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From: Ken James (no email)
Date: Wed Apr 09 2008 - 03:11:05 EDT
wrote:
>>> What is the motivation to create one's own diy leds? At the
>>> 20 dollar mark I cant see a huge savings in making one's own bulbs.
>>>
>
> I would love to find a suitable bulb for my two battery powered anchor
> lights. These are the type that have the big 6v battery w/two screw-cap
> terminals. One is made by Guest, the other I forget who made. Pretty
> much identical except for the type of lamp base (one screw, one single
> pole).
>
> If I could replace the tungsten bulbs with LED's these anchor lights
> would run near forever on those big batteries.
Reply;
Not really. The LED anchor light I mfg ( firststarled.com ) uses about 2
W of power (MKIV model), prob about half what the normal bulb in those
lights uses. The LED light is MUCH brighter of course since it is
brighter than a 25W normal bulb, but it will only go about twice as long
for the power capacity in those batteries as the bulb originally used in
those lanterns before the power is gone...and then you would need to
replace those expensive (now about 5-7$) batteries.
After a few times of that, you could buy a deep cycle battery (50$ for a
HEAVY group 27 if you don't get it at West) and a small solar panel,
then you would only need to replace the battery every five to seven or
eight years! Plus, you would be able to run other device also.
Given that most cruising boats already have a house bank, all that is
needed is to add the small solar panel to make this light self tending
indefinitely for in the long run what will be a much cheaper cost.
Even without a solar panel, at 2 AH per day, the light I make for
example will last for months before taking a house bank to 50% discharge.
> Alternatively, I could
> replace the big 6v battery with 8 AA's and get 12v that way, if it made
> a difference.
>
Yes it would, it would be even more expensive!
> But all the small LED's I have seen are forward facing, and good only
> for flashlights. I need light that has a full 360 plane of light. Don't
> need much vertical arc, maybe 30-45 degs sufficient as the lens would do
> the bending.
>
Sure, that is how LEDs are, they are directional, but when you make a
LED light you take that into account. I use four 140 deg LEDs (Lumiled
K2's for the anchor light) which gives great all-round visibility.
And these LEDs do have more vert spread than needed since they are 140
deg but that is good since that way if your boat rolls a bit, or if
someone is close in fog, you will still see the light with no problems,
and it well even light the deck if it is not too high.
> Anyone seen anything like this anywhere?
>
I do not make 6V led lights and I do not know of any light that would do
for this particular application ...however, dc-dc converters are cheap
and efficient, and so could be uesed to step up 6V to 12V.
But!, a *much more cost effective and simpler solution* is to use a
house bank of 12V and just get a good LED anchor light that is efficient
and will last just about forever. I make some. <G>
Why make life difficult? The best way to get what what it seems that you
want is to use solar, lead acid, and a good LED anchor light with a day
sensor. Easy!
But if you really wanted to, you could replace the bulb in those lights
with a 360 deg LED array you fashion yourself (use copper or brass as a
heat sink, make it a generous size and glue the LEDs on with arctic
silver thermal epoxy) and a readily available in line parallel LED
driver (they can be found on the net cheaply) to convert your lights to
LED operation.
Add the spike and transient/surge protection circuit I mentioned in
previous emails or a similar one (I can supply a schematic) and also you
may be able to add day sensing as an input to the LED driver if you get
one that has an on-off input pin, and Volia!, you have a 6V converted
light.
When you finished, if it worked out well, I am sure others would like to
see the completed project.
But, I doubt if you could do it for less than you can buy a ready made
light in this case. And you would still need to buy costly batteries
every so often.
Truth is, for about twenty bucks you can get a solar LED garden/patio
light that is about as bright as those hanging battery powered lights
you have now, and they won't need to be replaced until the batteries
die, maybe three of four years, longer if they charge well during
daylight. Get one that definitely will go all night without getting real
dim and don't let it get shaded during the day as it has a marginal panel.
Of course these lights are pathetically dim compared to ANY good LED
'real' anchor light. Somewhere like Florida, if you tried to get away
with this you would get ticketed sooner or later. But.
In sum, the best and cheapest method is to buy or build a 12V LED light
that uses your house bank. Such a light could be mounted in your old
halyard hanging fixtures, and BTW halyard hung anchor lights do have
some advantages. -Ken
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