[VAC] Low voltage lights/Intellipower

[Dick and Kris Parins <dkparins@xxxxxxxxxx>]

I have a couple of questions which may be of general interest.  I've been
looking around for some nice 12 volt light fixtures.  The ones that I like
the best are from a low voltage system intended for home use.  I would like
to install some of these 20 watt 12 volt low voltage lights directly into
the 12 volt system of the trailer.  They typically come with a transformer.
Can I bypass the transformer and connect these lights to an
Intellipower/battery operated 12 volt system?  I'm told that a 12 volt 20
watt halogen will produce about as much light as a regular 75 watt household
bulb.  Is this correct?

On a related question, I was given the following formula for sizing an
Intellipower:

To determine the converter rating, the following formula shall be applied to
the total connected load, including average battery charging rate, of all 12
volt equipment:
The first 20 amperes of load at 100 percent; plus
The second 20 amperes of load at 50 percent; plus
All load above 40 amperes at 25 percent.


I'm clear on everything except the average battery charging rate.  How do I
figure that out for a typical marine deep cycle battery?  I'm pretty sure a
40 amp with the charge wizard would be all I would ever need on this little
trailer but I don't want to buy something close to the minimum and regret it
later.  (Not counting the refridgerator which I can look up and the average
battery charging rate I need only about 16 amps.)

Thanks,

Dick
'62 Bambi

PS:  All you folks with more than one Airstream are scaring me.  I may be
getting hooked!  There's a 1971  31 footer for sale down the road that I
can't stop looking at.