Re: Ping Neon John Again

On Fri, 17 Apr 2009 19:17:53 -0400, Neon John <no@xxxxxxxxx> wrote:

On Fri, 17 Apr 2009 10:56:31 -0700 (PDT), GingerJools
<gingerjools@xxxxxxxxxx> wrote:

Why can't the inverter feed into the existing ac wiring?

It can.

OK. Good.

1500 watts is only 1500/120 = 12.5 amps. That's plenty for just about
everything except the AC. It isn't practical to run an RV type AC
from batteries but I'm working on an alternative.

Don't need to. I have a swamp cooler which I can use in the dry heat.
Muggy heat, like I get here in southern Ontario isn't a problem 'cause
here I'll be plugged in to shore power.

How do I implement that in my coach? I have sufficient duplex
outlets: 4 inside and 1 outside. I just need to get the "home made"
power into the existing system.

OK. Here's how. First read this:

http://www.neon-john.com/RV/Electrical/Gen_delay/gen_delay.html

That explains how an automatic change-over relay works. You probably
have one in your RV already for your generator. If your electrical
system simply comes alive when you start the genny then you have this
kind of relay. I built mine but you can buy 'em for about $70.

According to the manual, this is what I have. One minute after the
generator fires up, ac power is available. I haven't tested it. When
I've camped with no power, I've used 12V only, running off battery
power. In will test as soon as I visit after May 1.

To make the inverter automatic, you simply buy another relay and
connect it in AFTER the generator relay. The power flow is like this:

C
shore power------+-----+----+--------loads
generator---------+ |
Inverter-------------------------+

You have to decide what priority you want the sources to have. Mine
is

1) inverter
2) generator
3) shore power.

The logic is thus. If the shore power starts to go bad (storm,
brownout, etc), I want to be able to start the generator and have my
house load transferred to the generator automatically. When I stop my
generator I like to let it idle for a bit to cool. Therefore if I
turn my inverter on, I want it to assume the load and unload the
generator so that it can idle down. And I want to start the generator
and let it warm before accepting load from the inverter. The time
delay relay already has some built-in delay but perhaps on occasion I
want more. Very cold weather, for instance.

I understand. I'm not so concerned about automatic/seamless
switchovers in the case of power failures or brownouts though. For my
purposes, whether I'm on shore or battery power will be a function of
where I'm camped or a specific decision of mine. The generator would
only be used when shore power is not available and I need to run the
A/C. (Or maybe the toaster: see "Toast" thread from a few weeks ago.)
However, in situations like this I would be more likely to move or use
the evaporative cooler as I mentioned above.

My main question was regarding why the inverter can't feed the
existing ac wiring and outlets and I think I've deduced from your help
and that from Linus and Will is that this is not normally done to
protect the system from inadvertent use of heavy draw appliances,
(A/C, microwave, toaster), while running off the inverter.

I would be more than happy to close/open a switch to direct inverter
power to the coach instead of shore power. I think I can remember not
to use the heavy duty appliances when using the batteries.

One other minor bit of wiring change is to power the converter before
the inverter in the chain. Where the "C" is on that diagram. You
obviously don't want the converter powered up trying to charge the
battery using electricity from the battery that the inverter is using
to supply the house. Perpetual loop that doesn't work.

<sigh> would that it were. <g>

To summarize the steps involved:

1. Get a second changeover relay.
2. Figure out where to put it.
3. Wire it in
4. Wire in the inverter
5. rewire the converter to take power ahead of the inverter.
6. wire in a remote control switch for the inverter.

This is all very easy but it does take some knowledge of electrical
wiring.

I'm starting to see the charm of the Giddings approach...

Not to be argumentative but doesn't a coffee maker generate about as
many BTUs as boiling water for a drip coffee pot?

If you are asking if a stove-top unit liberates any more heat than an
electric maker, the answer is obvious if you hold your hand over the
stove-top unit while it's heating. :-)

Can't do that, the kettle is there sucking up the heat particles. ;-)

I prefer the vacuum pot and have both an antique electric one for
indoor use and a stove-top unit for use on the coleman stove outside.
I tried the stove-top unit a couple of times inside but in the summer
the added heat was unbearable.

Where I am and intend to be when I hit the road full-time, I intend on
avoiding climatic extremes. If it's too hot to make coffee, it just
too dam hot to stay.


Oh, and on the PD converter, here is the best place to get super deals
on the thing.  PD's outlet store

http://www.progressivedyn.com/hotdeals.html

I'm in Canada so US suppliers can be a problem. When I can get to the
rig I'll find out what flavour charging system it has and then I'll be
back to find out if it should be replaced or not. Since most of my
battery charging will be from the solar panels do I need a "smart"
converter?

Yes, absolutely. Your batteries are at the mercies of your converter
whenever 120 volts is present regardless of the battery's state of
charge. The solar cells could have them fully charged when you plug
in. A dumb charger would simply start boiling them immediately
instead of waiting until it was finished charging.

I'm assuming the panels are gentler on the batteries than
the generator would be.

Not necessarily. A dumb solar controller is as hard on the batteries
as an equivalent sized dumb line-operated charger. Only if your
panels are tiny (couple of amps or less) can you get away with a dumb
controller.

No they're regular, medium sized panels. When installed they were
rated to develop over 200 amps combined under ideal conditions.

Thanks again, John.

Gin
.

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