coffee maker vs inverter

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edjahar42

Member
Joined
Jul 3, 2011
Posts
12
Hello all, 1st post here.
I've had my '94 pace arrow class a for two years now and am going to try the inverter for first time on an upcoming trip up West coast.
It wouldn't carry any load so I made do with plug-in or generator. Just put in 4 new golfcart batteries, it will run tv and lite loads but the MrCoffee or microwave put it in shutdown mode. I checked wire and connections, all good. It is a 2001 Heart Interface 1800 HD that the previous owner had installed in Houston for $3700.00 including $1650.00 labor!
Should it run the coffeemaker or micro., nothing else was on at the same time.
All replies appreciated.
Ed
 
An 1800W inverter should be able to run a microwave or coffee maker, but not both at the same time.  Check the cables and connections at the battery and the inverter.  Look for any corrosion or loose connections.  Shutdown is usually due to low battery voltage and a bad connection or loose cable could let the inverter see enough voltage for light loads but not enough for a heavy load.
 
In addition to looking for corrosion also check the cable size. Under sized cable can lead to excess voltage drop even if the wire has the rated "amp capacity".

ken
 
Good point, Ken.  You would think that for over $5300 they would use the right cables :(
 
Some appliances can be damaged by inverters that put out a "modified sine wave" (basically a square wave) instead of a sine wave.  I have heard others complain that their coffee makers were damaged.  You might check to see if your inverter puts out "MSW" and if it does, keep an eye out for anything not working right upon first usage.
 
Thanks guys, I've checked the connections, removed, cleaned replaced, the wire is heavy welding lead type wire, only five to six feet long, and I tried the coffeemaker and micro one at a time with nothing else on.
I don't want to use the micro on the inverter, but I would like to use the Mr Coffee.
It is a MSW
 
Does the inverter give any reason code for the shutdown?  It may not be low voltage but something else.  An appliance that doesn't like the MSW wouldn't usually cause an inverter shutdown unless it was drawing more power than the inverter was capable of supplying.  A microwave oven or coffee maker should not do that.  Try a purely resistive load like an electric heater and see if that causes the shutdown.
 
A coffee maker is a resistive load - basically just a heater (plus the timer and on/off switch).  Try some lighter loads and see if you can determine how much power draw it takes to cause the shutdown.

Do you know which outlets are powered by the inverter? Are you sure there is nothing else on an inverter-supplied outlet that is drawing 120v power?

The inverter should have an error code or message that gives the reason for the shutdown - sometimes just a colored or blinking light. It is probably low voltage, but check the error status to be sure.

Be aware that the approximate 1000 watt draw of the coffee maker requires something like 90-95 DC amps from the batteries. That's a really major load and requires big cables between the battery and inverter as well as pristine connections.
 
Thanks Gary,
I'm beginning to wonder if my inverter is fully charging my batteries, but even at 12.6 volts as opposed to 14.4 they should run the coffee maker longer than ten seconds?
Ed
 
A coffee maker is a resistive load
Click to expand...

Of course it is, what was I thinking? :(

We need the shutdown code and that will tell us exactly what the problem is.
 
Ned said:
Of course it is, what was I thinking? :(

We need the shutdown code and that will tell us exactly what the problem is.
Click to expand...

But the fancier ones nowadays have electronics and timers in them...
 
AllegroRV [KodiakRV] said:
But the fancier ones nowadays have electronics and timers in them...
Click to expand...

Yes, they do, but I think the problem is related to the large loads.
 
edjahar42 said:
Thanks Gary,
I'm beginning to wonder if my inverter is fully charging my batteries, but even at 12.6 volts as opposed to 14.4 they should run the coffee maker longer than ten seconds?
Ed
Click to expand...

12.6 volts is fully charged. The SOC (state of charge ) charts vary some but 12.6 to 12.8 volts is considered fully charged after the surface charge has dissipated.
 
My coffeemaker is a plain on-off 1000 watt proctor-silex, still works fine on shore power.
My inverter was made in '01 it doesn't show codes.
thanks,
Ed
 
Just out of curiosity, what size inverter do you guys have and what do you run on it?
 
We have a 2000W MSW Heart Interface 20D and run just about anything but the air conditioners.  The microwave is ok for a couple of minutes and the coffee maker and toaster work fine, just one at a time, however.  We also run the DirecTV DVR, 3 computers, the satellite modem, wireless router, printer, scanner, and various chargers.  We do turn some things off when not in use to conserve the batteries.
 
Ned said:
Good point, Ken.  You would think that for over $5300 they would use the right cables :(
Click to expand...

I've seen "professional" installations with 2ga when it should have 2/0 if not 4/0. My coach came with a 2000 SW inverter. The cable run is 16 to 18 feet and Monaco used 4/0. I changed the inverter to a 2800 and added a second run of 4/0 cables. Monaco should have used MC350 or a double 4/0.


A aside on professional installations:
I remember getting a call from Jean Hart that his coach was tripping a GFCI outlet when he plugged into it. I drove out to his camp site to see what was causing the problem. What I found first was the his coach chassis was "hot", meaning the chassis had significant voltage. Turned out the Camping World had just "fixed" his inverter after the 12 volt cables had chaffed through and grounded out ( I think it also caused a small fire). They fixed the 12 volt ok, but reversed the 110 output. Since inverters internally DO connect the negative and the ground, that meant the chassis had become hot tripping the GFCI. This could have been serious if one was standing on wet ground when the touched the chassis.
 
I agree, Ken, professional doesn't always equate to good.  If the original Houston installer was PPL, I would have little faith in the quality and would check it carefully.  My exposure to their service department convinced me they know little about RV electrical systems.
 
...but even at 12.6 volts as opposed to 14.4 they should run the coffee maker longer than ten seconds?
Click to expand...
Yes it should, if the wire is adequate and the connections solid. But the 12.6v is suspicious, since the resting voltage after charging is normally 13.6v. While it is true that 12.6v is a full charge, that number is for a battery that has had the surface charge removed by a load.

How far is the inverter from the batteries and what size wire is used to connect it?
 
The cables are 5 to 6 feet in length, all connections are clean and tight, the cable is at least 1/2 inch thick!
The inverter as stated above was installed in July '01 and was used by the previous owner without complaint.
Looks like I might need a new inverter.
 
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