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Solar lighting - What do the specs really mean, how much light can I actually expect to get and for how long?


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2 hours ago, Crossy said:

Years ago I bought some solar garden lights.

 

They were not cheap, they were pretty useless.

The panels were tiny, the batteries cheap and the light level would be rivaled by a candle.

They worked well enough for marking the edge of the pond but didn't really provide "lighting".

The glimmer lasted about 8 hours when new.

The batteries finally failed after about 18 months.

 

Since then I've shied off solar lights, until now.

 

On the recommendation of another, well respected, member I bought a couple of these:-

 

Light-1.jpg

 

For 660 Baht how badly wrong can it go?

 

In the box:-

  • A 15W solar panel with a decently long lead and a weatherproof connector.
  • The light itself, nicely made plastic moulding, sadly it's a sealed unit so no easy replacing of batteries
  • Remote control with batteries
  • Bolts for the panel and 4 handy expansion wall fittings.

 

The remote has several modes;-

  • Off - Pretty obvious
  • On - On all the time
  • Auto - On when it gets dark, off when the sun wakes up
  • 3H - On 3 hours **
  • 5H - On 5 hours **
  • 8H - On 8 hours **
  • Dim 
  • Bright

** it's currently unclear if this means it will light for X hours every night.

 

So what performance can I expect?

That 15W panel will generate about 50Watt hours in a reasonable day (our 300W panels are doing about 1000Watt hours).

The 20,000mAh battery (likely 3.3V) can store about 66Watt hours.

So the panel and battery are pretty well matched, good start ????

 

The main unit being sealed means that I can't actually verify the power of the LEDs (no way they're really "60W") so a spot of estimating.

If our 50Watt hours keeps the light on for the specified 8 hours that makes the LEDs 6.25W.

It's also in the right ball park for a 60W incandescent equivalent (explaining where the "60W" comes from).

 

More as testing proceeds.

 

 

 

Your reasoning on the 60W is correct.

The actual Wattage quoted on Led  is Watt equal. The equivalent luminosity for a standard light.

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JD seems to be a renowned brand for solar lighting.

 

I have a set of these on the way for testing. For me they are intended for ambient light within the perimeter, but strange enough the very same light ( same brand and packaging) goes between 249 and 750 Baht on Lazada

 

https://www.lazada.co.th/products/sh-078-solar-cell-solar-light-led-solar-light-led-78-hvshops-i1419208911-s3656346739.html

 

image.png.10c5f92b87d71f427ca206cff748edae.png

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5 hours ago, Crossy said:
  • 3H - On 3 hours **
  • 5H - On 5 hours **
  • 8H - On 8 hours **
  • Dim 
  • Bright

** it's currently unclear if this means it will light for X hours every night.

 

If that setting would indeed work that way, that would be real positive, especially for my purpose, because who needs light within the perimeter after he went to bed. I haven't seen any other lights with that setting yet.

 

Would it be an option to add such a timer to an existing light?

 

The main requirements of course would be, it has to be small and cheap to build.

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On 11/28/2020 at 11:08 AM, Susco said:

image.png.10c5f92b87d71f427ca206cff748edae.png

 

 

My test light has arrived, so I have a few questions.

 

What direction should I point the solar panel? My idea was to have it horizontal, because the sun is most part of the day high in the sky, but I might be wrong.

 

The solar panel has a very matt surface. Is there a film I need to pull off?

 

It says output 5.5V 2.5W, is that the capacity of the panel?

 

Battery capacity is claimed to be 2000 mAh. Any way to check that, as the battery can be accessed.

 

Last but not least. Is there a way to build a small a miniature sized timer, which would shut down the battery output, on a set time after it get activated at night.

 

Let's say 7 hours after the photocell get activated it shut off and stays shut off for the next 7 hours.

 

 

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7 minutes ago, Susco said:

What direction should I point the solar panel? My idea was to have it horizontal, because the sun is most part of the day high in the sky, but I might be wrong.

 

The solar panel has a very matt surface. Is there a film I need to pull off?

 

It says output 5.5V 2.5W, is that the capacity of the panel?

 

Battery capacity is claimed to be 2000 mAh. Any way to check that, as the battery can be accessed.

 

Last but not least. Is there a way to build a small a miniature sized timer, which would shut down the battery output, on a set time after it get activated at night.

 

Let's say 7 hours after the photocell get activated it shut off and stays shut off for the next 7 hours.

 

 

Point your panel south tilted "slightly" (10-15o).

 

Matt surface is normal, nothing to peel off unless it's obvious (none of mine have had film).

 

5V 2.5W will be the panel output.

 

Unless the battery is marked there's not much you can do to verify the capacity. Perhaps compare the physical size with similar batteries on AliExpress?

 

You should be able to knock up a CMOS 555 (the standard 555 uses way too much power) based timer to do what you want without sucking too much of your valuable battery capacity. How to link it into the existing electronics is another matter entirely.

 

 

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40 minutes ago, Crossy said:

Unless the battery is marked there's not much you can do to verify the capacity. Perhaps compare the physical size with similar batteries on AliExpress

Humm BigClive would disagree.
 

