On Tuesday 26 December 2023 at 18:04:51 UTC, Andy Burns wrote:

> A 50W panel would be approx 500x700mm, between november and february,
> would give you a grand total of 8 kWh, so 66 Wh/day, if you want 12 LEDs
> to run 16 hours a day, they need to be about 300mW each (and that's
> disregarding battery losses)

The panel would have to be vertical to pass between the posts that support the gate.
Six lights would be enough.
It's a very dark area, so I think 300mW LEDs might be bright enough. Can you point me to some examples of these?
How do I make it so the lights come on at dusk and go out at dawn? What do I do about voltage regulation?
Bill

On 12/27/2023 8:49 PM, wrights...@f2s.com wrote:
> On Tuesday 26 December 2023 at 18:04:51 UTC, Andy Burns wrote:
>
>> A 50W panel would be approx 500x700mm, between november and february,
>> would give you a grand total of 8 kWh, so 66 Wh/day, if you want 12 LEDs
>> to run 16 hours a day, they need to be about 300mW each (and that's
>> disregarding battery losses)
>
> The panel would have to be vertical to pass between the posts that support the gate.
> Six lights would be enough.
> It's a very dark area, so I think 300mW LEDs might be bright enough. Can you point me to some examples of these?
> How do I make it so the lights come on at dusk and go out at dawn? What do I do about voltage regulation?
> Bill
>

A CdS cell detects dawn.

You've probably seen these sensors at some point in your life.

https://learn.adafruit.com/photocells/overview

The CdS in my carriage lamp, is very slow. You have to hold
something over the sensor for about two minutes, for it to
come on. If a car drives by, the carriage lamp does not
change state.

There are photodiodes and phototransistors, which react quicker
to light sources. All sensors have dark current as a source
of noise.

*******

Reliable batteries, that work in the coldest weather, are expensive.

https://advancedbatterysupplies.co.uk/solar-leisure-batteries/

To run a decent light level, 18 hours a day, and have a battery
source that will stay up for a week without winter sun, that's going
to take a good sized battery, and a set of panels that can
restore a days consumption, in only two or three hours of
good sunlight. If a lead acid battery had 240Ah of capacity,
you can use 60Ah of it, to enhance battery life (which is not
that great to begin with).

The engineering is toughest in winter. That's what all this
expensive excess is about. If the project only had to work
in summer, the project becomes a lot cheaper.

The fairy lights here, have never worked that well in winter.
Usually they're flat in mid-winter and not lighting up. And in summer,
they might run until midnight. That's just to give a comparison
to an "unreliable" solution. Most of the time, your gate would
be unlit with those. They just drain too fast, and cold weather
affects the Lithium iron Phosphate batteries.

*******

Reflective tapes are another item you can use on a gate.
Works with automotive headlights. You cannot use just any product
for this, as people will take your money and give you a
poor quality (low reflection) tape.

https://reflectivetape.info/wp-content/uploads/2011/12/eg_gate.jpg

When the city put up new gates in front of the park (four entrances),
they used aluminium gates rather than steel, and the reflective tape
would knock an eye out. Can't miss it. It was a bit of a departure
from past gates. The tape was likely factory-fitted, to the gate.

Paul

On 28/12/2023 01:49, wrights...@f2s.com wrote:
> On Tuesday 26 December 2023 at 18:04:51 UTC, Andy Burns wrote:
>
>> A 50W panel would be approx 500x700mm, between november and february,
>> would give you a grand total of 8 kWh, so 66 Wh/day, if you want 12 LEDs
>> to run 16 hours a day, they need to be about 300mW each (and that's
>> disregarding battery losses)
>
> The panel would have to be vertical to pass between the posts that support the gate.
> Six lights would be enough.
> It's a very dark area, so I think 300mW LEDs might be bright enough. Can you point me to some examples of these?
> How do I make it so the lights come on at dusk and go out at dawn? What do I do about voltage regulation?
> Bill

You are not trying to light up the area in front of the gate but to make
people aware that there is a possible obstruction in front of them. I
have a couple of discrete LEDs working from 4 off AAA batteries and they
are constantly on for months until the batteries die. I'm running these
LEDS at around 0.2mA (approx 0.5mW) and they easily can be seen from
greater than 5m. With a different supply arrangement (series resistor)
they could be run at 30mA (approx 100mW) and burn out my retina :)

As others have suggested, also use some reflective tape which will be
illuminated by car headlights

Big Clive solar dusk to dawn switching
https://www.youtube.com/watch?v=ycFTxCoNAQk

Big Clive dusk to dawn battery Xmas lights modification
https://www.youtube.com/watch?v=KAm7Bc2AuMg

This time of year plenty of ready made battery outdoor Xmas lights. You
could use these for LEDS. In my experience it's possibly the UV from
summer sunlight will degrade the wiring so maybe additional sleaving or
painting the wire.

Random example of discrete LEDs (data - scroll down)
https://www.ebay.co.uk/itm/152555238306

LDR (Light Dependant Resistor)
http://tinyurl.com/59ws3ccb

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

Paul <nospam@needed.invalid> wrote:
> The fairy lights here, have never worked that well in winter.
> Usually they're flat in mid-winter and not lighting up. And in summer,
> they might run until midnight. That's just to give a comparison
> to an "unreliable" solution. Most of the time, your gate would
> be unlit with those. They just drain too fast, and cold weather
> affects the Lithium iron Phosphate batteries.

It's now possible to buy sodium ion batteries from China: they are much
cheaper per Wh than lithium cells and supposedly work down to -30C, with the
downside that the voltage curve is less flat (4V down to 2V usable range).
Cycle life is better than lithium ion but slightly worse than LFP.

https://www.youtube.com/@JulianIlett/videos
has some videos. Seems like cells are available but commodity BMSes aren't
quite there yet, so you need some hackery.

Theo