Neon John wrote in
:

(Nothing is funnier than a boater with a new 4KW inverter carrying his
electric heater down the dock with that knowing smile on his face....)

Yup. Old rule of thumb, a gallon of gas is about the energy
equivalent of about 1000 lbs of lead-acid batteries.

John


Thanks. Good rule of thumb.

http://www.fleetsubmarine.com/battery.html

On Thu, 24 Feb 2005 11:46:01 GMT, Larry W4CSC wrote:

How many amp-hours are aboard to run electric blankets and the other loads
all night?

======================================

It's not really a problem believe it or not. On our old boat the
house bank was 4 golf cart batts in series-parallel, total capacity of
440 A-H, usable capacity about 150 A-H. We had a 7.5 KW genset so
recharge was never a problem.

The electric blanket has a peak load of 300 watts translating to about
30 amps at 12 v. Duty cycle is about 50% on a chilly 50 degree night
in the north east. So for 8 hours of sleep we were pulling down about
120 A-H for the blanket (15 x 8), and maybe another 30 A-H for the
fridge. Never had a problem. The batts were 3+ years old when I sold
the boat and still going strong.

For the new boat (GB49 trawler), I plan a house bank made up of
individual 2 volt cells bolted together. It will weigh close to 1,000
lbs but that's not really an issue on a boat that weighs 60,000 fully
loaded. Total capacity will be over 1,000 A-H with usable capacity
greater than 350. Those 2 volt cells are guaranteed for 10 years so
they may turn out to be the last battery I ever buy. Recharge will be
via a high power inverter/charger, 20KW generator, and/or high
capacity alternators.

Might be a dumb question, but did you have anything else drawing off the
inverter the 20% of the time it didn't work? I'd say you are close to the
capacity with just the microwave.

Cheers

"Comcast" wrote in message
...
I just purchased a Tappan 550W microwave that consumes 850W. I
also purchased a Xantrex Xpower 1000W inverter (modified sine wave).
About 20% of the time, when I start the microwave, the light turns on,
the turn table starts to rotate, and just as the magnetron starts up,
the microwave shuts off. The microwave seems to have lost power since
the clock resets. The other 80% of the time, the microwave works fine.
Once it successfully starts up, it will run continuously without a
problem.

The inverter has a continuous rating of 1000W with a peek output of 2000W.
I can't imagine that the microwave ever uses this much power to start.
The fault light on the inverter does NOT come on.

I have 2 large deep cycle batteries connected in parallel. They are
in excellent condition and provide over 260AH. I have connected the
inverter directly to the batteries with 2 AWG battery wire that I
purchased at the auto store. Is there a problem with the microwave
or inverter? Should I buy a more powerful inverter?

Thanks
Brent

Wayne.B wrote in
:

For the new boat (GB49 trawler), I plan a house bank made up of
individual 2 volt cells bolted together. It will weigh close to 1,000
lbs but that's not really an issue on a boat that weighs 60,000 fully
loaded. Total capacity will be over 1,000 A-H with usable capacity
greater than 350. Those 2 volt cells are guaranteed for 10 years so
they may turn out to be the last battery I ever buy. Recharge will be
via a high power inverter/charger, 20KW generator, and/or high
capacity alternators.



I like this guy!.....(c;

I've mentioned it before, but have you seen these guys in Colorado that
make all their own power?
http://www.otherpower.com/

Talk about energy independents!

Neon John wrote:

Depending on the length of the run, that #2 wire may be a
bit small.

According to the chart in the West Marine catalog, it has a resistance
of 0.157 ohms per 1000'. At roughly 100 amps draw (1000 watts or so
output) that means about a tenth of a volt drop for every three feet
of cable run (two conductors) between inverter and battery. Under
peak current that would get larger. Depending on the length of the
run, it could have a significant effect.

To find out, check your battery voltage at the inverter terminals
while turning on the microwave. This will also check the resistance
of the connections. If you made the cables up using untinned auto
cable rather than tinned marine cable, it might be more prone to
corrosion and resistance in the lugs.

If the voltage at the inverter is OK, then it's probably the
difference between modified and pure sine wave.

Does that model microwave lower its power levels by running less than
100% duty cycle, so if you're running at less than full power you keep
hearing it cycle on and off? I ask because this chart
http://www.sailorsams.com/mall/tm5030_power_levels.asp seems to imply
that it actually lowers the peak power consumption. If so, try
running at 90% power. (It could also be that the chart shows average
rather than instantaneous consumption, or that the guy who made it was
using assumptions rather than knowledge.)

- Walt Bilofsky

"Comcast" wrote:

I just purchased a Tappan 550W microwave that consumes 850W. I
also purchased a Xantrex Xpower 1000W inverter (modified sine wave).
About 20% of the time, when I start the microwave, the light turns on,
the turn table starts to rotate, and just as the magnetron starts up,
the microwave shuts off.snip

I asked SailorSams.com (from which I am buying this model) about this.
He had no definitive answer but did say "The distributor is going to
send the Tappan microwaves to Xantrex, to let Xantrex specify which
of their inverters should be used with which Tappan microwave." If
you are not in a rush, you might want to ask them in a month or two.

- Walt Bilofsky