Skip to content
Grow In Backyard
Decor

Is It Worth Replacing Batteries in Solar Lights? Almost Always

A rechargeable cell is the first thing to fail in a solar light and often costs a tenth of a replacement unit. Check the panel and switch first.

By Zakaria 2 min read Save to Pinterest — opens Pinterest in a new tab
A square-topped garden lamp head on its post against autumn foliage
Photo: Ralphs_Fotos, Pixabay Content License, via Pixabay
On this page

Almost always. The rechargeable cell is the first thing to fail and usually costs a small fraction of a new light. But check the panel and the switch first — a dirty panel is the most common fault of all.

Diagnose before you buy anything

This table answers the question on its own
SymptomLikely causeFix
Bright at dusk, dead in an hourWorn cellNew battery
Dim all nightWorn cell or dirty panelClean panel, then battery
Nothing at allSwitch off, or corrosionCheck switch and contacts
Works after rain, not in dry spellsPanel filmClean the panel
Nothing after new cell + clean panelPanel or circuit failedReplace the unit

Clean the panel first, every time

A film of dust, pollen or hard-water residue cuts charging dramatically and is the single most common cause of a solar light underperforming. Warm water and a soft cloth. Do this before spending anything.

Choosing the cell

  1. Open it and read the existing battery. Chemistry and voltage must match.
  2. Most are AA or AAA NiMH at 1.2 V. Some use 18650 lithium; older ones NiCd.
  3. 600–1,000 mAh suits most garden lights. A much bigger cell will not fully charge from a small panel on a short winter day — that is money wasted, not extra runtime.
  4. Scrape any corrosion off the contacts while it is open.

Never fit alkaline cells

Alkalines are not rechargeable, and the light will try to charge whatever is in it. They leak, and occasionally rupture — and leaking alkaline corrodes the contacts and destroys a light that was otherwise fine.

Making them last

  • Switch them off over winter if you can. Short dark days mean the cell never reaches full charge and discharges every night, which is hard on it, and cold cuts capacity further.
  • Better still, bring them in, stored cool and dry, with a charge every couple of months.
  • Site them where they actually get sun. A light under a hedge or in permanent shade will chew through cells no matter what you fit.

Common questions

Is it worth replacing batteries in solar lights?

Almost always, because the rechargeable cell is the component that wears out first and it typically costs a small fraction of a new light. Solar light batteries are usually standard AA or AAA NiMH cells that last around one to two years of nightly charge and discharge cycles before their capacity falls far enough that the light fades within an hour. Everything else in the unit — the LED, the panel, the circuit — normally has years left.

What batteries do solar lights use?

Most take a single standard AA or AAA rechargeable NiMH cell at 1.2 volts, and a few use a 18650 lithium cell or an older NiCd. Open the unit and read the cell before buying, since the chemistry and voltage must match. For NiMH, capacities between about 600 and 1,000 mAh suit most garden lights well — a much larger capacity will not fully charge from a small panel on a short winter day and is money wasted.

Can you put normal batteries in solar lights?

No. Alkaline batteries are not rechargeable, and a solar light will attempt to charge whatever is in it, which can cause the cell to leak or in the worst case rupture. Leaking alkaline corrodes the contacts and destroys the light that was otherwise fine. Use rechargeable cells of the chemistry the unit was designed for, and if the original is unreadable, NiMH at the same size and voltage is the safe assumption for a standard garden light.

My solar light still does not work with a new battery. What now?

Check three things in order. Clean the panel, because a film of dust, pollen or hard-water residue cuts charging dramatically and is the single most common cause. Make sure the on-off switch is actually on, which sounds obvious and catches a lot of people after winter storage. Then look for corrosion on the battery contacts and scrape it off. If all three are clean and it still fails, the panel or circuit has gone and the unit is finished.

How long should solar light batteries last?

One to two years of year-round use is typical, because they cycle every single day. Lights that run all night in summer and charge poorly in winter age faster than ones in a sunny position. A useful sign of a failing cell is a light that comes on brightly at dusk and dies within an hour or two — that is lost capacity rather than a charging fault, and a new cell fixes it.

Should I bring solar lights in over winter?

It helps, particularly in regions with little winter sun. Short dark days mean the cell never reaches full charge and then discharges every night, which is hard on it, and freezing temperatures reduce capacity further. Switching the lights off and storing them somewhere cool and dry, giving the cells a charge every couple of months, gets more seasons out of them. If you leave them out, at least switch them off.

Backyard Weekly

Know what to plant, week by week

Join the weekly email for seasonal jobs, fixes for what is going wrong, and gear worth buying.

Not ready to subscribe? The planting calendar is free and needs no email.

By subscribing you agree to our privacy policy. Grow In Backyard will never sell your address.

Keep reading