| [GMCnet] Microwaves and inverters for Rob M. [message #231135] |
Sun, 24 November 2013 21:34  |
glwgmc
Messages: 1014
Registered: June 2004
Karma: 10
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Senior Member |
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Hi rob,
In addition to this good info, look carefully at the inverter itself. They vary widely in quality, wave form, tolerance for overload, peak time, efficiency, etc., etc. most microwave units will not like the "modified sine wave" inverters. So called "full sine wave inverters" may well be so inefficient that your 2000 watt inverter actually is more like a 1200 to 1500 watt inverter on a good day. Look carefully also at the microwave itself. It may draw considerably more at startup than it does several seconds later. If the rated wattage on the microwave is more than about 60 to 70% of the rated continuous wattage of the pure sine wave inverter, and/or the inverter is more than two or three feet from those batteries, you will get the behavior you are observing.
Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed & hand crafted
in the 1907 former Masonic Temple building
in historic Kerby, OR
Http://jerrywork.com
"...................
Rob,
The questions are:
1 - How far is the inverter from the bank (of 2ea 6CGs) in feet of cable?
2 - What size cable?
3 - How new are the 2ea GCs?
4 - Have you checked the electrolyte density when you think that they are fully charged?
I have three (maybe 4) installations a lot like that and they have run effectively for years. (Except one time an owner called to ask why the microwave shut everything down. While we were on the phone - marine VHF actually - He figured out that he was running both the cabin A/C and the microwave off the house bank and inverter.)
What I suggest you do before you do anything else is -
Put a meter on the bank directly - On the posts, not even the cables or clamps.
If the voltage sags there, then get a refractometer or a temperature compensated hydrometer and see if the bank is really charged to full density of 1.260. If that is right, then maybe the batteries are over age. But, you should be able to support that load with what you have if everything is right.
Matt
--
Matt & Mary Colie
'73 Glacier 23 Chaumi?re (say show-me-air)
Now with 4 working Rear Brakes
SE Michigan - Twixt A2 and Detroit
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Jerry & Sharon Work
78 Royale
Kerby, OR
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| Re: [GMCnet] Microwaves and inverters for Rob M. [message #231999 is a reply to message #231135] |
Mon, 02 December 2013 16:58  |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Jerry,
Thanks for the observations, next time I'm at a rally or convention I'll get one of the electrical guru's to look at the setup and
help me figger out what's going on.
Regards,
Rob M.
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
From: Gerald Work
Hi rob,
In addition to this good info, look carefully at the inverter itself. They vary widely in quality, wave form, tolerance for
overload, peak time, efficiency, etc., etc. most microwave units will not like the "modified sine wave" inverters. So called "full
sine wave inverters" may well be so inefficient that your 2000 watt inverter actually is more like a 1200 to 1500 watt inverter on a
good day. Look carefully also at the microwave itself. It may draw considerably more at startup than it does several seconds
later. If the rated wattage on the microwave is more than about 60 to 70% of the rated continuous wattage of the pure sine wave
inverter, and/or the inverter is more than two or three feet from those batteries, you will get the behavior you are observing.
Jerry
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Microwaves and inverters for Rob M. [message #232080 is a reply to message #231135] |
Tue, 03 December 2013 09:20 |
habbyguy
Messages: 896
Registered: May 2012
Location: Mesa, AZ
Karma: 3
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Senior Member |
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My coach was about the worst case scenario for an inverter installation, with the inverter installed in the "equipment room" (under the tilt-up bed in the back) and the two house batteries in the opposite front corner. I did the math, and ran a combination of very flexible 1/0 copper cable and 2/0 copper cable, and my el cheapo 1000 watt (continuous) Harbor Freight inverter will handle a legitimate 7 amp AC load (which is essentially the full rated 1000 watt output). When I initially installed the inverter using only the #4 wire running back to the DC distribution block, it would handle only 100-200 watts of load before tripping the low voltage alarm.
I have what I believe to be the original microwave in my '78 Royale, and it runs just fine on the inverter.
Mark Hickey
Mesa, AZ
1978 Royale Center Kitchen
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