From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Conventional cheapo small AC fridge in an RV?
Date: Thu, 29 Jul 2004 13:57:34 -0400
Message-ID: <t0eig05n9mn8ud6lt7gcasvf29ipffcccb@4ax.com>

On Thu, 29 Jul 2004 15:00:50 GMT, jac <jungle@io.com> wrote:

>Thanks to this groups responses, I've done this. within the last week, my 3 way
>fridge started smelling of ammonia and so I went shopping. After seeing $1000
>Plus prices, I went to Home Depot and found a very nice, two door fridge,
>brushed stainless doors for $179. I already have a stand alone ice maker that I
>have been running when the generator is on or plugged into shore power. I like
>to boon dock so shore power is not usually available. Well, I bought a Coleman
>1000 watt (PMP1000) inverter for about $80, and hooked it up two days ago, with
>no generator or shore power, to see how it would perform. So far, 48 hours into
>the test, both the fridge and the ice maker are doing fine as of this morning.
>I'm "home testing" it to see how long it'll run without generator assistance.
>The inverter shuts down at 10.5 volts, so I'm assured on not having a dead
>battery.. (that part remains to be proven <G>). I took Neon Johns advice and
>installed two 6 volt golf cart batteries a while back for power.
>So, my point to this is: if you're considering this as an option, so far, I've
>very pleased, and saved over $1000 (new fridge, shipping, installation) via this
>replacement.
>jac

Hi Jac.  Bet you get that a lot :-)

Actually I recommend against golf cart batteries but if they work for you
that's good.

I've run into a problem running my AC fridge with an inverter that I did not
anticipate.  The problem is the inverter tripping on OVERvoltage while
charging the batteries.  The inverter should not trip until at least 15 volts
but the several different ones I've tried all tripped at or below that value.
My vector charger peaks at 14.75 to 14.8 volts.  In cold weather my alternator
will occasionally hit 15 volts for a minute or two.  The result is the
inverter tripping and the result of that 2 times now has been a fridge at 90
deg when found.

Inverters are so cheap now that I consider them expendable.  Therefore my
solution was to find the voltage sense resistors on the inverter PCB and
disable the trip by wiring the sense input to regulated voltage on the board.
This defeats the low voltage trip too, but that's not a problem since I use
the E-meter's undervoltage trip to disconnect the pack.

I've tested 5 or 6 different brands of 1000 watt class inverters and all show
this problem to one extent or the other.  There are so many designs that a
generic solution isn't possible to describe.  I've had the voltage sense
disabled in my xantrex inverter for a couple of months now.  We'll see how it
works.  If there are no major problems, I'll just leave it that way.  If there
are, I'll devise a better solution, probably an add-on board that does smart
sensing.

BTW, you really ought to spend the money on an E-meter now that you're using
your pack so much.  It makes battery management a dream.

John