The marking on the battery and literature often have very little to do with the actual capacity of the battery. For the average user actually confirming the capacity is, as you say, not very easy, but with a multi meter checking the load at intervals and run time of the light (and math) will get you to within 20% of the real capacity.
 

The weight of similar chemistry cells of the same size is often a reasonable guide to the gross capacity of a cell, in general the heavier the cell the higher the capacity.

 

Of course all of this requires that you actually have the items. 

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5 minutes ago, sometimewoodworker said:

The marking on the battery and literature often have very little to do with the actual capacity of the battery.

 

I can quite believe that fake batteries are out there just like fake flash cards.

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45 minutes ago, sometimewoodworker said:

The weight of similar chemistry cells of the same size is often a reasonable guide to the gross capacity of a cell, in general the heavier the cell the higher the capacity.

 

Any estimate what a 3.7V 2000 mAh battery should weigh on average?

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9 minutes ago, Susco said:

Any estimate what a 3.7V 2000 mAh battery should weigh on average?

 

I wouldn't stress over it unless you don't get the expected performance or the performance tails off rapidly.

 

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On 11/28/2020 at 1:13 PM, Susco said:

 

If that setting would indeed work that way, that would be real positive, especially for my purpose, because who needs light within the perimeter after he went to bed. I haven't seen any other lights with that setting yet.

 

Would it be an option to add such a timer to an existing light?

 

The main requirements of course would be, it has to be small and cheap to build.

 

The time is set on the hand held remote control, point the control at the light and press the desired time you want the light to be on for, the light will flash at you which means it is set for that number of hours, nothing else need be done, I have several set on three hours only, the others I think are all on default Auto setting. 

 

The auto setting is the default meaning it comes on when it is dark and goes off when it is light, no need to use the controller.

 

I am not familiar with the new branding JDJINDIAN all mine are simply JD. 8860 with no S on the end of the cat number, the pictures of the light and the panel look identical to mine though.

 

 

 

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11 minutes ago, Rimmer said:

The time is set on the hand held remote control, point the control at the light and press the desired time you want the light to be on for, the light will flash at you which means it is set for that number of hours, nothing else need be done, I have several set on three hours only, the others I think are all on default Auto setting. 

 

I thought that's what I did to mine last evening (set 3 hours) but the ruddy thing stayed on all night.

 

I'll try with an initial setting of "off" this evening, I think it was "Auto" before I set the time.

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8 minutes ago, Crossy said:

 

I thought that's what I did to mine last evening (set 3 hours) but the ruddy thing stayed on all night.

 

I'll try with an initial setting of "off" this evening, I think it was "Auto" before I set the time.

 

Oh yes,  I think there is a mode to follow and I can't remember what it is, I tried doing with it off and with it on and with it on auto first but it took a few permutations to get it right.

 

Been a long time now but I think one light never did take the time schedule so I ended up moving it somewhere else.

 

Oh and I now have a box full of those ridicules over size brass plugs they give you with the light, I found a couple of six or eight screws with washers to take up the enormous holes works just fine.

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1 hour ago, Susco said:

 

Any estimate what a 3.7V 2000 mAh battery should weigh on average?

That is not possible to say as you haven’t given a form factor of the battery & even if you did you will only get a general guide that a heavier battery is likely to last longer, given that everything else is equal.

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On the subject of  60W incandescent light. The 60W is power consumption and totally unrelated to the amount of actual light as I'm sure you already know. The number to take into consideration is LM (lumens). Decent outdoor lighting would be upwards of 1,000 lm in my opinion which is about what you would get from an 80W filament lamp. If the advert fails to mention how many lumens you get then its not bright enough to do what they say.

 

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9 minutes ago, carlyai said:

So you are saying that no way is this battery 9.9 Ah? 

 

Anything over about 3600mAh in an 18650 format cell is going to be suspect.

 

Of course there's nothing to stop larger capacity packs being made from multiple cells.

 

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On 11/28/2020 at 10:10 AM, colinneil said:

Well Crossy i have similar to the ones you just purchased.

My wife switches them on at around 21.30 and they are still working all night, going off at daylight.

Have been working fine for around 2 years.

My experience too - they work really well but I suspect that battery technology has really matured over the past couple of years.

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I tested my lamps last night for only a few minutes to check the brightness, and that was very satisfying. Since yesterday was a cloudy day, I decided to charge them for a second day before testing the endurance.

 

These are some observations so far,

 

- Brightness is good, even at dimmed all night strength it is sufficient for my purpose.

 

- I watched a customer feedback video, where I noticed he covered the solar panel, and the lights would turn on without covering the photocell. Tried this just here during day time and got the same result. Covering only the photocell would not activate the lights.

Is this normal behaviour?

 

- Shopee and Lazada definitely need to get their act together. The model of the light is SH-078, entering that in the search bar of Shopee gives me 6 results from 225 to 295 Baht. In Lazada  that gives 11 results from 279 to 790 Baht, all with the same package pictured as I received.

 

Now giving SH-078 in Google shows me a Thai website which has a Shopee listing at 160 Baht.

If I click on that listing, I'm taken to the Shopee Thailand website, and from that listing by clicking suggested items at the bottom, I can find at least 6 other sellers selling the product, all below 200 Baht. All listing have the item in stock

So why is it impossible to find these in the Shopee search?

 

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