Solar lights--how often do they need new batteries?

17 years ago

This is our first foray into solar lighting. I just picked up a couple of wall-mountable solar lights for the back of our house. If you go to Home Depot's website and search on item number 79257, you can look at them.

They got a positive review, but the reviewer mentioned it was easy to change the batteries. This is something I never even considered. I'm wondering how often we might have to buy new batteries for them, at $5 a package. Anyone have experience with this?

Here is a link that might be useful: Home Depot

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Comments (12)

ericwi
17 years ago
I don't know how long the batteries will last in your outdoor solar light units. However, I have been using rechargeable NiCad batteries for bicycle lighting for many years. Based on my experience, you can expect the batteries to last 2 years at a minimum. I would not be surprised if you find it necessary to open the unit and clean the contacts/battery ends now and then, with a pencil eraser or similar light abrasive.
RCMJr
17 years ago
.

Oddly enough, in this particular application; you can probably expect a pretty full life from the batteries . . 2 years sounds reasonable. This *assumes* that they are located where they can readily obtain enough sunlight for a full charge most every day.

NiCd batteries LIKE to be fully discharged; and then fully recharged. If you drain them part way, and then recharge . . . they will have less power left to use. This is called "memory" effect; and is common to ALL NiCd batteries. In this application; they run at night 'til the battery is totally discharged. Assuming it gets a full charge the next day . . . you are using them as intended. Full discharge, then full charge. In fact; some NiCd chargers specfically include a full discharge BEFORE doing the charging . . this helps insure a FULL charge and therefore longest life / no of cycles.

I'll suggest that when it IS time to replace them; to use NiMh batteries . . . they are VERY similar to NiCd; except they DON'T have the cadmium ( an environmental bad guy ); are NOT prone to the "memory" effect, but otherwise are virtually identical. They should work fine in your light. The NiCd's should be properly recycled when they're done . . . many places take them . . . to avoid the cadmium getting places where it shouldn't be.

As far as paying $5 for two batteries; look elsewhere . . you can get NiCd's OR NiMh's for less than that for a pair of them . . . .

Bob
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Hello Gumbootmama, I can't believe this thread has gone on for 2 years. I'm curious to know if your system is working for you. I have a few words of encouragement, even if its 2 years late. It sounds like you will be hooked to the grid anyway so the demands on your 12v system won't be constant. I would totally put it in. The cool thing about a 12v system is you can recharge the batteries from many sources. Solar panels of course. And to be realistic you won't get much recharge on grey winter days, but with most modern solar panels you will get some, and if you're only using the power in emergencies the battery will stay topped up, ready for use. Lights and radios don't take very much power at all and when the power goes down, as I'm sure it does up there, battery backup would be great. You could charge your battery from the grid in the winter if you were using it only for emergencies as well. I find it hard to believe you couldn't get power from a small wind turbine, being only a few blocks from the ocean. Especially in Winter. The only concern there is cost and trees. They typically cost over a couple thousand to install, and you usually have to get them higher than the tallest trees. In your neck of the woods that could be over 200 feet. On more of a theoretical note. You may not have sunshine in the winter, but you do have a huge amount of sun energy stored in wood. There is a way to charge your batteries with wood. You use a wood gas generator to power a conventional gas generator. Its not technology that is used very much nowadays. But its old technology. Half the cars in parts of Europe were run on wood gas generators during the second world war. Its even more appropriate technology for remote power generation, because generators typically run at a constant speed. The chemistry behind it is actually pretty simple, but I'll save our readership from that. If anybody is really curious email me. Another option would be to grow a sugar or starch crop and ferment it and distil it for Ethanol and then run your generator off of that. Corn and sugarbeets might work. I think Jerusalem artichoke might be an option as well. You get 1l of ethanol for every 12kg of artichokes. 2000 sq. ft. should give you about 100 litres of fuel. Enough for the winter? You could ferment and distil in small batches in a greenhouse and the extra CO2 and heat would be a real boost to the plants in the fall. This is what we plan on doing at our place. You could of course just run your gas generator on gas. It would only cost you $100 and save you from growing 1200kg of artichokes. Having the 12v is great though, because you only have to run the generator to charge your batteries, not everytime you want power. Water pumping and refrigeration are the big uses of power. Lights and radios use way less so wouldn't be much of a power draw. One more idea. If you only want power for light and radio, and only in emergencies, you could just use rechargable AA NiMh batteries. They are way less toxic to dispose of then their NiCad predicesors. You can order them over the net at about $2 each or less, and a decent charger will cost you less than $50 with shipping. They can be charged up to 1000 times. You could have 10 or 20 fully charged batteries stashed away. Enough for any winter storm. You can even plug them into your car or 12v system to recharge them, or hook them up to a small 3v solar panel. Search for Nexcell on the net. Good luck up there, Sleepybee
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west_texas_peg
17 years ago
I am interested in this type of lighting but my concern is how bright the light is. We bought a solar light before and it was too dim to be of any benefit.
harryo
17 years ago
Solar lights are only meant to accent the area in which they are placed. Expecting high power output from 2 AA batteries is not realistic. We have six of these lights on our property and although they are dim, they do help in providing some light along the walkway they are located.
greenhummer
17 years ago
I replaced my all my wired deck lights with the solar and they have outlasted the wired lights. I always look for the Super Bright White LEDs and make sure the solar cell is covered with glass rather than plastic which will degrade over time (yellow)and become less efficient. The days of the incandescent lamps are numbered as the new technology emerges.
dolle
17 years ago
Four years agoI bought the very cheapest 'Malibu' solar lights that existed at the time. They are ornimental in my beds . I have left them out all winter in the snow,rain, etc and have not as yet changed a battery, so I can say some will go 4 years
lynxville
17 years ago
I get 5 years on mine!
dadgardens
17 years ago
The batteries (NiCad) last about 2-3 years (better quality replacements last longer, NiMh are better than NiCad(Lithium ion are better still, but pricey)). It isn't really a problem with the batteries developing a 'memory' but rather one of number of charge/discharge cycles that kills solar lighting batteries.

The light output is fine for walkways and gardens; but not for area lighting for games etc.
Ernest Ford
6 years ago
I have replaced batteries today in 3 lights, and the instructions say to switch on afterwards. We have bright sunshine at the moment and the lights are on. Presumably if I switch off, they won't come on when its dark.

Help!
mtvhike
5 years ago
Many solar lights, such as yard lights, work on the "always on" principle - that is, during the day the batteries are charged and after dark, the solar panel senses the loss of light and turns on the lights, which stay on until the batteries are discharged.
DavidR
5 years ago
"during the day the batteries are charged and after dark, the solar panel
senses the loss of light and turns on the lights, which stay on until
the batteries are discharged."

What other way would they work? All the ones I've ever seen work that way. Maybe I've missed something.
mtvhike
5 years ago
Well, not that I've seen any, but you could have lights with manual on-off switches. My solar yard lights won't last all night so if could turn off half of them, then turn them back on when the others begin to fail, I could extend my period of lighting. Just a thought...

Solar lights--how often do they need new batteries?

Comments (12)

ericwi

RCMJr

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