Inverter won't run Conv/Micro Unit

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The output of most inverters is what is called a "modified sine wave". Only
the top of the line expensive inverters have a "pure" sine wave output that
looks the same a what your generator puts out. My microwave will operate on
my inverter ( 1200 watt model ) but will not get hot enough to pop all of a
bag of popcorn. Only about half the bag will pop and this takes about 6 or 7
min. which by then has depleated the 2- 6 volt Trojan golf cart batteries
down to a low enough voltage that the microwave would be in danger of self
destructing. I don't think my inverter has a low voltage cutoff. I think
your microwave is the device that is not accepting the output of the
inverter as it may be a newer one with enough smart circuitry to save itself
from harm from crummy & low voltage inputs. Dave in Canton Ohio

Owlman

2005-04-05 07:19:52 UTC

We have a 2500 W inverter/charger. I had been told that there was a
possibility that our conv/microwave wouldn't work with our inverter,
but thankfully, that is not the case. It works fine, in spite of the
fact that ours is a modified sine wave model.

The only problem we have with our inverter is that at some camgrounds
(fortunately very few) that have GFI circuit breakers on the hookup,
our unit will continue to trip the circuit. This has been a real
nuisance, but has only happened twice or maybe 3 times, and we were
able to change campsites to a site without a GFI.

Post by s***@comcast.net
I have a Heart 2,000 Watts Inverter/charger. It will run a 1500 Watt
space heater and a 1000 Watt coffee maker at the same time but won't
run a 1200 Watt microwave. Why not? Is it something to do with the type
of electricity (wave?) I'm over my head here but I don't want to send
the Heart for repairs if it's okay.
I've cell balance charged the battery bank, checked and cleaned all DC
connections. The inverter powers a sub-panel and most of the motor home
circuits from there. The microwave runs fine on shore power and from
the 7.5 KW gen-set.
Thanks for any help. Stan

Frank

2005-04-05 07:21:21 UTC

Post by s***@comcast.net
I have a Heart 2,000 Watts Inverter/charger. It will run a 1500 Watt
space heater and a 1000 Watt coffee maker at the same time but won't
run a 1200 Watt microwave. Why not? Is it something to do with the
type of electricity (wave?) I'm over my head here but I don't want to
send the Heart for repairs if it's okay.
I've cell balance charged the battery bank, checked and cleaned all DC
connections. The inverter powers a sub-panel and most of the motor
home circuits from there. The microwave runs fine on shore power and
from the 7.5 KW gen-set.
Thanks for any help. Stan

This is an older article on the subject but I believe it is still relevent.
In a nutshell; Quasi-Sine waves AC.

http://www.amplepower.com/pwrnews/micro2/

--
Frank Howell
www.fphowell.com

stuckinthemud

2005-04-05 15:32:14 UTC

I'll take a stab in the dark, based on some limited information. I would
WAG that you have too small a battery bank, too long of a wirte run from
that bank to the inverter or too small a wire. I assumne your 2000 watt
invewrter is a 2000 continuous, not peak. This inverter shouold run the
microwave if it is hooked up properly. If it is in fact a 2000 peak, then
the inverter is too small for the microwave.

Space heaters and coffee pots are large loads for an inverter...anything
with a heating coil is a large load. The microwave is theoretically a
smaller load measured by wattage. But the startup on the microwave may be
higher than the wattage listed. It may draw 1200 watts while running but
may take 2400 watts to get started. (This is just a WAG...I do not know for
sure that the microwave requireds more watts to start).

I have a 2000/4000 watt inverter and it runs my 1200 watt microwave just
fine. But only when the batteries are at peak condition. In the middle of
a sunny day (with my solar panels charginmg the batteries) I can easily pop
a bag of popcorn. I have a seperate bank of batteries for the inverter.

Tell us...how long and what gauge are your supply lines from the battery to
the inverter? What kind and how many batteries are in the bank? Are these
same batteries used to power asnything else?

Nate

Alan Balmer

2005-04-05 16:05:49 UTC

A 1200 watt microwave needs a lot more than 1200 watts. Look for a tag
on the bottom or back which tells you what the real power draw is. It
could be as much as 2400 watts, not counting any surge capacity needed
for motor startup.

