Donco234

Roger that

Doesn't matter how many batterires you have, if you take more out than you replace, you will run out.

I have examined the output of several types of inverters on an oscilloscope. None make a pure sine wave. What confuses most electronic devices is the bounce in voltage and frequency when large loads are switched on and off. The circuitry that mimics the sign wave inside the inverter do not do so as well at all load levels and battery input voltages. Some are better than others. All personal computers have power supplies and filtering that makes them mostly imune from power wave form geometry.. Still don't reccomend replacing an expensive inverter just to get one that "claims" better sine wave simulation.

I note that you are in the Pacific Northwest, as I am. All solar panels will produce a less than their rated output the farther north you are AND we (in the Northwest) have had a lot of cloudy conditions lately. If hypothetically both your cells are putting out 75 watts during bright times, and nothing at night, and very little during cloudy times, it would be very easy to use more than the cells can replace. Most likely, as others have noted, your batteries are never reaching full charge unless you run your engine for quite a while. The nature of battery charging is that the first part of the charge goes in fairly quickly and then the charge rate tapers off quite a bit before full charge is reached. When you crank up your RV engine, it will charge low batteries at high rates at first but taper off at about 85% to a much slower rate. I suspect that you may be stopping this charge somewhere in this range. As others have said, you really need to be able to estimate your daily electrical use before you can know just how large of solar panels you need. I have 450 watts and they do a good job of "prolonging" the time before I need to recharge with shore, engine, or generator power. You may find that a good/quiet portable generator with a smart charger would do a better job for a lot less money.

WHY, As an Electrical Engineer I can tell you that the words "Pure Sine Wave" or "Modified Sine Wave" as it applies to RV inverters has more to do with marketing than electricity. NO RV INVERTER has a Pure Sine wave output, they simply use circuity to imitate a pure sign wave and only partially do so. As I told my good friend recently who had recently replaced his propane fridge with a residential, "you would be wasting money". I can't think of a reason to remove a perfectly good inverter and replace it with a modified sine wave of the same size. No appliance or gadget that I know if that is commonly used in an RV would even know the difference.

My motorhome will "mimic" this problem with the battery cut off - cut off. There are a couple of small "keep alive circuits" for radio memories etc. that bypass the cut off. These circuits can bleed a little power onto the normal circuits which is enough to illuminate low current devices momentarily. Also some solar battery maintenance panels (the small ones) can cause this. It sounds like to me that your main disconnect is not making connection. My coach has both a "salesman type switch" disconnect AND a manual disconnect switch near the batteries. I would start there

Thank You, this helped the DW so much with her cooking.

We are full timers. My wife slowly has added more and more electrical appliances so, soon we had to "manage" how many loads were on each circuit. We purchased some small colored round adhesive backed little markers from the local office supply. After identifying which circuits were powered by each breaker, we put a colored circle on each circuit and it's breaker. We only identified the circuits that were on our inverter which was fed through a single 30 AMP breaker. Loads not on the inverter seemed not to be of any issue. My DW seems to now understand the circuitry and what can be run simultaneously.