Re: Cabochon fairground lights wanted.
- From: mroberds@xxxxxxxxxxxxxxxx
- Date: Mon, 01 May 2006 10:15:46 GMT
Clive Mitchell <bigclive1@xxxxxxxxxxxx> wrote:
In message <1146427295.137612.214600@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
fredtoad@xxxxxxxxxxx writes
The choices of power that i Have are two 85ah leisure batteries and a
small suitcase kawasaki generater. The carnivals run for about two
hours. I just wondered if used a chaser unit/flip flip would that take
less to run as not all of the bulbs are on at the same time.
A flip flop style flasher would halve the load, but it would have to be
beefy for the low voltage high current DC load.
What you could do is wire one string of about 30 to 35 caps (36 to 42 W)
to the output of a two-terminal automotive turn signal (indicator) flasher.
Then, connect the coil of one or more automotive type relays in parallel
with these caps. Run the relay contact common to the battery, and use the
NO and NC contacts to flash additional strings of caps. Typically these
relays are rated at 30 A, so you may only need one relay.
The relay you want is about a 1" black cube, possibly with mounting tab,
with five 0.25" blade terminals labeled 85, 86, 30, 87, and 87a. If it
doesn't have these numbers, it's not the right kind of relay. 85 and 86
are the coil, 30 is the contact common, 87 is open with the relay off,
and 87a is closed with the relay off. Note that there is a variation on
this with only a normally-open contact; on this one the 87 and 87a
terminals are tied together.
You probably have too much load, overall, to run the whole thing from
one turn signal flasher. Even the "heavy duty" ones that are designed
to flash all the lamps on a big trailer only go up to 200 W or so. These
flashers will flash at 1-2 Hz, depending on load (which also depends on
battery voltage).
Another option would be to just use several turn signal flashers with
anywhere from 15 to 60 caps on each one. The pattern will be totally
random, but your entire lighting "controller" will probably cost less
than US$20.
For a load of 300 caps at about 1.2W each you would be talking 360W
divided by 12V equals 30A. A fully charged 85Ah battery would
theoretically run the static lights for two and a half hours.
I would estimate the practical limit to be closer to two hours. If that
85 Ah capacity is quoted at the 20 hour rate (fairly common), it will be
something more like 60-65 Ah at the 2 hour rate; this would support a
30 A draw for 120 to 130 minutes. This is to 10.5 V at the battery
terminals.
I agree with Clive that the batteries are probably a better way to go
than the generator. Around here, plastic battery boxes are available
pretty inexpensively (less than US$10) from RV (caravan), trailer, and
boat shops, and these provide good protection against acid spills,
shorting the battery terminals, etc. I also agree with his earlier
suggestion of fusing things; if you can't get an official fuse panel,
a wad of automotive-type inline fuse holders hanging off of the positive
terminal of the battery is inelegant, but safe and cheap. If I was
doing this and just wiring the caps straight to the battery, I'd probably
split the load into something between three and six circuits, with an
equal or very nearly equal load on each. For three circuits, each one
would have 100 caps and a 20 A fuse; for six circuits each one would
have 50 caps and a 10 A fuse. If you use an official lighting controller,
it may have its own fuses; if there is no fuse on its input, something
like a 40 A to 60 A fusible link between the battery and the controller
may be a good idea.
I hope this helps!
Matt Roberds
.
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