lvnrdream, if your existing converter already has a good 3-stage charger, there is no need to add an inverter that also has a charger. You can add something like a Xantrex 1000 watt PROwatt inverter
. The PROwatt does not have an internal transfer switch to automatically switch from shore power to the inverter in the event of 120V power loss, but an external transfer switch
is available for around $60.
Magnum makes a similar setup (1000 watt PSW inverter w/o charger and external transfer switch). We have one in our 5th wheel, but I don't see it listed on their website.