Hi Neil and others...thanks! So, along with the facts you've come up with I have a couple of screw ups of my own to add in the mix. And that shop vac you pictured is the exact one. Pics attached;
...battery (2 like you see in this pic) and
...wire to converter....
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My wire is not heavy enough
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the wire is approximately 3 feet long....pics attached.
I only use it to suck up cookie crumbs and inflate the dinghy. That little shop vac will inflate and deflate a dinghy quick. I usually have to break it out after a weekend on the boat.
Computer charging, phone charging, computer operation, dvd player operation and Sirius Satellite radio all plug in and do fine.