What fuse is blowing??
Are you taking about the 'reverse polarity' fuse(s)?
You have a bad battery or cables are reversed.
And if lights are dimming after the fuse blows your converter is also bad.
Converter output should be 13.6V DC (provided you have 110V AC input)
Need to check battery voltage with converter off (or cables disconnected)
Get out a volt meter and use it.
Here is a troubleshooting guide (for Parallax Converters BUT is good for converter troubleshooting)......
LINK
Is it time for your medication or mine?
2007 DODGE 3500 QC SRW 5.9L CTD In-Bed 'quiet gen'
2007 HitchHiker II 32.5 UKTG 2000W Xantex Inverter
US NAVY------USS Decatur DDG31