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Thread: solar light review

  1. #11
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    Quote Originally Posted by Chuck(G) View Post
    If the housing of the lamp is cast ('pot metal"), the white powder is likely zinc oxide, leached from the zinc in the metal. Non-toxic--people put the stuff on the face as a UV protectant.
    There's no metal on the housing, it's all plastic. The only thing that may be metal is the LED housing, which can sometimes be machined aluminum that's anodized, but that would be an expensive light if it was.

    I don't think I've ever seen a pot metal solar light. That would be pretty expensive to do compared to injection molded plastic, which is just cents per piece after the mould is made.

  2. #12

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    During Ohio winters, temperatures swing below and above freezing quite frequently.
    Trying to charge batteries at varying temperatures, pressures,voltages and resistances can cause them to vent.

    When I first opened them, the lights appeared to be dry inside
    In the fourth image "image024.gif" I washed off to the dust to see what was underneath.
    When I ran the water, some of the dust and parts of the circuit board came off.
    You can see that parts of the copper traces have decayed.

    After some consideration, I recognize that most inexpensive solar lights are unfit for winter use in northern climates.

    I've no way to compare climate differences.
    Do solar lights fail from different causes in the south?

  3. #13
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    I've got one with the LiFePO₄ battery. Claims to be aluminum-cased. Regular steel pipe clamp-on fitting. Intended for commercial use, but oddly, was only about sixty US clams. Could have been a close-out.

    My wall-mounted LED yard lights are all metal (probably pot metal) cased as well. One type puts the LED arrays behind glass, not plastic. These aren't solar, but AC line operated. Bright suckers.

  4. #14
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    Quote Originally Posted by watlers_world View Post
    Do solar lights fail from different causes in the south?
    There's several failure modes that happen down here in the south:

    1) The crap NiCD battery dies.
    2) Water ingress damages the PCB, battery/battery terminals or corrodes the legs off the LED.
    3) The solar panel dies.
    4) The charging IC can die from high temperature and/or over voltage/current conditions on bright hot days.

    In the rare event the light lasts more than a year, the lens will start turning yellow/brown and go cloudy from UV damage. By this time the crappy (usually NiCD) battery dies. They use the lowest possible rating batteries, usually 300 mAh, but sometimes as low as 150 mAh. The ones with 2/3 AA batteries can be replaced with 600-800 mA NiMH batteries that can last from dusk to dawn, unlike the crap batteries that usually only last a few hours after dusk. Sometimes the cheap crappy batteries are defective and have a super high internal resistance that causes the battery to self-discharge to nothing in just a few minutes.

    The larger lights that use a normal AA or AAA rechargeable battery can be replaced with 1000-2000+ mAh NiMH batteries, which last from dusk to dawn and then some. It can make up for cloudy days where a previous charge will help the light last another night.
    Last edited by GiGaBiTe; September 20th, 2020 at 09:12 PM.

  5. #15

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    NiCads have a serious issue when used more than one in series. If you reverse current them ( one cell finishes before the other ) the depolorizers, that convert the outgassing from charging, are on the wrong sides of the battery. The pressure builds an burst the seal. Within a couple weeks the cell is dead.
    The metal dendrites were always a problem on NiCads. They still are on lithium battery packs for cars. If you've ever seen the packs used in cars, each cell has a fuse wire. If it shorts internally, its fuse will blow and safely remove it self from the rest of the cells.
    Dwight

  6. #16

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    I want to thank everyone for their input on the subject.

    With the smaller solar lights it seems simple enough to discount total failure and just shrug it off as with any impulse purchase.
    However, I really had hoped that these lights might work a bit longer.
    They were somewhat more expensive than their smaller cousins.


    Speaking of light failure:
    As far as I could remember, just about every failed light caused an open circuit.
    However, I've receintly experienced a string of LED light failures.

    If I recall properly, these LED string lights are segmented into sections of 34 LED each.
    If one light should fail, 34 lights go out.
    All 34 are wired in series.
    You would think that this would save the other 33 LED lights.

    The bad news is that these LED lights always short out to zero resistance when they fail.

    Do solar LED lights fail like this also?
    Attached Images Attached Images

  7. #17

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    Many series stringed likes are designed to fail shorted, if the light opens. The wires a feed with a constant current source. If the light doesn't allow current to pass, the voltage across that light will go up until some threshold and then it will short out, keeping the other lights lit.
    Most solar lights usually run in parallel and the light generally fails open.
    Dwight

  8. #18

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    Some plastics become very brittle when they are cold.
    It seems that after they warm back up, they are as sturdy as ever.

    With a sealed battery, it is easy to think of it as venting.
    However, we don't usually think of plastic as having anything to vent or release.

    One can easily notice that the sun causes plastic to break down rather quickly.
    Extremely cold temperature conditions can also accelerate the natural decomposition of plastics.

    Eco friendly plastics are chosen for use because they are guaranteed to break down in a certain number of years.

    Do you think that exposing a LED light to direct sunlight and varient temperatures might decrease its number of useable hours of life?

    In the case of those LED strings, one bad LED causes 33 others to fail instantly.



    Thank you Dwight ,I understand that batteries have series imbalence problems
    which can cause them to vent.

    I noticed that each LED seems to differ somewhat in resistance and light output.
    Also, if I recall properly some types of lights are said to contain some inert gas.

    When LED lights get old do you suppose they also vent bad gas and have imbalance problems?

  9. #19
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    Quote Originally Posted by watlers_world View Post
    Eco friendly plastics are chosen for use because they are guaranteed to break down in a certain number of years.
    Garden lights are definitely not made of "eco friendly" plastic lol. They're made out of ABS, which is one of the worst persistent plastics. ABS doesn't break down into its constituent parts unless it's heated to 750F, which isn't a great idea because the constituent chemicals are carcinogenic.

    Quote Originally Posted by watlers_world View Post
    Do you think that exposing a LED light to direct sunlight and varient temperatures might decrease its number of useable hours of life?
    Extreme temperatures in either direction drastically reduce the life of garden lights.

    Quote Originally Posted by watlers_world View Post
    I noticed that each LED seems to differ somewhat in resistance and light output.
    LEDs should never have any measurable resistance because they're a diode junction. If they do have measurable resistance, they're damaged or defective. Cheap crap Chinese LEDs you find on Ebay, Amazon, etc. are often crap rejects out the back door of some LED factory resold on the grey and black markets, where they find their way to oblivious buyers around the world on unregulated marketplaces like those mentioned.

  10. #20

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    I'm not sure what you mean that LEDs should have no measurable resistance. In back voltage the current should be almost 0, meaning infinite resistance. In the forward direction, it depends on the force voltage of the meter. Different meters often use a different possible force voltage. Most digital meters use a constant current source, set to that the maximum forward voltage is in one of the lower voltage ranges for an open circuit. Typically they will use only a few constant current ranges and then use multiple voltage ranges for scales. On many meters this is 200 mv and 2 v scales. On the next resistance scale they switch the current source and then reuse 200mv and 2 volt. There is no reason that for a meter to not use a higher voltage or higher current combination. Some analog meters can have quite high open circuit voltages. It is the voltage that turns on diodes in the forward direction. It isn't a sharp square edge. it is usually logarithmic as to the current that flows depending on the voltage applied. For you to say, it should show or not show resistance is difficult unless you know the specific meter used.
    Dwight

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