Hi,
We need more details on the existing converter. It may well be better than the stand alone charger that you are considering.
How many amp-hours is the battery bank?
I agree with other posters, for the list of items you wish to power a 300 watt pure sine wave would be a better choice.
If you do stick with MSW then the AC monitoring may not work correctly. I chose a watt meter. If you plan on staying below 1800 watts then a Kill-a-Watt meter is a "best buy".
I found some hall effect ammeters for my DC but they are hard to acquire.
