Don't just buy an inverter using round numbers....add up the wattage of what you want to power, and buy one that will do the job. Remember that the bigger the inverter, the more you can run, and the faster it will suck your batteries dry.
I got a 150w pure sine inverter and installed it with this
15a auto transfer switch.
Here's the
post on my inverter install.
I've since upgraded the converter/charger to a Progressive Dynamics with charge wizard, so I can restore the batteries with only a brief runtime when we are boondocking.
It's also a good idea to install a voltage meter if you don'y have one...I use it along with this chart to monitor battery charge:
