Improving solar lighting?

Discussion in 'General Electronics Chat' started by spinnaker, Nov 12, 2009.

  1. spinnaker

    Thread Starter AAC Fanatic!

    Oct 29, 2009
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    I have taken on the project of repairing the solar powered light for our townhouse community.

    So far it looks like it is good news.

    A broken power connector and our property manager who knows nothing about electronics had the polarity wrong on the LED array.


    Seems pretty easy to fix.


    The light has a small 12V battery. Less than 1/2 the size of a tractor or motorcycle battery. These things are hugely expensive. Could I replace this battery with a conventional motorcycle battery or is there something about the design of these batteries that makes them best for use with a solar panel?

    Also there is a street light across the street. Approximately 20 feet and about 30 feet up from from where I could place the panel. The panel would also be facing south. Would I benefit at all from this street light?

    The problem is that the new design of the charger board uses the panel itself as the sensor to turn on the light so this might not work anyway.
     
  2. SgtWookie

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    Very nice of you. :)

    Well, don't beat him/her up too much about it. Although it's always best if you at least try to find the manual before fiddling with things.

    You really should have posted what information you have about this battery; manufacturer and part/model number would be perfect. Adding information about the size of the space available for the battery storage compartment would be even better. Adding information about the light (voltage, current, wattage, manufacturer and part/model number) would be even more complete.

    For the moment, I'm forced to assume that what you have is a deep-cycle sealed lead-acid (SLA) battery. These are designed to be discharged partially over a number of hours, and then fully re-charged. It is best if the battery is sized to not be discharged more than 30% before being recharged; although many installations allow for 50% or more discharge before recharging. The life expectancy plummets under such circumstances.

    Automotive/motorcycle/lawnmower batteries are not deep-cycle; they are designed to give a short burst of raw power to start an engine, and then must be recharged to capacity right away.

    "deep-cycle" batteries have much thicker plates than automotive-type batteries do. They are designed for long, slow discharges. Automotive-type batteries will quickly fall apart if used for deep-cycle applications.

    Conversely, deep-cycle type batteries don't do well in automotive applications; they don't have nearly the plate surface area that automotive-type batteries have.

    The street light produces such a small amount of light compared to the sun that it would have no value as a source of light for charging, or even supplementing the power from the battery when it is discharged.

    The charger board measures the voltage output of the solar array; when it falls below a certain threshold, the light is turned on.
     
  3. spinnaker

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    Thanks again SW,

    The only marking on the battery is UB1250.

    The battery just fits inside the light so I doubt I could get a much larger battery in there but I would not be against placing a larger battery in an external enclosure if it meant I would get the lighting to last longer.

    When it was working, we did not get much life out of those batteries. I suspect that the battery was fully discharged. Should the charger circuit prevent a full discharge from occurring?


    I know nothing about the manufacture of the light. I am trying to get that information from the management company. Hopefully a schematic too.

    Yes I am aware that the charger is measuring the voltage from the solar panel. It would be nice if this voltage was adjustable. When the light was working, I have seen it turn on far too soon in the evening. Perhaps it is just the sensitivity of the panel that is the real issue with the light coming on too soon?






     
  4. spinnaker

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    Also, I assume I can charge this battery with a car battery charger (just to get things going)? If so should I use the 2amp or 6amp setting?

    And I am looking for a 2 pin waterproof connector to replace the existing one. I checked on Jameco but I am not finding anything. Any suggestions?
     
    Last edited: Nov 12, 2009
  5. SgtWookie

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    I performed a Google search:
    http://www.google.com/search?rlz=1C1CHNG_enUS328US329&sourceid=chrome&ie=UTF-8&q=UB1250
    Seems that they're anywhere from around $9 to $16; that's not very expensive. If the property manager has been telling you they're a lot more, I'd want to see the receipts - and take them to the store to see if the receipts match what the store price is. Quite frankly, I think your property manager may be stealing from your association. You need to find out. If it turns out they're a thief, prosecute them.

    They're SLA batteries as I thought they'd be.

    12v @ 5.0 AH is pretty puny, though.

    Ideally, the battery should never be discharged below 70% of full charge.

    Without knowing how much power it takes to run the light, or how much power the solar charger can generate during daylight hours, it will be impossible to know if the charger could keep up with ANY size battery.

    Ideally, it should. Whether it actually has provisions for preventing discharge beyond a certain point is an unknown at this time.

    The manufacturer and model number is a basic necessity at the moment. If the light has been in service for a number of years, it may be just time to replace it with a newer model. Solar panels don't last forever. Lighting technology has evolved quite a bit over the last decade.

    It could be the sensitivity level. It could also be that the solar panel is worn out/dirty/defective, so it's voltage/power output has dropped significantly.
     
  6. SgtWookie

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    Absolutely not. A car battery charger will put out far too much current for the poor little SLA battery to absorb. It may even rupture and spill acid/gel all over the place.

    The maximum recommended charging rate for SLA batteries is 1/8 of the AH rating. In your case, that is 0.625A for 8 hours. If the battery is more than 2 years old, or has been sitting in a discharged state for more than a few weeks, it probably has too much internal damage to be charged and returned to service.

    It would help a great deal if you could find a manufacturer and part number on the existing connector. Without that, it's hard to guess what you're trying to mate to.

    There are an unbelievable number of connectors on the market nowadays.
     
  7. spinnaker

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    I can replace both sides so I don't care who made the original. The original looks like a standard power connector like you find on a PC laptop. I was thinking I would replace it with something that might take a little more abuse. Hopefully water proof.

    The connector is to connect the solar panel to the light fixture (charger board).

    As I said I searched on Jameco but found nothing waterproof.
     
  8. SgtWookie

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    Try Mouser, Digikey, Allied Electronics, Newark.

    I have no idea what your connector looks like, or what your space constraints are, so I don't know what to suggest.

    If it were me, I'd go down to Skycraft Parts & Surplus (which is local to me) and find a mil-spec connector ;)
     
  9. Smoke_Maker

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    Sep 24, 2007
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    Absolutely not. A car battery charger will put out far too much current for the poor little SLA battery to absorb. It may even rupture and spill acid/gel all over the place.

    Sgtwookie, your way to cautious. The battery is junk anyway, how about connecting it to another 12 volt battery to charge it, then discharge the battery with a 12 volt light bulb, do this several times to try and breath some life back into the battery to test the circuit.
     
  10. SgtWookie

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    What you are suggesting could lead to a near-instantaneous explosion of either or both batteries. :eek:

    If the SLA battery is completely dead, connecting a good, charged 12v battery across it would result in maximum current flow from the charged battery to the discharged battery. The only current limiting would be due to the internal resistance of the batteries themselves, the connections to the terminals, and the wiring used to jumper between the batteries.

    If the size of the wiring was not sufficient to carry the current, the wires would get red or white hot, causing a burn hazard. If the wires were lying on the battery case(s), they would be melted, causing property damage.

    If the size of the wiring could adequately handle the current, the heat would be dissipated inside the battery/batteries themselves. Damaged/burned plates, sudden release of large quantities of hydrogen and oxygen gas creating internal pressure, along with internal sparking as interconnects vaporized igniting the explosive gas mixture are very real possibilities.

    On this forum, safety comes first. It is against AAC's policy for any member to recommend a course of action which may result in injury or damage to property, which I heartily agree with.

    I do not knowingly recommend any course of action that may result in injuries or damage, and I attempt to quickly recommend safe alternatives if someone posts an idea which I feel is not safe.

    [eta]
    To make such an attempt safe, a current limiter between the two batteries must be used. Caution must be exercised to not generate a spark in the immediate vicinity of either battery, so as to avoid creating a source of ignition for hydrogen/oxygen gas that may be present.
    The most simple current limiter would be an automotive bulb.
    One of type 89, 90, 97, 98, 214-2, 631, 891, 904, 906, 916, 918, 1555 or 3652 in series would be suitable.

    Reference: http://www.gelighting.com/na/busine...ry/catalogs/downloads/auto_08_index_specs.pdf
     
    Last edited: Nov 15, 2009
  11. Smoke_Maker

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    Sep 24, 2007
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    Your Right, my bad. I have tried a lot of things with batteries and it is NOT a good idea to spread some of these frankinstine methods that could hurt someone that dose not know what the safety risks are.
     
  12. spinnaker

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    Hopefully people are still monitoring this thread. But I really hope they are out enjoying Thanksgiving so I don't expect to get a response right away.

    Anyway, I dragged this project back off the shelf. I thought I had everything working but not sure now.

    The regulator is not charging the battery. How sensitive are outdoor solar panels to indoor lighting? It is a cloudy day here but I used a work light to illumante the panel. The charger has zero volts out.

    The panel is barely putting out 12 V at .6 ma with the load of the regulator.


    Should the panel be doing better than this using indoor lighting?

    I have a small 12 VDC power adapter. I removed the panel and connected the power adapter as input to the regulator. The regulator started charging the battery.


    Do I have a bad panel?


    The panel and light was purchased from this company http://www.siliconsolar.com.

    Their website is pretty horrible. I am having trouble finding anything near the product that we have. They seem more intent on telling how wonderful their products are rather than actually list them.

    The panel measures 1' X 3'. The battery runs a LED light array that us approx 18 x 6.
     
  13. SgtWookie

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    You really can't get a good indication of solar cell output using artificial lighting.

    I fiddled around with a 10+Watt panel a while back; I was lucky to get a couple of mA's out of it using indoor lighting. Outdoors in the sunlight, it would output about 500x that much.
     
  14. spinnaker

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    Thanks Sarge! I was hoping to hear an answer like that. I guess I will have to wait for a sunny day to really test this. :)

    So, is the problem that I am currently (no pun intended :)) with the board is that even though I can get the voltage up, the panel just can't supply enough current to drive the regulator?

    Got another question current related. The wires on the replacement board were WAY too short. I had some wire on hand that was maybe 1 gauge smaller than what was in there and lengthened the wires. Will this make much of a difference or should I go out any buy larger gauge wire? I installed 22 gauge stranded.
     
  15. SgtWookie

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    There just isn't a practical substitute for that big ol' ball o'fire in the sky.

    Yep. Don't know what kind of regulator is in your lights/panels, but even a LM317L regulator needs about 5mA current before it can output a decently regulated voltage.

    With the small amount of current that tiny solar panel will generate, you won't get much voltage drop across 22 gauge wire, unless you have quite a bit of wire in there. 22 gauge wire has a resistance of about 16.2 milliohms (0.0162 Ohms) per foot, or about 85.33 Ohms per statute mile.
     
  16. spinnaker

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    Nope nice aand short piece of wire.

    Thanks again Sarge and have a Happy Thanksgiving!


    BTW - Do you keep all of these specs in your head or do you need to look them up?
     
  17. SgtWookie

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    You're good to go then. :)
    You too! :D

    I have lots of reference material around here, and links to things on the Web - I figure there's no point in memorizing a whole bunch of stuff when I can look it up within a few seconds.
     
  18. Audioguru

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    Dec 20, 2007
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    Here in Canada we celebrated Thanksgiving weeks ago.
    I don't know why we have different dates. Maybe because our trees dropped their leaves weeks ago and yours dropped them yesterday.
     
  19. spinnaker

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    You just made me feel a lot better. I have been a programmer for over 15 years now and I still need to look up functions I use all of the time. :)
     
  20. spinnaker

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    Or just when they decided to set it in each of our countries. I was not aware it had anything to do with fall except being after the harvest season.


    Being from CA, I guess you would not want to be part of my CA/US wall project? Nope not to keep out illegal immigrants but to keep out all of that cold air that comes from CA in the winter. I figure it is going to have to be REALLY high (probably like 30K feet). I haven't figured out all the details yet. I am just the idea man. :)
     
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