Testing running roof air via inverter

pianotuna wrote:
Hi Itinerant1,

When the Magnum is set to load support and there is, for example, a 15 amp shore power supply @ 120 volts, then when more than 15 amps are needed the excess current is taken from the battery bank. I.E. running a 10 amp coffee pot while running a 16 amp microwave. However the output voltage will still sag as the load increases.

On the other hand, if a "weak" 15 amp shore power supply @ 96 volts is being used to attempt to run an air conditioner, then an autoformer can "boost" the voltage up to 108. Without the autoformer the air conditioner would be damaged pretty darn quickly.

One of the few design faults of the Magnum is that the cooling fans shut off when the inverter or generator are turned off. I had been using load support help with the surge from the roof air, and fridge from my Yamaha generator. It was a hot day and so the load was 1900 watts from the AC and 325 watts from the fridge. I decided to go shopping--and so I turned off the load support and then turned off the generator. When I came back an hour later the red fault light on the Magnum remote was on. When I started the generator, no power would pass the Magnum. I bypassed the unit, and I had power again. That is when I noticed the soot marks on the wall above the Magnum.

Earlier in the summer of 2016, I was in a campground and it was hot as Hades. I did not yet own an autoformer. The voltage was only 102 on a 30 shore power feed at the campground. I found out, more or less by accident, that I could force the Magnum to do "voltage support" by dialing down the input amperage to just 11 amps. I do have a modest solar system and that meant I was able to run only the roof air from the (low voltage) shore power supply, without totally draining the battery bank. It did cause the Magnum to become pretty hot (I don't remember the numbers).

I do not recommend forcing the Magnum to do voltage support.

One other oddity is that sometimes the Magnum will not function if there is a ground fault shore power supply. Some it will work just fine with. If I bypass the Magnum the ground fault does not trip--so the issue is something inside the Magnum.

I think I understand what your saying above but as I read it some of it has me wondering why. I'm no rocket scientist here and the brain matter can be in the perpetual state of fog so bare with me on my questions.

The first paragraph makes sense the nature of batteries some will drop faster than others.

Second paragraph is where I start to drift I guess. I thinking of my experience with MSH3012M for the past year, now my system has not been turned off at all whether I was plugged in to shorepower or not. My understanding is that the inverter (load sharing) has built in saftey features and assuming you have the remote settings set properly that it will shut itself down or not let it work (load share) till certian parameters are met. I thought that one of the pluses of the hybrid was if there is "weak power" it can supplement it within the set parameters.

You say "One of the few design faults of the Magnum is that the cooling fans shut off when the inverter or generator are turned off." Unless I misunderstood about the ac/ fridge experience is once you turned off the ac/ fridge that is what you mean turning off the load support. Then when shutting down the generator you still left the inverter on gathering power from the sun to charge your batteries (I'm guessing that you had solar at the time). So unless the batteries where drained beyond the LBCO or you physically turned the inverter off the fans should stay running till the inveter cools off or it would of shut itself down before hand for over heating.

I've just went back into the manual a reread section 3 (operation) of load sharing and fault settings and it just seems there are features to prevent the inverter to operate with in the parameters (preset/ or manually changed) to operate with low voltage or "brown out" as stated in the manual.

The ground fault thing I have not come across since installing the system I've only been in maybe 6 state campgrounds that had power.