capacities among replacement batteries run from 600mAh to 2000mAh, and a higher figure means a longer run after a full charge. Fit all the batteries in the light as one matched set: do not mix used and new cells, or different capacities and types. One maker also warns that its 1.2V NiMH cells should not go in products designed only for 1.5V alkaline batteries. New batteries ship only partly charged, with makers stating 30% to 50%, so charge them before first use, either in the light in sun or with a NiMH-compatible charger. Spare batteries in storage should be topped up every 3 months, or every 3 to 4 months by one maker’s advice. Tenergy Solla (on Amazon) states its AA cells are not a replacement for LiFePO4 batteries.
Step 7: replace the light
If a clean panel, a sunny spot, clean contacts, a dry housing and a fresh matching battery still leave the light dark, the lamp, the sensor or the circuit board has failed. At that point a new light is the practical choice. The best solar lights for a deck, the best solar lights for a driveway and the best solar lights for a fence compare current options.
Keep a repaired solar light working
- Keep the panel clean and the light in open sun.
- Check the seals and the contacts whenever you change batteries.
- Check the temperature range on the battery: the EBL and Kruta makers state stable performance from -4 F to 140 F.
FAQ: power away from the grid
Why does my solar light stay dark at night?
The usual causes are a switched-off light, a dirty panel, too little sun, corroded contacts, water inside, or a worn battery. Work through the steps above in order.
What battery does a solar light take?
Read the label on the old battery and match chemistry, voltage and size. The common case is a 1.2V NiMH rechargeable battery in AA or AAA size.
How long do solar light batteries last?
It depends on the cell. The Howardly maker states 500 charging cycles, and the EBL, Kruta and Brightown AAA (on Amazon) makers state 1200. Brightown AAA and Tenergy Solla both state up to 5 years of battery life.
Do I need to charge new solar batteries before use?
Yes. Makers state they ship only partly charged, so charge them before first use.
Can I use a standard battery charger?
For NiMH cells, the makers state a standard NiMH charger works as well as charging in the light. Use a charger made for the chemistry on the old battery’s label.
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