Post by s***@comcast.net
Is it something to do with the type
of electricity (wave?) I'm over my head here but I don't want to send
the Heart for repairs if it's okay.

If it can support a 2500 watt resistive load, I'd say there's nothing
wrong with the Heart.

Post by s***@comcast.net
I've cell balance charged the battery bank, checked and cleaned all DC
connections. The inverter powers a sub-panel and most of the motor home
circuits from there. The microwave runs fine on shore power and from
the 7.5 KW gen-set.
Thanks for any help. Stan

--
Al Balmer
Balmer Consulting
***@att.net

bill horne

2005-04-05 17:58:28 UTC

I have a 1.5 cu ft nuker with a turntable and a fan. Label says power
"consumption" is 1450 watts. And other than the fact that I've never
seen one higher than 15 amps, where did I get the idea that 120 V
household appliances are limited to that?

--
bill
Theory don't mean squat if it don't work.

Alan Balmer

2005-04-05 19:35:56 UTC

I have a 1.5 cu ft nuker with a turntable and a fan. Label says power
"consumption" is 1450 watts.

And what's the cooking power? Sounds like about 800 watts.

Post by bill horne
And other than the fact that I've never
seen one higher than 15 amps, where did I get the idea that 120 V
household appliances are limited to that?

Duuno. Our house is wired for 20A circuits.

We have a microwave built into our stove, on a 240 volt receptacle,
30A each leg.

The last study I saw found that microwave oven efficiency ranged from
49 to 57 percent. That's four years ago, so they may have improved
some. Or not.
http://hem.dis.anl.gov/eehem/01/010512.html

APS (Arizona Power) says 57.5%, without qualifying the number. They
may be quoting best case to encourage people to use them. If anyone'
interested, they quote efficiencies for other kinds of ovens, both
electric and gas.
http://www.aps.com/aps_services/business/waystosave/BusWaystoSave_23.html

--
Al Balmer
Balmer Consulting
***@att.net

bill horne

2005-04-06 00:34:54 UTC

I have a 1.5 cu ft nuker with a turntable and a fan. Label says power
"consumption" is 1450 watts.

And what's the cooking power? Sounds like about 800 watts.

I don't know. It doesn't say anywhere.

Post by bill horne
And other than the fact that I've never
seen one higher than 15 amps, where did I get the idea that 120 V
household appliances are limited to that?

Duuno. Our house is wired for 20A circuits.

I have dual 20A in my kitchen, too, but the question is not how some
may wire their house, but what the law or code says about max amp
draw allowed for 120 V household appliances. IOW, I don't think a
manufacturer can make a 120 V 30 A bathrooom heater for sale in Walmart.

--
bill
Theory don't mean squat if it don't work.

Alan Balmer

2005-04-06 16:09:02 UTC

Post by bill horne
I have a 1.5 cu ft nuker with a turntable and a fan. Label says power
"consumption" is 1450 watts.

And what's the cooking power? Sounds like about 800 watts.

I don't know. It doesn't say anywhere.

It was probably just on the advertising sticker when it was new.

Post by bill horne
And other than the fact that I've never
seen one higher than 15 amps, where did I get the idea that 120 V
household appliances are limited to that?

Duuno. Our house is wired for 20A circuits.

I have dual 20A in my kitchen, too, but the question is not how some
may wire their house, but what the law or code says about max amp
draw allowed for 120 V household appliances.

AFAIK, all it says is that if an appliance needs more than 15A, it
must have a plug which will only fit in a 20A receptacle. I could be
wrong, but I can't easily find a reference which says otherwise, and
I'd point out that the OP's original question was about a 1200 watt
cooking power microwave, which needs over 17A even at the highest
recorded efficiency for microwaves.

Post by bill horne
IOW, I don't think a
manufacturer can make a 120 V 30 A bathrooom heater for sale in Walmart.

Even if they put a 30A plug on it? <g>

--
Al Balmer
Balmer Consulting
***@att.net

RichA

2005-04-05 16:08:42 UTC