We spent 2 wonderful weeks in Virginia recently.
Had a great time in that great state!
Our 1st week we stayed at Loft Mtn camp ground in
Shenandoah National Park. Since they have no hookups
we were on battery power for 8 days.
We have 2 group 24- 12v batteries in parallel.
We were pretty frugal with lights but did not do without.
I pulled one bulb out of the light over the sink and also
the one in the bathroom. We have an energy saving
fluorescent light over the table. We used lights only
when absolutely necessary.
We also have an LCD TV that we watch occasionally
using a little cigarette socket inverter.
Obviously the fridge was on gas mode.
Can only guess that we watched 4 hours of TV in the
1st 4 days.
We arrived Sunday afternoon and set up.
We ran the batteries pretty flat by Thursday afternoon.
I have a little cheapie generator that's supposedly rated
at 1000 watts. It claims to have 1200 watt surge with
1Kw continuous but I'm pretty sure it kicks it's breaker
at much over 800 watts continuous.
Anyway on Thursday afternoon during "generator hours"
I connected a charger to my batteries and fired up the
genny. I have a little portable 2/10/25 amp charger
that I use to charge with.
Now you are wondering why I don't just plug in the
I have discovered that my onboard power center does
a fine job of charging and maintaining my batteries but
it's a bit too gentle on the batteries. In other words it
does charge them fully but it does it slowly. When I start
that generator I want it do get the job done as fast as
possible. The genny is 2 cycle with a fairly large muffler
but it ain't no Honda. It's not nearly as loud as a weed
whacker but it's noisy enough.
My portable charger running in 25 amp mode is working
the genny harder and charging the batteries faster than
the onboard power center does.
As I said, I ran the genny for 1 hour on Thursday.
We were running low on charge by Saturday afternoon so
I ran the genny again. This time because I was still
trying to figure out the fastest way to get a charge,
I did plug in the trailer rather than using my portable
I noticed immediately that the genny was working harder.
I could tell by the exhaust sound and a very slight smoke
from the exhaust that it was laboring.
I thougt "GREAT" my batteries are really getting a
I ran the genny about 90 minutes.
We attempted to watch TV at bedtime that night and
found that the inverter was kicking out and my battery
indicator was showing zero!!
Yikes!! Wanting some entertainment as well as
needing the fridge to continue to operate I plugged
my truck back in for the night so we could "borrow" some
juice from it's battery. We were leaving the
next morning and would have AC power at our next stop.
Once I got home I attempted to discover why my
battery charging attempts seemed to go down hill
as the week progressed.
After this long story here is what I discovered--
My dometic refer has a little tiny rocker switch above
the freezer door. This is labeled "environment" or something.
It is a heater that warms the area between the freezer
and fresh food doors. That little strip you can see below
the freezer door can sweat in humid conditions so they
put in a heater to warm it up!!
YIKES-- It uses a considerable amount of juice when
it's on. My freezer door is so close to this switch that
it can actually bump the switch to the ON position.
Also we had the fridge in "auto" mode. So as long
as I was charging the batteries with my portable
charger or on battery power the fridge was in gas mode.
BUT when I plugged the trailer into the genny on Saturday
the fridge automatically switched back to AC mode and
it was sucking up nearly half of my genny power as
I was trying to charge batteries.
Lesson here-- If you are on battery power be sure
and check that little "environment" switch above the
freezer door AND be sure the fridge is on manual GAS
mode if you plug into a genny to charge batteries.
Otherwise the fridge can really suck you dry while
At home I got out my industrial clamp on ammeter and
did some more experimenting.
I found that I can boost my charge rate by nearly 10 amps
if I plug BOTH my trailer and my portable charger
into my little 1Kw genny. The portable charger drops
from 25 amps down to about 18 but the onboard trailer
power center adds it's juice at the same time
My genny is putting out an extra amp of power with
both running at the same time verses just the charger.
This is 1 amp at 120 volts. That translates to nearly
10 extra amps at 12 volts so I am getting 10 more
amp hours per hour when I charge with both units
at the same time.
That's enough extra charge per hour to watch a movie on the TV if we want to
Sorry for the long winded story but maybe what I learned
can help someone else out there!