the 12 volt outlet

Couldn't the Solar Battery Tender be connected to the battery in the back, with the solar panel in the back window?

 

I have a solar battery tender that plugs into the OBDII port for charging.

 

This would work, but conductors would have to hinge with the hatch ...

 

This works! I assume that the OBDII circuity has some kind of current limiting feature in case the collector or its conductors short. I would be happier with a fused circuit.

 

Here it is. VW uses them when they ship and store the cars so the battery doesn't die.
12V VW SOLAR PANEL BATTERY MAINTAINER WITH OBD PLUG IC0915687D | eBay

 

I have a question that is not exactly on the subject but I do not like to start new threads unnecessarily. I collect water from a spring in the hills of a neighboring county. My four containers total about 28 gallons. I bought a small 12v water pump that has spring clips designed to power the pump from a car battery. Would I risk any harm to my Prius if I left it on and use its battery to power the pump?

 

There's lots of people powering appliances in their homes using power inverters attached to their Prii, so I can't see a problem.

 

Thank you for responding El Dobro. I think I remember a post where someone used one of the outlets inside the car to power a hand vacuum and fried some expensive component, which makes me more than a little nervous about powering a $75 pump from my $25K car. I would be interested in knowing why it happened and if there is a hazard, is it mentioned in the manual?

 

There is a 15A fuse dedicated just for the central power outlet. It is not connected with any other system. Don't worry, just press Start button to Ready state to omit discharge of 12V accessory battery.